Bicycle power meter

BACKGROUND OF THE INVENTION

0001A bicycle rider may desire information regarding the amount of power being input, output, or removed from the drive train of a bicycle during use. Power meters may be configured to detect and/or measure this power, and/or output or otherwise provide this amount of power. Bicycle power meters may use deformation or strain measurement devices, such as strain gauges, to measure deflection and/or deformation of a bicycle component during use to establish the amount of power. Traditionally the installation, positioning, and/or placement of these strain measurement devices is a difficult and tedious task as each strain measurement device would be individually positioned, placed, and/or coupled to the bicycle component, for example manually with a set of forceps or tweezers. After attaching to the component, the strain measurement devices were then communicatively coupled in some way to processing circuits installed separately and/or subsequently to the strain measurement devices. This traditional type of strain measurement device and separate circuitry construction and assembly requires a significant amount of effort, and is very costly.

0002<patcit id="pcit0001" dnum="WO2011074947A1"><text>WO 2011/074947 A1</text></patcit> discloses a measuring device for measuring torque between two annular members of a chain wheel assembly. The measuring device comprises an inner ring member and an intermediate ring member, which are respectively attached to the two annular members through attachment members. Multiple inner coupling members are provided for coupling the intermediate ring member and the inner ring member to each other. A strain gauge is mounted on an inner coupling member to measure its deformation. The measuring device is manufactured as a printed circuit board (PCB).

0003<patcit id="pcit0002" dnum="US20090119032A1"><text>US 2009/0119032 A1</text></patcit> discloses an input torque measuring device comprising a shear strain gauge attached to a spider arm or a crank arm and directly connected to a flexible circuit board.

0004<patcit id="pcit0003" dnum="WO2016030768A2"><text>WO 2016/030768 A2</text></patcit> discloses a power meter attached to a mechanical arm including at least one strain gauge and electronics for receiving a signal from the strain gauge and for determining one or more of force, torque, power and velocity from the signal, and a wireless transmitter for transmitting one or more of force, torque, power and velocity to a receiving device.

SUMMARY

0005In an embodiment, a power meter for a bicycle includes a body comprising a torque input section and a torque output section, the body configured to transmit power between the torque input section and the torque output section. The power meter also includes a printed circuit board ("PCB"). The PCB includes a substrate, at least one strain measurement device attached to the substrate, the at least one strain measurement device configured to provide a signal indicative of strain detected in the body, and circuitry, embedded in the substrate, the circuitry configured for interpreting the signal and determining a corresponding power transmitted between the torque input and the torque output section. The body includes a cavity configured for installation of the PCB. The substrate is of annular construction and disposed in the body around the torque input section.

0006The power meter according to the invention may further provide that the at least one strain measurement device is attached to the substrate such that the at least one strain measurement device is fixed in a plane of the PCB relative to at least one feature of the PCB.

0007The power meter according to the invention may further provide that the feature is formed in the substrate.

0008The power meter according to the invention may further provide that the at least one strain measurement device is a foil or wire type electrical strain gauge.

0009The power meter according to the invention may further provide that the torque output section comprises teeth.

0010The power meter according to the invention may further provide that the torque output section comprises chainring attachment features.

0011The power meter according to the invention may further provide that the at least one strain measurement device comprises planar electrical contact surfaces, and the PCB is configured such that the strain measurement device planar electrical contact surfaces are disposed facing electrical circuitry contacts of the PCB, the electrical circuitry contacts of the PCB communicatively coupled to both the strain measurement device planar electrical contact surfaces and the circuitry of the PCB.

0012The power meter according to the invention may further provide that the at least one strain measurement device is communicatively coupled to the circuitry of the PCB with a volume of an electrically conductive bonding material.

0013The power meter according to the invention may further provide that the electrically conductive bonding material is a fusible metal alloy.

0014The power meter according to the invention may further provide that the volume of electrically conductive bonding material comprises at least one distinct volume of electrically conductive bonding material, and both the PCB and the at least one strain measurement device are in physical contact with the distinct volume of electrically conductive bonding material.

0015The power meter according to the invention may further provide that the at least one strain measurement device is attached to the body with an adhesive.

0016The power meter according to the invention may further provide that the at least one strain measurement device attachment to the PCB comprises a structural support material.

0017The power meter according to the invention may further provide that the structural support material is disposed both on an edge of the substrate and on a surface of the at least one strain measurement device.

0018The power meter according to the invention may further provide that the edge and the surface are oriented substantially orthogonal to each other.

0019The power meter according to the invention may further provide that the at least one strain measurement device comprises a plurality of strain measurement devices disposed about the torque input section.

0020The power meter according to the invention may further provide that the plurality of strain measurement devices are disposed so as to align with strain measurement features of the body.

0021The power meter according to the invention may further provide that the substrate includes at least one strain measurement device attachment feature, and the at least one strain measurement device is disposed on the substrate so as to be aligned with the at least one strain measurement device attachment feature.

0022The power meter according to the invention may further provide that the strain measurement device attachment feature comprises at least one vacancy formed in the substrate.

0023The power meter according to the invention may further provide that the vacancies are configured to provide access to the at least one strain measurement device in an axial direction of the PCB.

0024The power meter according to the invention may further provide that the body further comprises bolt holes in the torque output section configured for attachment to a chainring, and the strain measurement device attachment features are disposed so as to correlate to the bolt holes.

0025The power meter according to the invention may further provide that the power meter comprises a same number of strain measurement features and bolt holes.

0026The power meter according to the invention may further provide that the circuitry is further configured to wirelessly transmit a second signal indicative of the determined power.

0027The power meter according to the invention may further provide that the body further comprises heat dissipation features.

0028The power meter according to the invention may further provide that the torque output section is configured for attachment to an annular rotor structure having at least one friction surface configured for generating friction to dissipate power provided at the torque input section of the body.

BRIEF DESCRIPTION OF THE DRAWINGS

0029<ul id="ul0001" list-style="none" compact="compact"><li><figref idref="f0001 f0002 f0003">Figures 1A - 1C</figref> are side views of bicycles, which may be used to employ one or more power meters;</li><li><figref idref="f0004 f0005 f0006">Figures 2-4</figref> illustrate an embodiment having a power meter integrated with components of a bicycle drivetrain, such as the drivetrain for the bicycle of <figref idref="f0001">Figures 1A</figref> or <figref idref="f0002">1B</figref>;</li><li><figref idref="f0007">Figure 5</figref> is an exploded view of the power meter integrated with a chainring carrier of <figref idref="f0004 f0005 f0006">Figures 2-4</figref>;</li><li><figref idref="f0008">Figure 6</figref> is a perspective view of the chainring carrier of <figref idref="f0004 f0005 f0006">Figures 2-4</figref>;</li><li><figref idref="f0009 f0010 f0011">Figures 7-9</figref> illustrate various views of the chainring carrier of <figref idref="f0008">Figure 6</figref>, with a cover removed;</li><li><figref idref="f0012 f0013 f0014">Figures 10-12</figref> illustrate various views of a printed circuit board ("PCB") of the power meter of <figref idref="f0009 f0010 f0011">Figures 7-9</figref>;</li><li><figref idref="f0015">Figure 13</figref> illustrates an exploded view of a power meter integrated with a chainring;</li><li><figref idref="f0016 f0017">Figures 14A-14B</figref> illustrate various views of the power meter integrated with the chainring of <figref idref="f0015">Figure 13</figref>;</li><li><figref idref="f0018">Figure 15</figref> illustrates a perspective view of the power meter integrated with multiple drive sprockets;</li><li><figref idref="f0019">Figure 16A</figref> shows an expanded view of the cross section indicated in <figref idref="f0010">Figure 8</figref>;</li><li><figref idref="f0020">Figure 16B</figref> shows an expanded view of the area indicated in <figref idref="f0019">Figure 16A</figref>;</li><li><figref idref="f0021">Figure 17</figref> is a block diagram of an embodiment of a power meter system;</li><li><figref idref="f0022 f0023 f0024">Figures 18-20</figref> show various views of the power meter integrated with a brake rotor; and</li><li><figref idref="f0025">Figures 21</figref> and <figref idref="f0026">22</figref> show exploded views of the power meter integrated with the brake rotor of <figref idref="f0022 f0023 f0024">Figures 18-20</figref>.</li></ul>

0030Other aspects and advantages of the embodiments disclosed herein will become apparent upon consideration of the following detailed description, wherein similar or identical structures have similar or identical reference numerals.

DETAILED DESCRIPTION

0031Strain measurement devices may be physically integrated with the operational circuitry of a bicycle power meter. Physically integrating strain measurement devices and operational circuitry structure may cause the construction and/or precise positioning of power meter components to be accomplished in a less expensive and/or less resource intensive manner. The strain measurement devices may be attached directly to a physical structure containing the power meter operational circuitry, such as a printed circuit board ("PCB") substrate, thus coupling the strain measurement devices and the power meter circuitry into a singular power meter PCB assembly. Further, fixably attaching the strain measurement devices to the PCB such that the position of the strain measurement devices in a plane of the PCB substrate is fixed relative to other components of the PCB assembly may allow for easier alignment and/or positioning of the strain measurement devices. For example, the alignment of the strain measurement devices may be established based on alignment of features of the PCB, which may be features of the PCB substrate and/or other PCB components.

0032Power meters may be used with different bicycle components to determine power transmissions through the component. In an embodiment, the power meter may be used in combination with the drive train of a bicycle. For example, the power meter may be integrated with a chainring and/or a chainring carrier for measuring power transmitted from through the crank arms and/or shaft through the chainring drive assembly and to the chain or belt of the drivetrain. The power meter may also be integrated with other elements of the drivetrain, such as a rear cog or cassette operatively coupled with the rear wheel, a crank arm or pedal, and/or a rear wheel hub.

0033Power meters may also be coupled with other components, such as one or more brake rotors of a bicycle with a disc-braking system. The power meter may be configured so as to dispose strain measurement devices radially between a wheel hub attachment section and one or more friction surfaces of a rotor and/or rotor assembly. Strain measurement devices disposed in this manner can measure the strain of the rotor and/or rotor assembly caused by the dissipation of motive forces between rotational forces of the road acting on the front and/or rear wheel of the bicycle and the friction surfaces of the rotor and/or rotor assembly where the motive forces are dissipated into other forms of energy, such as heat energy. This is believed to provide a measure of braking power or power dissipation of the braking system. In an embodiment, the power meter may be integrated with a carrier of the rotor and/or rotor assembly. As such, one or more strain measurement devices may be disposed on the carrier radially between a torque input section and a torque output section of the rotor carrier. For example, the one or more strain measurement devices may be disposed on the rotor carrier between a radially inner wheel hub connection section and a radially outer attachment section to an annular rotor member, the annular rotor member containing the friction or power dissipation surfaces.

0034In an embodiment, the power meter may be configured for use in an application wherein the transmission of power across a component involves a dissipation of energy as heat energy, such as a brake rotor application. To accommodate the additional heat energy, and/or the dissipation thereof, the power meter may include heat dissipation features, such as ribs, fins, or other features. For example, a rotor assembly may include a carrier, and the carrier may include the heat dissipation features. The heat dissipation features may be disposed and/or formed on a surface of the carrier, facilitating the transfer of the heat energy into an ambient environment, such as the surrounding air. These features dissipate the heat energy to maintain and/or limit a temperature of the rotor assembly to protect a PCB assembly of the power meter.

0035A bicycle may use multiple power meters. In an embodiment, a bicycle includes at least one power meter configured to measure the power input to the drive train of the bicycle, and at least one power meter configured to measure the power dissipated by the braking system. For example, a first power meter may be integrated with at least one chainring of the drivetrain, as is described herein, and a second and third power meter may be integrated with a front rotor and a rear rotor of the bicycle braking system, respectively. The values from these three power meters may be used to compare the amount of power input to the bicycle, and the amount of power dissipated by the braking system. The difference between these values may be attributed to rolling resistance of the bicycle, air resistance due to ambient air surrounding the bicycle during use, or other factors. In an embodiment, the three power meters are configured to transmit the measure power values to one or more component of the bicycle, such as a cycle computer, or other portable computing device or computer. For example, the three power meters may be configured to transmit the values representing the measured power to a same bicycle component, mobile computing device, or computer.

0036<figref idref="f0001 f0002 f0003">Figures 1A - 1C</figref> generally illustrate bicycles 100 with which a power meter may be used. The bicycle 100 includes a frame 38, front and rear wheels 79, 78 rotatably attached to the frame 38, and a drivetrain 70. A front brake 92 is provided for braking the front wheel 79 and a rear brake 91 is provided for braking the rear wheel 78. The front and/or forward orientation of the bicycle 100 is indicated by the direction of arrow "A." As such, a forward direction of movement for the bicycle is indicated by the direction of arrow A.

0037The illustrated bicycle 100 may be a road bike having drop-style handlebars 22, a mountain bike, or any other type of bicycle. The present invention has applications to bicycles of any type, including fully or partially suspensioned mountain bikes and others, as well as bicycles with mechanically controlled (e.g. cable, hydraulic, pneumatic) and nonmechanical controlled (e.g. wired, wireless) drive systems.

0038The bicycle 100 may include one or more shift units 26, mounted to the handlebars 22. A front gear changer or front gear shift mechanism 30, such as a front derailleur, may be positioned on the frame 38, such as on the seat tube 32, adjacent the front sprocket assembly 34 so as to effect gear changes to the front sprockets or an associated structure. A rear gear changer or rear gear shift mechanism 36, such as a rear derailleur, is mounted to a member of the frame 38 of the bicycle, such as a mount, rear dropout, and/or an associated structure, in a position to effect gear changes in a rear sprocket assembly 41. In some embodiments, the bicycle may only include a front or only a rear gear changer.

0039The drivetrain 70 comprises a chain 72, the front sprocket assembly 34, which is coaxially mounted with a crank assembly 74, and the front gear change mechanism 30, such as a derailleur. The drivetrain also includes the rear sprocket assembly 41 coaxially mounted with the rear wheel 78, and the rear gear change mechanism 36, such as a rear derailleur.

0040The crank assembly 74 includes pedals 76, two crank arms 75, and a crank spindle (not shown) connecting the two crank arms 75. The crank assembly may also include other components. For example, the crank assembly 74 may also include a chainring carrier or spider 77 configured to transfer torque between one or more of the crank arms 75 and the front sprocket assembly 34. In another embodiment, the crank arms 75 and the front sprocket assembly 34 may be torque transmittingly coupled in other ways, such as by being directly attached to the crank spindle.

0041The drivetrain 70 may also include a power meter 200. The power meter 200 may be configured to be coupled with, or a part of, the crank assembly 74. The power meter 200 may be integrated with a body, such as the chainring carrier 77 or rotor carrier 577, and may include one or more strain measurement devices 260, such as strain gauges, arranged in a generally annular pattern about the body. The strain measurement devices 260 are connected to circuitry and/or other sensors to generate power information, which may be transmitted to another bicycle component or external device for further processing and/or display. Alternatively, the power meter 200 may be coupled with the chainring assembly 34 directly, for example without the use of a chainring carrier 77.

0042The power meter 200 may also, or alternatively, be included with other components of the bicycle. In an embodiment, such as that shown in <figref idref="f0002">Figures 1B</figref> and <figref idref="f0003">1C</figref>, the power meter 200 may be integrated with a braking system to measure and/or otherwise detect braking power. For example, the power meter 200 may be integrated with one or more rotors 500 of a disc-braking system. As illustrated in <figref idref="f0002">Figures 1B</figref> and <figref idref="f0003">1C</figref>, a disc-braking system may be a system having a caliper 94 configured to apply a braking force to the rotor 500. Including a power meter with a brake rotor 500 may allow a user to determine the power dissipated by the braking system. Including a power meter with the brake rotor 500 may also, or alternatively, provide an indication of the braking forces applied to the rotor 500.

0043As is illustrated in <figref idref="f0002">Figure 1B</figref>, a bicycle 100 may include one or more power meters. For example, the bicycle may have a power meter configured to measure power input to the drive train 70 and the bicycle may have one or more power meters configured to measure brake forces and/or power dissipation. For example, the bicycle 100 may include a power meter 200 integrated with brake rotors 500 configured in the braking systems of the front wheel 79 and the rear wheel 78.

0044As is also illustrated in <figref idref="f0003">Figure 1C</figref>, a bicycle 100. In the illustrated embodiment, the bicycle 100 is a mountain bicycle with suspension components and/or flat handlebars. The bicycle 100 may include one or more power meters. For example, the bicycle may have a power meter configured to measure power input to the drive train 70 and the bicycle may have one or more power meters configured to measure brake forces and/or power dissipation. For example, the bicycle 100 may include a power meter 200 integrated with brake rotors 500 configured in the braking systems of the front wheel 79 and the rear wheel 78.

0045The power meter 200 may include an annular printed circuit board ("PCB") with strain measurement devices attached directly to the PCB. For example, the strain measurement device may be electrical resistance type strain gauges that are generally planar and/or laminar in construction with a layer of conductive metal formed in one or more patterns on a non-electrical substrate, film, paper, or other material. The conductive metal pattern or patterns may be formed of various metallic constructions, including foil and/or wire. The conductive metal pattern or patterns may be formed of any metal or metal alloy. For example, copper or copper alloys such as constantan may be used. Planar strain measurement devices also may include electrical contact connection surfaces configured for connection to circuitry of the PCB.

0046The PCB has a substrate to which components of the PCB are applied and/or attached. The substrate may form the structure and/or shape of the PCB. The substrate may be any substance operable to form the underlying attachment of the PCB components. For example, silicon, silicon dioxide, aluminum oxide, sapphire, germanium, gallium arsenide ("GaAs"), an alloy of silicon and germanium, or indium phosphide ("InP"), may be used. The substrate may be rigid or flexible. In an embodiment, the substrate forms an annular rigid ring. The rigid ring may be one continuous piece of substrate material. In an embodiment, a substrate ring has an inner diameter and an outer diameter defining the extents of the substrate there between. In an embodiment, a substrate ring has an inner diameter and an outer diameter defining the extents of the substrate there between. In an embodiment, the substrate may be sized, shaped, and/or otherwise configured to position strain measurement devices relative to a body of a bicycle component so as to measure torsional strain, such as the strain caused by the relative difference in rotation of an inner radial position of the body and an outer radial position of the body.

0047The connection to the circuitry of the PCB may be accomplished using any technique. In an embodiment, the connection is accomplished through an application of layer of a conductive medium, such as solder, between the electrical contact connection surfaces of the planar strain measurement device and contact connection surfaces of the PCB which provide electrically communicative contact with other electronic components connected to the PCB, such as a processor, memory, other sensors, and/or other electric or electronic devices. Such connection may be made directly, without the use of an intermediate conductive connector, such as an elongated electrical lead, wire, or other device. For example, the conductive medium may be bounded on opposing sides by the electrical contact connection surfaces of the PCB and strain measurement device. In this example, the electrical contact connection surfaces of the PCB and strain measurement device may be secured substantially parallel and opposing each other by the conductive medium. Further, as is described above, the connection may provide that the strain measurement device is fixably attached to the PCB substrate such that the strain measurement device is secure and not movable in a radial plane of the PCB substrate relative to other features and/or components of the PCB. As described herein, the PCB may be attached to a body of a drivetrain to form a power meter. Such a body may be any body having a torque input section and torque output section. For example, drive train components such as a chainring, a chainring carrier, a crank arm, a spindle, and/or a pedal may be used as a body for attachment of the PCB, or components of the PCB. Alternatively, the PCB may stand alone as the power meter.

0048<figref idref="f0004 f0005 f0006">Figures 2-4</figref> show a body, such as a chainring carrier and/or crank arm, of a bicycle drivetrain having an integrated power meter 200. The bicycle drivetrain may be the drivetrain 70 for the bicycle 100 of <figref idref="f0001">Figures 1A</figref> or <figref idref="f0002">1B</figref>. <figref idref="f0004">Figure 2</figref> shows a perspective view of the drivetrain components, <figref idref="f0005">Figure 3</figref> shows a top view of the drive train components, and <figref idref="f0006">Figure 4</figref> shows a bottom view, opposing that of <figref idref="f0005">Figure 3</figref>, of the bicycle components. In this embodiment, the body is a chainring carrier 77, or spider. The chainring carrier 77 may be made of any material operable to transmit torque, and a resulting power, between a torque input section (225 described below with respect to <figref idref="f0007 f0008 f0009 f0010 f0011">Figures 5-9</figref>) and a torque output section 222. For example, aluminum alloys may be used. A crank arm 75 is shown attached to the chainring carrier 77. The crank arm 75 has a pedal attachment section 102 to which a pedal 76 may be attached such that a bicycle rider may input pedaling forces into the bicycle drive train. These pedaling forces result in a torque that causes the crank arm 75 and attached chainring carrier to rotate about a crank or rotation axis 105. The crank arm 75 has a spindle attachment feature 108 that provides for attachment to a spindle that connects a crank arm and pedal assembly disposed on an opposing side of the bicycle to facilitate pedaling with both feet of the bicycle rider. The spindle attachment feature 108 may be any feature operable to transfer torque, such as a splined interface. As such, torque from either crank arm 75 may be transferred into the chainring carrier 77 through the crank arm 75 attachment to the chainring carrier 77. The crank arm 75 may be attached to the chainring carrier 77 using any technique operable to transmit torque between the crank arm 75 and a torque input section 225 of the chainring carrier 77. In an embodiment, the crank arm 75 is connected as is described in <patcit id="pcit0004" dnum="US20150082939"><text>U.S. Patent Application Publication 2015/0082939</text></patcit>.

0049For example, a crank arm 75 and chainring carrier 77 may be attached with corresponding features and with a distinct torque transmitting connection, such as with a bolted connection. In this example, the chainring carrier 77 is sized and shaped to connect to the crank arm 75. A first pairing feature 131 is formed on one of the crank arm 75 and the chainring carrier 77 and a second pairing feature 132 is formed on the other of the crank arm 75 and the chainring carrier 77 to position the chainring carrier on the crank arm. A clearance 133 is defined between the first and second pairing features 131, 132 when the first and second pairing features 131, 132 are paired. A torque-transmitting coupling 130, such as through bolted connection, is formed on the crank arm 75 and the chainring carrier 77 configured to transmit substantially all of the torque applied to the chainring carrier 77 from the crank arm 75.

0050A power meter cover 202 is provided to protect other power meter components installed within and/or on the body, such as a PCB assembly described below with respect to <figref idref="f0011 f0012 f0013 f0014">Figures 9-12</figref>. The power meter cover 202 may be constructed of any material operable to provide for the protection of the internal power meter 200 components. For example, aluminum alloys may be used. In an embodiment, the power meter 200 may communicate signals wirelessly and the power meter cover 202 may be made of a material that is radio frequency ("RF") transparent, such as polycarbonate or other materials. Also, a raised section 213 of a cover 212, as is illustrated in the embodiment shown in <figref idref="f0022 f0023 f0024 f0025 f0026">Figures 18-22</figref>, may be configured so as to cover an antenae and/or other wireless communication device of the power meter, and the raised section may be provided in an RF transparent material. Further, the raised section 213 may be formed of an RF transparent material and the rest of the cover may be formed of a material having a higher interference with RF signals, such as a metal or carbon fiber composite. The power meter cover 202 may be attached to the body, in this embodiment the chainring carrier 77, using any technique. For example adhesives may be used to attach the power meter cover 202. A power supply casing 204 is also provided to both secure and protect a power supply for the power meter 200. In an embodiment, the power supply casing 204 includes a removable power supply cover 205 to provide access to the power supply. A torque output section 222 is shown on the chainring carrier 77. Provided in the torque output section 222 in the displayed embodiment are torque output member attachment features 224, such as a plurality of bolt holes, which are configured to provide attachment to a chainring or other torque transmitting component of the bicycle drivetrain.

0051The chainring carrier 77 includes a strain measurement section 230, which may include one or more strain measurement features 232. The strain measurement features 232 are formed into the chainring carrier 77 to provide for positioning of strain measurement devices to detect and/or quantify mechanical deformations of the chainring carrier 77 due to torque applied between the torque input section 225 and the torque output section 222. For example, the strain measurement devices may be electrical resistance type strain gauges attached to the strain measurement features 232.

0052<figref idref="f0007 f0008 f0009 f0010 f0011">Figures 5-9</figref> show the chainring carrier 77 of <figref idref="f0004 f0005 f0006">Figures 2-4</figref>. <figref idref="f0007">Figure 5</figref> illustrates an exploded view of the chainring carrier 77 and other components of the power meter 200. <figref idref="f0008">Figure 6</figref> shows a perspective view of the chainring carrier 77. <figref idref="f0009">Figure 7</figref> shows a perspective view of the chainring carrier 77 with the power meter cover 202 removed. <figref idref="f0010">Figure 8</figref> shows a top view of the chainring carrier 77 with the power meter cover 202 removed, and <figref idref="f0011">Figure 9</figref> shows the same top view of the chainring carrier 77 with the power supply components hidden from view. As used herein, a power meter may include various components. In an embodiment, a power meter may include all of the components indicated in <figref idref="f0007">Figure 5</figref>. More or fewer components may be included in the power meter 200. For example, the power meter may be the components of <figref idref="f0007">Figure 5</figref>, without the chainring carrier 77.

0053As shown in <figref idref="f0007">Figures 5</figref> and <figref idref="f0009 f0011">7-9</figref> the chainring carrier 77 includes a cavity 207 configured for installation of the PCB assembly 250 and/or other power meter 200 components. The cavity 207 may include an alignment feature 209 which corresponds to substrate alignment feature 254 formed in a substrate 252 of the PCB assembly 250. As can be seen in <figref idref="f0011">Figure 9</figref>, wherein the power supply components are hidden from view, through the correlation of these alignment features 254, 209 the PCB assembly 250 may be appropriately aligned with the chainring carrier 77. Other alignment features may also be used and/or formed into the PCB substrate 252.

0054The PCB assembly 250 also includes a plurality of strain measurement devices 260 attached to the substrate 252 and/or other parts of the PCB assembly 250. The strain measurement devices 260 are configured to provide a signal indicative of strain in an attached body. The signal may be interpreted and acted upon by circuitry 28 of the power meter, for example as is described with respect to the power meter system 40 of <figref idref="f0021">Figure 17</figref>. The circuitry 28 may be configured to interpret the signal indicative of strain, and calculate a corresponding mechanical power being transmitted through the attached body.

0055In the displayed embodiment the strain measurement devices 260 are attached at strain measurement device attachment features 258 formed in the substrate 252. Further features and/or characteristics of the PCB assembly 250 are discussed below with respect to <figref idref="f0012 f0013 f0014">Figures 10-12</figref>.

0056In the displayed embodiment, the strain measurement device attachment features 258 form a vacancy or void. The void may provide access to the strain measurement devices 260 in an axial direction of the PCB assembly 250, such as along a direction of the axis of rotation 105. This access may be used during installation of the PCB assembly 250 into a body such as the chainring carrier 77. For example, to generate a quality attachment of the strain measurement devices 260 a clamp may be used for attachment to the body during a curing process. As shown, the strain measurement device attachment features 258 are configured to allow the attachment of the strain measurement devices 260 so that the strain measurement devices do not protrude beyond an inner diameter 251 of the substrate 252. This configuration may provide for a maximized substrate 252 surface area available for circuitry implementation, but a minimized total surface area of the PCB assembly, particularly in an annular substrate implementation wherein such a configuration may optimize and/or minimize the radial extents of the PCB assembly installation. Further, the strain measurement device attachment features 258 may be disposed so as to circumferentially correlate with bolt holes 224 of the torque output section 222. For example, the device attachment features 258 may be circumferentially separated by an angle θ. In an embodiment, the angle θ may be 10 degrees to 20 degrees. In an embodiment, a number of strain measurement device attachment features matches a number of strain measurement features and/or bolt holes 224 of a torque output section 222.

0057As shown, the strain measurement devices 260 are attached at a radially inner edge of the substrate 252. Alternatively, the strain measurement devices 260 may be attached at a radially out edge of the substrate 252, or between the radially inner and radially outer edge of the substrate 252.

0058The power supply for the power meter 200 is attached both physically and electrically using a contact structure 206 and a metallic screw 203. As shown, the alignment feature 209 also provide for the attachment of the power supply for the power meter 200 using the metallic screw 203. Alignment features may be provided without facilitation for power supply attachment as well.

0059<figref idref="f0012 f0013 f0014">Figures 10-12</figref> show the PCB assembly 250 of the power meter 200. <figref idref="f0012">Figure 10</figref> shows a top perspective view of the PCB assembly 250. <figref idref="f0013">Figure 11</figref> shows a top view of the PCB assembly 250, and <figref idref="f0014">Figure 12</figref> shows a bottom perspective view of the PCB assembly 250. The PCB assembly 250 includes circuitry 28 as is described further with respect to <figref idref="f0021">Figure 17</figref> below. The circuitry 28 may involve one or more processors 20, as well as other electric and/or electronic components as well as additional sensors 93, such as an accelerometer. The circuitry may also include one or more antennae 290 as part of the communication interface 90. Additional or alternative alignment features 255, 256 used for aligning the PCB assembly 250 to a body of a bicycle drivetrain may be formed into the substrate 252 of the PCB. For example, one or more notches 255 may be cut into an interior and/or exterior edge of the substrate 252. The notches 255 may be configured to correspond to corollary features of the body to which the PCB assembly 250 is to be attached. Also, one or more holes 256 may be formed in the substrate 252 which may be used by an assembly tool or handler to specifically attach to the PCB assembly 250 in a particular orientation. The tool and/or handler may then be aligned to the body to which the PCB assembly is to be attached such that the PCB assembly 250 is aligned properly to the body. For example, the alignment features 256, 255, 254 may be used independently or in combination to align the one or more strain measurement devices 260 to the body.

0060The substrate 252 operates to connect, and/or provide structure for the circuitry and attached components of the PCB assembly 250. The substrate 252 may be flexible or rigid. In an embodiment, the substrate 252 is a rigid substrate providing a durable basis for the PCB assembly 250. The substrate 252 is formed to provide shape and other substance for the PCB assembly 250. For example, as shown, the substrate 252 is formed in an annular construction and/or shape. Such an annular shape facilitates installation of the PCB assembly 250 around a torque input section of a body.

0061At least one strain measurement device 260 may be attached to the PCB assembly 250 such that the at least one strain measurement device 260 is fixed in a plane P of the PCB assembly 250 relative to at least one feature of the PCB assembly 250. For example, the strain measurement devices 260 may be fixed relative to one or more of the alignment features 254, 255, 256 and/or a circuitry 28 component such as the processor 20. The plane P may be a plane formed to include the substrate 252. In an embodiment, the plane P is perpendicular to the axis of rotation 105. An annular construction of the substrate 252, and rigid attachment of the strain measurement devices 260 as described above, provides for the disposition of a plurality of strain measurement devices 260 around the annular shape and about the torque input section. Such an annular construction also allows for the disposition of the strain measurement devices between the torque input section and the torque output section.

0062<figref idref="f0015">Figures 13</figref>, <figref idref="f0016">14A</figref>, and <figref idref="f0017">14B</figref> show an embodiment having a power meter 200 integrated with a chainring 300. <figref idref="f0015">Figure 13</figref> illustrates an exploded view of the chainring 300, <figref idref="f0016">Figure 14A</figref> shows a perspective view of the chainring 300 with the power meter cover 202 removed, and <figref idref="f0017">Figure 14B</figref> shows a top view of the chainring 300 with the cover 202 removed.

0063The chainring 300 includes a PCB assembly installation section 305. The chainring also includes a torque input section 325, configured similarly to the torque input section 225 described above with regard to the chainring carrier 77. The chainring 300 also includes a torque output section 322 that includes a plurality of teeth 323 configured to operationally interact with, and transmit torque to, a bicycle chain, such as the bicycle chain 72 described with respect to <figref idref="f0001">Figures 1A</figref> and <figref idref="f0002">1B</figref>. The displayed embodiment also includes a PCB assembly 250, a power meter cover 202, and power supply components 204, 205 of the power meter 200.

0064<figref idref="f0018">Figure 15</figref> shows an embodiment similar to the embodiment shown in <figref idref="f0015">Figures 13</figref>, <figref idref="f0016">14A</figref>, and <figref idref="f0017">14B</figref>, but the torque output section 322 includes two pluralities of teeth 323A and 323B disposed as different drive sprockets for the drivetrain.

0065<figref idref="f0022 f0023 f0024 f0025 f0026">Figures 18-22</figref> show an embodiment having the power meter 200 integrated with a brake rotor 500, for example the brake rotor of <figref idref="f0002">Figure 1B</figref>. <figref idref="f0022">Figure 18</figref> shows a perspective view of the brake rotor 500, <figref idref="f0023">Figure 19</figref> shows a front view of the rotor 500, <figref idref="f0024">Figure 20</figref> shows a back view of the rotor 500, <figref idref="f0025">Figure 21</figref> shows an exploded perspective view from the front of the brake rotor 500 with a rotor carrier 577 or spider also exploded to show the PCB 250 of the power meter 200, and <figref idref="f0026">Figure 22</figref> shows an exploded perspective view from the back of the brake rotor 500 with an assembled carrier 577.

0066The brake rotor 500 includes a rotor carrier 577 and an annular rotor structure 580 attached and/or attachable to the rotor carrier 577. The annular rotor structure 580 includes a friction or braking surface 502 configured for the application of braking forces, for example with the caliper 94 of <figref idref="f0002">Figure 1B</figref>. The annular rotor structure 580 also includes a rotor attachment section 561 which may include one or more rotor attachment features 562, such as a hole 564 with supporting structure and/or surfaces, configured for attachment to one or more corresponding carrier attachment features 526 of the rotor carrier 577. The carrier attachment features may include a hole and/or a wall or surface configured to receive and/or secure to corresponding structure of the rotor attachment features 562. In the illustrated embodiment, the annular rotor structure 580 and the rotor carrier 577 are attached using fasteners 540, which may include a fastener system such as a screw 540B and corresponding nut 540A. Alternate forms of fastener and attachment are also possible, such as with rivets, adhesives, interlocking features, or other devices and/or techniques.

0067The rotor attachment section 561 may include an attachment section ring 563 connecting the rotor attachment features 562. The carrier attachment features 526 may include a carrier attachment surface and a carrier attachment hole 528 configured to attach and or otherwise couple to the rotor attachment features 562 of the annular rotor structure 580.

0068The annular rotor structure 580 may also include arms 504 or connectors between the friction surface 502 and the rotor attachment features 562 and/or the rotor attachment section 561. The arms 504 extend in the radial direction. In the embodiment shown, the arms 504 are distributed about the annular structure transferring loads between the friction surface 502 and the rotor attachment features 562 and/or the rotor attachment section 561. To account for thermal expansion and contraction as well as possible load deflections of the annular rotor structure 580 the arms 504 may extend radially, but be slanted about the circumference of the structure.

0069The rotor carrier 577 includes a torque input section 525 and a torque output section 522. In the illustrated embodiment the torque input section 525 is at the radially innermost portion of the rotor carrier 577, and the torque output section 522 at the radially outermost section of the rotor carrier 577. The PCB 250 of the power meter 200 is disposed radially between the torque input section 525 and the torque output section 522. The torque output section 522 includes the carrier attachment features 526. Similar to the chainring carrier described herein, the rotor carrier 577 also may include a strain measurement section 530. The strain measurement section 530 includes strain measurement features 532 configured to facilitate the measurement of strain through in the strain measurement section 530 using the strain measurement devices 260 of the power meter 200. The PCB assembly 250 of the power meter 200 may be aligned to the strain measurement features 532 using an alignment feature 509 that corresponds to the substrate alignment feature 254. Also, in this embodiment, the power meter cover 212 is similar to the power meter cover 202 previously described, but includes a raised or clearance section 213. The raised section 213 may be configured to provide clearance for circuitry of the PCB assembly 250. For example, the PCB assembly 250 may include an antennae or other wireless communication device, having height that extends beyond the clearance provide by the rest of the cover 212. The raised section 213 may provide additional clearance for this extended height.

0070The rotor carrier 577 may also include heat dissipation features 578, such as ribs or other features configured for dissipating heat generated by the application of the friction force to the friction surface 502.

0071In the embodiment shown in <figref idref="f0022 f0023 f0024 f0025 f0026">Figures 18-22</figref>, the power meter 200 is integrated with the rotor carrier, similar to the integration of the power meter 200 with the chainring carrier 77 described herein. In an embodiment, the power meter 200 may be integrated with a brake rotor with an integrated carrier, or no carrier.

0072<figref idref="f0019">Figures 16A</figref> and <figref idref="f0020">16B</figref> illustrate close up views of the attachment of the strain measurement devices 260 to the substrate 252 of the PCB and the body 401. A volume of electrically conductive bonding material 405, for example a fusible metal alloy such as tin, lead, brass, or silver based solder, is disposed between planar electrical contact surfaces 420 of the strain measurement device 260 and electrical circuitry contacts 422 that are communicatively coupled to circuitry 28 of the PCB assembly. The volume of electrically conductive bonding material 405 involves at least one distinct volume of electrically conductive bonding material, and the electrical circuitry contacts 422, and/or the substrate 252, and the at least one strain measurement device 260 are in physical contact with the distinct volume of electrically conductive bonding material 405. The electrical circuitry contacts 422 may be embedded in the substrate 252.

0073The strain measurement device 260 may be laminar, and formed of multiple layers. A base layer 432 may be formed to provide an attachment surface to be attached to the body 401 and a base insulative layer for conductive material 427 of the strain measurement patterns and/or the electrical contact surfaces 420 of the strain measurement device 260. A cover layer 429 may be included to cover the conductive material 427 layer. The cover layer 429 may not exist in an area of the electrical contact surfaces 420 so as to leave the contact surfaces available for electrical connection. The strain measurement patterns are disposed in a section 441 to be attached to the body 401. In the displayed embodiment, the section 441 is to be disposed generally flat and parallel to the correlating surface of the body 401.

0074The strain measurement device 260 is attached to the body 401 with an attachment material 425 that is appropriately rigid to transmit the deformation of the body in a measurable way to the strain measurement device 260, but also resilient enough to avoid cracking or otherwise breaking down due to repetitive deformation of the body. In an embodiment an adhesive, such as a cyanoacrylate based adhesive, is used. Polyester, Phenol, and/or epoxy based adhesives may also be used.

0075The PCB assembly and/or the substrate may be attached to the body using any technique. In the displayed embodiment, a material 417 such as a double sided adhesive tape, for example a foam adhesive tape, may be used to secure the PCB assembly to the body 401. Such attachment may provide for thermal and mechanical deformations of the body 401 to be isolated from the PCB assembly. Such attachment mechanisms, however, may cause the substrate 252 to which the strain measurement device 260 is attached, to have a significant void to be filled between the strain measurement device 260 and the body 401. This void may be filled with the strain measurement device attachment material 425, however, the configuration may apply stresses to the strain measurement device 260 that can cause buckling or other breakages of the conductive material layer of the strain measurement device 260.

0076To help alleviate this configuration issue, the strain measurement device 260 may also be attached to the substrate 252 of the PCB assembly with a structural support material 415. The structural support material 415 is configured to provide structural rigidity to the strain measurement device 260 as the device is deformed to form a connection with the body 401. A structural support fillet or other structure may be formed by the structural support material 415. The structural support material 415 may be disposed so as to be connected to the substrate 252 and the cover layer 429 of the strain measurement device 260. In an embodiment, the structural support material 415 maintains an edge of the substrate and at least a portion of the strain measurement device 260 in a generally orthogonal or perpendicular orientation. The structural support material 415 may be any material operable to provide the requisite rigidity. For example, an ultra-violet light curable adhesive may be used.

0077<figref idref="f0021">Figure 17</figref> is a block diagram of an exemplary power meter system 40 for a bicycle. The system 40 may be used alone to communicate with and/or control bicycle components or other devices. The system 40 includes circuitry 28 which includes at least one processor 20 and a memory 10. In the illustrated embodiment, the circuitry 28 also includes a user interface 82, a strain detection device interface 80, and a communication interface 90. Circuitry 28 may also include component connections and/or electrically connecting materials embedded in a substrate material. The system also includes at least one strain detection device 260 in communication with the strain detection device communication interface 80. Additional, different, or fewer components are possible for the power meter system 40. For example, the user interface 82 may not be included in a circuitry 28 and/or the power meter system. Also, components may be combined. In an embodiment, the power meter system is integrated with a component of a power train of a bicycle, such as a chainring or chainring carrier, for example as is described with respect to <figref idref="f0004 f0005 f0006 f0007 f0008 f0009 f0010 f0011 f0012 f0013 f0014 f0015 f0016 f0017 f0018 f0019 f0020">Figures 2 - 16</figref>.

0078The processor 20 may include a general processor, digital signal processor, an application specific integrated circuit (ASIC), field programmable gate array (FPGA), analog circuit, digital circuit, combinations thereof, or other now known or later developed processor. The processor 20 may be a single device or combinations of devices, such as through shared or parallel processing.

0079The circuitry 28 is operable to interpret a signal indicative of strain from deformation of an attached body from one or more of the strain detection devices 260 and determine a corresponding power transmitted between the torque input and the torque output section. For example, the signal may be communicated from the strain detection devices 260 to the processor 20 which may apply a conversion technique of the strain to a power transmitted across the body for a time period. Such a conversion technique may involve using the known material characteristics of the body, such as the modulus of elasticity and a known geometry of the body. Force values to cause amounts of strain measurable by the strain detection devices 260 may be known from these, or other, characteristics of the power meter system. For example, these values, or indications of these values, may be stored on a memory 10. The measured strain values may be matched against these values by the processor 20 to determine an input force, and a resulting power over time transmitted by the body of the drive train.

0080The memory 10 may be a volatile memory or a non-volatile memory. The memory 10 may include one or more of a read only memory (ROM), random access memory (RAM), a flash memory, an electronic erasable program read only memory (EEPROM), or other type of memory. The memory 10 may be removable from the power meter system 40, such as a secure digital (SD) memory card. In a particular non-limiting, exemplary embodiment, a computer-readable medium can include a solid-state memory such as a memory card or other package that houses one or more non-volatile read-only memories. Further, the computer-readable medium can be a random access memory or other volatile rewritable memory. Additionally, the computer-readable medium can include a magnetooptical or optical medium, such as a disk or tapes or other storage device. Accordingly, the disclosure is considered to include any one or more of a computer-readable medium and other equivalents and successor media, in which data or instructions may be stored.

0081The memory 10 is a non-transitory computer-readable medium and is described to be a single medium. However, the term "computer-readable medium" includes a single medium or multiple media, such as a centralized or distributed memory structure, and/or associated caches that are operable to store one or more sets of instructions and other data. The term "computer-readable medium" shall also include any medium that is capable of storing, encoding or carrying a set of instructions for execution by a processor or that cause a computer system to perform any one or more of the methods or operations disclosed herein.

0082In an alternative embodiment, dedicated hardware implementations, such as application specific integrated circuits, programmable logic arrays and other hardware devices, can be constructed to implement one or more of the methods described herein. Applications that may include the apparatus and systems of various embodiments can broadly include a variety of electronic and computer systems. One or more embodiments described herein may implement functions using two or more specific interconnected hardware modules or devices with related control and data signals that can be communicated between and through the modules, or as portions of an application-specific integrated circuit. Accordingly, the present system encompasses software, firmware, and hardware implementations.

0083The power supply 84 is a portable power supply. The power supply may involve the generation of electric power, for example using a mechanical power generator, a fuel cell device, photo-voltaic cells, or other power generating devices. The power supply may include a battery such as a device consisting of two or more electrochemical cells that convert stored chemical energy into electrical energy. The power supply 84 may include a combination of multiple batteries or other power providing devices. Specially fitted or configured battery types, or standard battery types such as CR 2012, CR 2016, and/or CR 2032 may be used.

0084The communication interface 90 provides for data and/or signal communication from the power meter system 40 to another component of the bicycle, or an external device such as a mobile phone or other computing device. The communication interface 90 communicates the data using any operable connection. An operable connection may be one in which signals, physical communications, and/or logical communications may be sent and/or received. An operable connection may include a physical interface, an electrical interface, and/or a data interface. The communication interface 90 may be configured to communicate wirelessly, and as such include one or more antennae. The communication interface 90 provides for wireless communications in any now known or later developed format. Although the present specification describes components and functions that may be implemented in particular embodiments with reference to particular standards and protocols, the invention is not limited to such standards and protocols. For example, standards for Internet and other packet switched network transmission (e.g., TCP/IP, UDP/IP, HTML, HTTP, HTTPS) represent examples of the state of the art. Such standards are periodically superseded by faster or more efficient equivalents having essentially the same functions. Bluetooth® and or ANT+™ standards may also, or alternatively, be used. Accordingly, replacement standards and protocols having the same or similar functions as those disclosed herein are considered equivalents thereof. In an embodiment, the communication interface 90 may be configured to transmit a signal indicative of a power determined from a measured strain of a body. Further, the determined power may be transmitted wirelessly.

0085The strain detection device interface 80 provides for data and/or signal communication from one or more strain detection devices 260 to the power meter circuitry 28. The interface 80 communicates using wired and/or wireless communication techniques. For example, the interface 80 communicates with the strain detection devices 260 using a system bus, or other communication technique. The strain detection device interface 80 may include additional electric and/or electronic components, such as an additional processor and/or memory for detecting, communicating, and/or otherwise processing signals of the strain detection devices 260.

0086The user interface 82 may be one or more buttons, keypad, keyboard, mouse, stylus pen, trackball, rocker switch, touch pad, voice recognition circuit, or other device or component for communicating data between a user and the power meter system 40. The user interface 82 may be a touch screen, which may be capacitive or resistive. The user interface 82 may include a liquid crystal display ("LCD") panel, light emitting diode ("LED"), LED screen, thin film transistor screen, or another type of display. The user interface 82 may also include audio capabilities, or speakers.

0087In an embodiment, the user interface 82 includes an LED indicator. The LED indicator lights to indicate input of the commands or other actions of the power meter system.

0088The communication interface 90 is configured to send and/or receive data such as control signals and/or commands to and/or from bicycle components such as the front gear changer 30 and/or the shift units 26. The component communication interface 90 communicates the data using any operable connection. An operable connection may be one in which signals, physical communications, and/or logical communications may be sent and/or received. An operable connection may include a physical interface, an electrical interface, and/or a data interface. The communication interface 90 provides for wireless communications in any now known or later developed format. Although the present specification describes components and functions that may be implemented in particular embodiments with reference to particular standards and protocols, the invention is not limited to such standards and protocols. For example, standards for Internet and other packet switched network transmission (e.g., TCP/IP, UDP/IP, HTML, HTTP, HTTPS) represent examples of the state of the art. Such standards are periodically superseded by faster or more efficient equivalents having essentially the same functions. Accordingly, replacement standards and protocols having the same or similar functions as those disclosed herein are considered equivalents thereof.

0089In accordance with various embodiments of the present disclosure, methods described herein may be implemented with software programs executable by a computer system, such as the circuitry 28. Further, in an exemplary, non-limited embodiment, implementations can include distributed processing, component/object distributed processing, and parallel processing. Alternatively, virtual computer system processing can be constructed to implement one or more of the methods or functionality as described herein.

0090A computer program (also known as a program, software, software application, script, or code) can be written in any form of programming language, including compiled or interpreted languages, and it can be deployed in any form, including as a standalone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. A computer program does not necessarily correspond to a file in a file system. A program can be stored in a portion of a file that holds other programs or data (e.g., one or more scripts stored in a markup language document), in a single file dedicated to the program in question, or in multiple coordinated files (e.g., files that store one or more modules, sub programs, or portions of code). A computer program can be deployed to be executed on one computer or on multiple computers that are located at one site or distributed across multiple sites and interconnected by a communication network.

0091The processes and logic flows described in this specification can be performed by one or more programmable processors executing one or more computer programs to perform functions by operating on input data and generating output. The processes and logic flows can also be performed by, and apparatus can also be implemented as, special purpose logic circuitry, e.g., an FPGA (field programmable gate array) or an ASIC (application specific integrated circuit).

0092As used in this application, the term 'circuitry' or 'circuit' refers to all of the following: (a)hardware-only circuit implementations (such as implementations in only analog and/or digital circuitry) and (b) to combinations of circuits and software (and/or firmware), such as (as applicable): (i) to a combination of processor(s) or (ii) to portions of processor(s)/software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and (c) to circuits, such as a microprocessor(s) or a portion of a microprocessor(s), that require software or firmware for operation, even if the software or firmware is not physically present.

0093This definition of 'circuitry' applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term "circuitry" would also cover an implementation of merely a processor (or multiple processors) or portion of a processor and its (or their) accompanying software and/or firmware, as well as other electronic components. The term "circuitry" would also cover, for example and if applicable to the particular claim element, a baseband integrated circuit or applications processor integrated circuit for a mobile computing device or a similar integrated circuit in server, a cellular network device, or other network device.

0094Processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer. Generally, a processor receives instructions and data from a read only memory or a random access memory or both. The essential elements of a computer are a processor for performing instructions and one or more memory devices for storing instructions and data. Generally, a computer also includes, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., magnetic, magneto optical disks, or optical disks. However, a computer need not have such devices. Moreover, a computer can be embedded in another device, e.g., a mobile telephone, a personal digital assistant (PDA), a mobile audio player, a Global Positioning System (GPS) receiver, or a power meter system 40 to name just a few. Computer readable media suitable for storing computer program instructions and data include all forms of non-volatile memory, media and memory devices, including by way of example semiconductor memory devices, e.g., EPROM, EEPROM, and flash memory devices; magnetic disks, e.g., internal hard disks or removable disks; magneto optical disks; and CD ROM and DVD-ROM disks. The processor and the memory can be supplemented by, or incorporated in, special purpose logic circuitry.

0095In an embodiment, a power meter for a bicycle includes a body comprising a torque input section and a torque output section, the body configured to transmit power between the torque input section and the torque output section. The power meter also includes a printed circuit board ("PCB"). The PCB includes a substrate, at least one strain measurement device attached to the substrate, the at least one strain measurement device configured to provide a signal indicative of strain detected in the body, and circuitry, embedded in the substrate, the circuitry configured for interpreting the signal and determining a corresponding power transmitted between the torque input and the torque output section. In an embodiment, the at least one strain measurement device may be attached to the substrate such that the at least one strain measurement device is fixed in a plane of the PCB relative to at least one feature of the PCB. In an embodiment, the feature is formed in the substrate. In an embodiment, the at least one strain measurement device may be a foil or wire type electrical strain gauge. In an embodiment, the torque output section may include teeth. In an embodiment, the torque output section may include chainring attachment features. In an embodiment, the at least one strain measurement device may include planar electrical contact surfaces, and the PCB may be configured such that the strain measurement device planar electrical contact surfaces are disposed facing electrical circuitry contacts of the PCB, the electrical circuitry contacts of the PCB communicatively coupled to both the strain measurement device planar electrical contact surfaces and the circuitry of the PCB. In an embodiment, the at least one strain measurement device may be communicatively coupled to the circuitry of the PCB with a volume of an electrically conductive bonding material. In an embodiment, the electrically conductive bonding material may be a fusible metal alloy. In an embodiment, the volume of electrically conductive bonding material may include at least one distinct volume of electrically conductive bonding material, and both the PCB and the at least one strain measurement device are in physical contact with the distinct volume of electrically conductive bonding material. In an embodiment, the at least one strain measurement device may be attached to the body with an adhesive. In an embodiment, the at least one strain measurement device attachment to the PCB may include a structural support material. In an embodiment, the structural support material may be disposed both on an edge of the substrate and on a surface of the at least one strain measurement device. In an embodiment, the edge and the surface are oriented substantially orthogonal to each other. In an embodiment, the substrate may be of annular construction and disposed in the body around the torque input section. In an embodiment, the at least one strain measurement device may include a plurality of strain measurement devices disposed about the torque input section. In an embodiment, the plurality of strain measurement devices may be disposed so as to align with strain measurement features of the body. In an embodiment, the substrate includes at least one strain measurement device attachment feature, and the at least one strain measurement device may be disposed on the substrate so as to be aligned with the at least one strain measurement device attachment feature. In an embodiment, the strain measurement device attachment feature may include at least one vacancy formed in the substrate. In an embodiment, the vacancies are configured to provide access to the at least one strain measurement device in an axial direction of the PCB. In an embodiment, the body further may include bolt holes in the torque output section configured for attachment to a chainring, and the strain measurement device attachment features are disposed so as to correlate to the bolt holes. In an embodiment, the power meter may include a same number of strain measurement features and bolt holes. In an embodiment, the circuitry may be further configured to wirelessly transmit a second signal indicative of the determined power.

0096In an embodiment a brake rotor includes a rotor carrier having a torque input section, and a torque output section. The brake rotor also includes a printed circuit board ("PCB") that includes a substrate, at least one strain measurement device, the at least one strain measurement device configured to provide a signal indicative of strain detected in the rotor carrier, and circuitry, attached to the substrate, the circuitry configured for interpreting the signal and determining a corresponding power transmitted between the torque input and the torque output section. The brake rotor also includes an annular rotor structure attached to the torque output section of the rotor carrier and having at least one friction surface configured for generating friction to dissipate power provided at the torque input section of the carrier. The carrier may also include heat dissipation features.

0097The illustrations of the embodiments described herein are intended to provide a general understanding of the structure of the various embodiments. The illustrations are not intended to serve as a complete description of all of the elements and features of apparatus and systems that utilize the structures or methods described herein. Many other embodiments may be apparent to those of skill in the art upon reviewing the disclosure. Other embodiments may be utilized and derived from the disclosure, such that structural and logical substitutions and changes may be made without departing from the scope of the disclosure. Additionally, the illustrations are merely representational and may not be drawn to scale. Certain proportions within the illustrations may be exaggerated, while other proportions may be minimized. Accordingly, the disclosure and the figures are to be regarded as illustrative rather than restrictive.

0098While this specification contains many specifics, these should not be construed as limitations on the scope of the invention or of what may be claimed, but rather as descriptions of features specific to particular embodiments of the invention. Certain features that are described in this specification in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable sub-combination. Moreover, although features may be described above as acting in certain combinations and even initially claimed as such, one or more features from a claimed combination can in some cases be excised from the combination, and the claimed combination may be directed to a sub-combination or variation of a sub-combination.

0099Similarly, while operations and/or acts are depicted in the drawings and described herein in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Moreover, the separation of various system components in the embodiments described above should not be understood as requiring such separation in all embodiments, and it should be understood that any described program components and systems can generally be integrated together in a single software product or packaged into multiple software products.

0100One or more embodiments of the disclosure may be referred to herein, individually and/or collectively, by the term "invention" merely for convenience and without intending to voluntarily limit the scope of this application to any particular invention or inventive concept. Moreover, although specific embodiments have been illustrated and described herein, it should be appreciated that any subsequent arrangement designed to achieve the same or similar purpose may be substituted for the specific embodiments shown. This disclosure is intended to cover any and all subsequent adaptations or variations of various embodiments. Combinations of the above embodiments, and other embodiments not specifically described herein, are apparent to those of skill in the art upon reviewing the description.

0101The Abstract of the Disclosure is provided to comply with 37 C.F.R. §1.72(b) and is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the foregoing Detailed Description, various features may be grouped together or described in a single embodiment for the purpose of streamlining the disclosure. This disclosure is not to be interpreted as reflecting an intention that the claimed embodiments require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter may be directed to less than all of the features of any of the disclosed embodiments. Thus, the following claims are incorporated into the Detailed Description, with each claim standing on its own as defining separately claimed subject matter.

0102It is intended that the foregoing detailed description be regarded as illustrative rather than limiting and that it is understood that the following claims are intended to define the scope of the invention.