PowerTap Frequently Asked Questions

Questions about your PowerTap cycling power meter, cycling computer or accessory? We’re here to help, from product manuals to instructional videos.

Training with power can be heady stuff. No one expects you to have all the answers. In fact, you’re bound to have some burning questions along the way – from how to train with power to choosing the right product to getting the most out of your power-training system. No worries. We’ll keep you training smart and riding fast.

Where can I find parts drawings for my PowerTap power meter?

How do I update my G3 hub's firmware?

As of 4/22/14 you can update the Powercap on a Mac with PowerAgent 7.7.5

Video instructions are available HERE.

  • Spin the wheel/axle a couple times with the Powercap still on to “wake up” the Powercap
  • Take Powercap off by removing the triangular nut and pulling Powercap straight off (do NOT twist)
  • Remove the CR2032 battery from the Powercap
  • Plug the Powercap without the battery into your computer using a micro USB cable
  • Open PowerAgent
  • Navigate to Tools > Firmware > Check for Firmware Update
  • Click OK to begin the firmware update
  • Firmware will install. With some new versions of firmware, Window OS will need to “re-find” the attached PowerCap. Let it run to completion.
  • When PowerAgent says the update was successful, click OK and unplug Powercap
  • Wait 10 seconds, plug battery back into the Powercap
  • Install PowerCap back on PowerTap hub

Does the G3 have a Rechargeable Battery?

The G3 PowerCap is not rechargeable. The PowerCap uses a standard coin cell CR2032 battery. The USB connection is used for service and for firmware updates only. The PowerCap should not be left connected to the USB port for long periods. Doing so could drain the battery.

Will The G3 hub work with a Yellow Cervo CPU?

No, the G3 hub is now fully ANT+ compatible and will only work with the Joule or other ANT+ compatible device. The Bluetooth SMART PowerCap accessory can be used to connect to compatible smart devices.The previous Plus series hubs still sent a signal on the PowerTap (formerly CycleOps) network that the Yellow CPU used. That signal is no longer sent by the G3 hub; however, the Pro hub does still work with the Yellow CPU.

What length spokes do I need to build my new PowerTap G3 hub into my rim?

You will need to enter the rim measurements, along with the correct PowerTap hub dimensions shown below, and the cross pattern into a spoke calculator to determine the necessary spoke length. For additional questions please contact your local PowerTap dealer.

Measurements Drive Non-Drive
15mm Axle
Wheel center to flange
17.4mm 38.0mm
Flange Diameter 57.0mm 57.0mm
Spoke hole diameter 2.5mm 2.5mm
Hub must be laced with minimum 2X pattern

What length spokes do I need to build my new PowerTap GS hub into my rim?

Download our GS Spoke Length Chart

For additional questions please contact your local PowerTap dealer.

Why do I get intermittent data transmission?

Batteries may need replacement in the hub. With older generation hubs like the SL+ and Pro+, make sure that the battery holder is seated properly in the hub. For the G3 you may also want to make sure that the PowerCap firmware is up-to-date.

Which phones or tablets work with the BLE PowerCap?

For phones you can use the iphone 4S, 5, 5S, or 5C. Iphone 4 and lower does not have integrated Bluetooth 4.0. The BLE PowerCap will work with ipad 3 or higher tablets and Android tablets with Jelly Bean OS 4.3 or higher.

View more information about which products are compatible with Bluetooth Smart.

Do you have a crash replacement policy?

3-Year Wheel Crash Replacement Policy

Although not a popular subject, the last thing we want you to have to worry about while riding is crashing. Damage to you and your equipment can be physically and emotionally painful. And while we can’t help the road rash heal more quickly, we can put your mind at rest with our 3-year crash replacement policy on our wheels.

Simply put: if your PowerTap wheels need to be replaced within 3 years of purchase, PowerTap will replace your wheel(s) at 50% off MSRP. There: now you no longer have to worry about ruining those sweet wheels, so get out and ride and ride hard.

Now, there’s a bit of fine print, which we’ve outlined below in a font size which is easy to read. This policy only applies to wheels purchased new from PowerTap.com or an authorized PowerTap dealer, and does not cover:

  • Normal wear and tear.
  • Any intentional damage, misuse, neglect, abuse, improper assembly, improper maintenance, or failure to follow instructions or warnings in User Guide.
  • Use of products in a manner or environment for which they were not designed.
  • Damage due to using incorrect brake pads.
  • Must provide original sales receipt or proof of purchase.
  • This policy is only valid for original owners of PowerTap Wheel(s).

Please call our PowerTap support line at (800) 246-5975 for crash replacement assistance.

Why do I have no display on my computer?

  • The computer may be asleep. Press one of the buttons on the computer to wake up the computer.
  • Batteries need replacement or charging
  • Is the computer too cold? Optimum operating temperature is 30-100 degrees Fahrenheit.
  • Battery contact inside the Joule may be depressed. Remove the battery cover and battery to expose the silver battery contact. There should be sufficient spring in this tab. If there is not, GENTLY pull up on the contact to reform it.

My Joule GPS reads my PowerTap or PowerCal, but falls asleep after a couple minutes?

Make sure to check the record control on the Joule. Go to the main menu under device memory. You can set the Joule to start recording by speed or heart rate.

How much memory does the PowerTap computer have available?

  • Joule has about 20 hrs of total memory
  • Joule GPS has about 80 hrs of total memory

When riding, why does my cadence show all dashes or zeros?

  • PowerTap cadence is accurate within 40 rpm and 130 rpm. Anything outside of this range will be recorded as a zero. Since the cadence measurement is a virtual cadence (based off of torque measurements) and not measured with an extra sensor it cannot read values outside of this range.
  • If you’re using the cadence separate cadence sensor, make sure the sensor is paired to the computer and that magnets are lined up properly. Magnet and sensor should be about 2mm away from each other when they pass.

Why isn't my PowerTap computer showing watts?

  • Ensure the hub is awake by spinning the rear wheel. Perform a “find” on the on the Joule/Joule GPS by pressing and holding the “+” and “-” buttons for 3 seconds. Spin the wheel to wake up the PowerTap.
  • Zero the torque (see our video instructions for Joule GPS and Joule).

Why won't my Joule recognize my G3 hub?

Update your Joule and PowerCap to the latest firmware and re-pair the hub. If you are using a Joule that hasn’t been updated, make sure you learn your G3 hub as an ANT+ device, not a power tap. See our video instructions for pairing with a Joule or pairing with a Joule GPS.

I lost/can't find my download cable, how can I download my Joule?

Any off the shelf mini USB stick to standard USB stick cable will work. If you own a Blackberry or digital camera you already have this download cable.

Why can't I download my Joule?

  • Make sure you have the latest version of PowerAgent
  • Make sure the download cable is plugged into your computer and Joule. You may want to try a different USB ports.
  • Make sure your Joule/Joule GPS/Joule GPS+ is turned on
  • Make sure you have “stopped and saved” a ride. To stop and save; hold the lower left minus button for 3 seconds until Ride Paused screen appears. Select “stop and save”.

How can I turn off my Joule?

Hold down the main front interval button and the “+” button together for 3 seconds.

What do VAM, Normalized Power, IF and TSS mean and what do I do with them?

VAM – How quickly the rider is climbing a hill. The rate of ascent in meters/hour. This feature is most effectively used in interval mode. Start an interval at the bottom of a large climb. Stop the interval at the top. See how quickly you’re gaining elevation.

Normalized Power (NP) – An estimate of the power the rider could have maintained for the same physiological “cost” if the output power was constant.

IF – Comparison (ratio) of a ride’s normalized power to the rider’s threshold value.

TSS – Training stress score: an estimation of a ride’s total difficultly based on glycogen burned.

For more definitions and information, visit our Glossary.

[Normalized Power, IF and TSS are registered trademarks of Peaksware, LLC http://www.trainingpeaks.com]

Why don't I see the ride information on the dashboard or in the reports after I stop and save?

The information is stored in the history files after a “stop and save.” History can be found under the cycling computer’s main menu, then navigate to History.

Why don't I see my current ride in the history files?

You need to stop and save the ride before the history file is created.

Note that the “end ride time” can be set to 90, 60, 30, 15 min or “never.” Default is “never.”

Temperature seems off on short rides.

The temperature sensor is embedded in the packaging and takes some time (30 min) to equilibrate. Short rides or quick temperature spikes may not register with the Joule.

Additionally, there is some self-heating from the electronics of when placed in direct sunlight.

Why is the "feet gained" different than a Garmin?

The Garmin uses a different altitude value based on both barometric pressure and GPS while the Joule uses just barometric pressure. Additionally, the Garmin and Joule use different averaging routines to calculate feet gained and lost.

Why is the data different between Garmin and PowerTap CPU?

Numerous differences exist between PowerTap and Garmin computers in regards to how data is displayed. To ensure minimal differences, you should verify the wheel circumference is correctly entered into both devices and that both devices handle ride stops, pauses, and resumption the same way. Garmin computers typically measure distance (and speed, depending on setup options) based on GPS data, and does not use the auto-pause feature by default. PowerTap computers measure speed based on wheel speed and distance based on the number of wheel rotations and uses an auto-pause by default. Garmin calculates average power output without zeros, while PowerTap does not by default, but there is a setting to change this (on both Garmin and PowerTap computers).

Directions on how to change settings on the Joule can be found in the product manual.

How is the PowerCal any different (why is it better) than a Heart Rate Monitor?

  • First, it introduces the relationship of a dose vs. training.
  • The PowerCal contains an algorithm that is sensitive to acute changes in Heart Rate (HR) and can account for rapid changes in power output.
  • It translates conversations into the vernacular of power training: watts, kilojoules, peak power, FTP, etc.
  • Current power meter users can now have uninterrupted training load data for activities where power meter data may be unavailable, like commuting or MTB riding.

Why does it no longer have to be calibrated?

After years of research and reevaluation of the algorithm it was determined that the calibration process added no more accuracy than the algorithm alone. Due to the variability of heart rate, both between and among individuals, calibration did not statistically increase accuracy of translated energy expenditure. Some individuals may see improved accuracy through calibration but, as a whole, the results show the algorithm alone is able to translate heart rate to power as well as individual calibration.

How accurate is it?

The PowerCal is not as accurate as a PowerTap and not intended to replace one. Research has shown varying degrees of accuracy based on individuals and types of riding. Accuracy will depend greatly on the individual and type of riding.

How does it compare to PowerTap?

It doesn’t and isn’t intended to. The PowerTap directly measures power through strain gauges on the torque tube, which is a direct measurement of power. PowerCal is an estimated value derived from HR.

How, after all these years of saying HR alone is not the best measurement for training, can you now measure power from HR?

There has always been a correlation between HR and power, it’s just that it varies depending on conditions. We’ve simply designed algorithms which predict power based on HR.

Will PowerCal give you both HR and power readings?

Yes. If pairing to a Joule, make sure to pair it was a heart rate monitor. The Joule will sense it as a PowerCal. If using a Garmin computer, you will want to be sure to pair the PowerCal as a powermeter and heart rate monitor.

How does it estimate KJ's burned: from HR or from estimated power?


How does it accommodate changes in fitness, fatigue, dehydration, etc. (all the things which influence HR)?

In terms of changing fitness with a given individual our initial assumption was that yes, as fitness increased the user would need to re-calibrate to properly adjust the system but what the research shows is that these changes are relatively very small compared to other factors at play when using heart rate as the base measurement. In other words, the margin of error when using heart rate as the sole measure of exercise intensity is too great to accurately represent changes in fitness.

In discussions of PowerCal as it relates to fitness, fatigue, dehydration, etc. one can look at the power output relative to other metrics such as speed over the same course or changes in cadence over time. Power output as a performance metric is almost always spoken of in terms of how it relates to the other variables to gain insight to the individual’s progress.

Is it more accurate for certain types of riding (steady-state intervals, climbing, sprinting, etc.)?

PowerCal is more predictable in a steady-state, longer intervals or climbing where constant fluctuations in output are minimized.

Why does the power reading jump around so much?

This is a question we get with new PowerTap users as well. The answer is the products are able to measure very small changes. In the case of the PowerTap (hub) it can measure changes in torque and velocity very rapidly. Even experienced cyclists do not have ability to put the exact same force with each leg on every pedal stroke- the result is a power reading that jumps around a lot. As cyclists improve their pedaling smoothness the power numbers fluctuate less, but the fluctuations will always exist.

For PowerCal the situation is very similar- your HR is constantly changing even though your BPM does not reflect these changes. The PowerCal picks up on even the most minute change in the time between heart beats and the result is a spike in power from a rapid change in HR, much like the PowerTap shows a rapid change in torque or velocity. The PowerCal’s ability to measure and quantify these changes is what makes it such a great product and gives the user a much better experience and a more accurate measure of total work than HR alone.

Will my phone or tablet work with the BLE Powercal?

The BLE powercal will work with iphones versions 4S, 5, 5S, or 5C as they have Bluetooth 4.0 integrated. With tablets you must have an ipad 3 or higher, and Android tablets must have Jelly Bean OS 4.3 or higher.

View more information about which products are compatible with Bluetooth Smart.

Is the C1 a complete crank set up or just the chainrings?

The C1 is a 1 piece design which include a 1 piece large and small chainring , sensor and electronics. Crank arms is not included. The C1 bolts to your existing 110 BCD crank spider. Check the C1 crank compatibility chart for specific fitment.

Our chainrings are not compatible with anything less than 50-36 due to sensor and gearing interference.

Will the C1 need to be calibrated?

No, the C1 chainrings are calibrated at PowerTap. Specific and even torque must be applied to each of the bolts connecting the chainring and the sensor. Torque specifications will be published at release.

Can I manually zero or auto zero the C1 chainrings?

Yes, just like the PowerTap hub, you can perform a manual zero. We recommend that you perform a manual zero before each ride. The C1 also has auto-zero that is triggered while coasting during your ride.

Will the C1 chainrings work with my carbon cranks?

Yes, the C1 chainrings work with most alloy and carbon cranks with 110 BCD, 5 bolt pattern compatibility. Check the C1 crank compatibility chart for specific fitment.

Can I replace the chainrings if they get worn?

Chainrings can be replaced by user if replacing with same tooth profile. We recommend that chainring repair be done by PowerTap for recalibration purposes. If a different tooth configuration is desired we require the sensor to be recalibrated by PowerTap.

Will the C1 work with a 130 BCD crank?

The C1 is designed for only 110 BCD, 5 bolt pattern cranks.

Can the C1 be installed on a 4 bolt pattern crank spider?

The C1 is designed for only 110 BCD, 5 bolt pattern cranks.

What type of battery does the C1 need?

The C1 uses a replaceable coin cell CR2032 battery.

What is the warranty on the C1 chainrings?

The electronics have a 2 year global warranty. The chainrings are a wearable item and do not have a warranty.

Will the P1 need to be calibrated?

There is no extra needed calibration when installed.

How much torque do I need to use when installing the P1 pedals?

We recommend you follow the recommended torque guidelines from your crank manufacturer. Pedal installation torque generally ranges from 300-350 in lbs (35-40 Newton-meters).

What size Hex wrench is needed to install the P1?

You will need an 8mm hex wrench.

Do I have to set the installation angle on the P1?

No, you do not need to set the installation on the P1 pedals. The P1 pedals learn the position of the axle relative to the crank arm after a few pedal strokes.

Can I manually zero or auto zero the P1 pedals?

Yes, just like the PowerTap hub, you can perform a manual zero. We recommend that you perform a manual zero before each ride. The pedals also have active temperature compensation where sensors within the pedal monitor the temperature and adjust the offset accordingly.

What do I do if my P1 pedals go out of calibration?

First, perform a manual zero and LEDs for indication of potential error. For a full list of LED functionality consult the P1 user guide. If that does not fix the issue, or you see an LED indicating a failure, please call our customer service team to receive a Return Authorization number to send your pedals back to Saris Cycling Group. You will need to send back both pedals.

Are the pedals single or dual sided?

The P1 pedals are two separate power meters, which talk to each other. The data is collected by the master pedal (Left), then sent to your head unit. The P1 pedals allow the user to receive detailed left/right leg balance.

Will you be offering a single sided only pedal?

Not at this time.

What type of cleats do the P1 pedals use?

The P1 pedals use proprietary, 3-bolt keo-style cleats. 0 degree and 6 degree float options are available.

What type of battery does the P1 need?

Each pedal uses one AAA battery. Two AAA lithium batteries are included with the P1 pedals. For best performance we recommend using lithium batteries.

Can I adjust the release tension on the pedal?

Yes, you will need a 2.5mm hex wrench to adjust. Release tension range is 6 – 20 Nm.

Does the P1 come with cleats?

Yes, the P1 come with proprietary 6 degree float PowerTap cleats and hardware. We offer a 0 degree float cleat option as an extra accessory.

Do the P1 pedals have a weight limit?

No weight limit.

What is the warranty on the P1 pedals?

The electronics have a 2 year global warranty. The bearings, skid, and plate are all wearable items and do not have a warranty.

Will the P1 be user-serviceable?

Serviceability will be limited to external wear items like the claw, spring, pedal plate and battery cover o-ring. All other internal wear components must be serviced at PowerTap.

Will I still receive a power reading if one pedal loses battery power before the other?

When battery life reaches 20%, the P1s will send a low battery flag to your head unit, which should help prevent complete loss of battery by warning you ahead of time. If the right pedal battery dies, the left pedal will double its output to create a power reading. If the left battery dies, there will be no power reading.