Several weeks ago I posted instructions for mechanically calibrating your KICKR to your external power meter once and for all—no firmware or software updates required. I wanted to update that post at this time to state that this solution continues to work extremely well for me. My Kickr's power is well within a 2% margin from both my SRM and Stages power meters. Very little additional tweaking of the belt tension has been required.
To be clear, when doing a TrainerRoad workout, I deselect "use power from electronic trainer." The workout then records/displays the power from my external power meter (I mostly use my bike with the SRM) and with this setup, my Kickr is controlled very precisely to achieve the correct power.
So, at the risk of being reprimanded for repeating my post, I'm including the original instructions below. It's important to follow all the instructions carefully and in the correct order. Do not do another spindown for your Kickr after completing these instructions. If you need to tweak your calibration, simply turn the tension screw a tiny amount in the appropriate direction.
A lot of you are struggling with Kickrs that read +25-30 watts as I once was. Based on my experience I think you'll be very happy with the results. If, and when Wahoo comes out with software fix that gets integrated into TrainerRoad, your Kickr will still work with the new software after this calibration process. That may not be available until next winter season, though, so I think going this route at this time makes sense even with a potential software solution on the horizon.
Also, some of you have mentioned that you've been able to set your Kickrs to permanently follow your external power meters using the beta firmware without having to relaunch the Wahooligan app. This is contrary to how Wahoo has stated the functionality works. Therfore I'm not certain this is technically possible and I can't help but question whether or not you're really seeing what you think you're seeing.
At any rate... Original instructions (with minor clarification updates):
While we wait for the official software release from Kickr that will allow control from an external power meter (and developers to implement the SDK) I have a working fix for inaccurate Kickrs.
I've had my original Kickr replaced, purchased the calibration kit, done countless spindowns both cold and warmed-up and no matter what, my Kickr reads about 20 watts higher than reported from both my SRM and Stages power meters.
I've noticed that the discrepancy can be lessened by pedaling through the spindown to make it artificially longer, or by adding to the weight when using the calibration kit and app. Neither method has led to a reliable and accurate solution, but it did show me that there are ways to unofficially manipulate the Kickr to get it behave a bit better. In fact, it seemed obvious that either a mechanical or software based calibration dial could have been implemented by Wahoo to allow us to adjust the Kickr's wattage to match an external meter. If the Kickr consistenty reads 20 watts high, just turn the dial until it reads correctly. Why didn't Wahoo just give us something like this?!
Well, it turns out they did. It is possible to adjust the belt tension on your Kickr and that, in turn, will adjust a Kickr's reported wattage. Now, this is not how Wahoo intended us to use the belt tension adjustment and this is a workaround they probably wouldn't officially recommend. But if you've been struggling with this as much as I have and want a real solution to the problem, follow these instructions:
FOR A KICKR THAT REPORTS WATTAGE THAT IS TOO HIGH:
First, locate and familiarize yourself with the access hole for the belt tension adjustment screw. It is located on the rear of the Kickr on the plastic casing just above the top of the handle. If you have trouble locating the hole or understanding where the adjustment screw is, you can remove the plastic casing from the drive side of the Kickr. There are two hex bolts and one tiny Phillips screw that need to be removed.
Removing the cover isn't absolutely necessary, though, as you can access the adjustment screw through the access hole. Use a 2.5 mm hex driver. If you don't remove the cover, you might have to adjust the position of the hex driver to find the screw head. Try pointing a bit down if you keep missing it.
Once you find the adjustment screw and are comfortable with adjusting it, warm up your Kickr for 10-15 minutes and then do a spindown calibration. For our purposes, you want the spindown to be about 23-24 seconds (normally, without using this procedure you'd want it at about 15 seconds, but we'll get there). If it is shorter than this, turn the belt tension screw counter-clockwise. This will loosen the belt tension and allow the spindown to take more time. Keep adjusting the screw and performing spindowns until you get a number in the 23-24 second range. The reason you're doing this is that after you get your spindown in this range, you're going to tighten the tension. You don't want your tension too tight, so if you start in this range you'll most likely end up with a good result.
Once you've gotten your spindown in the 23-24 second range, say goodbye to future spindowns. This should be the last one you do from this point on and you will calibrate your Kickr to your power meter solely using the belt tension screw. If you do another spindown after the following calibration steps, you will bring your Kickr back to reading too high.
Next, use Trainer Road, the Wahoo app or whatever you're comfortable with to give you a steady wattage to help you calibrate. Choose a wattage that's not too easy, but something you can hold. Endurance to tempo pace is good.
Also, make sure your trusted power meter is functioning, zeroed-out and you have a way to read its output. You can do this with TrainerRoad or using a Garmin. In TrainerRoad, make sure your power meter is connected and DESELECT "use power from an electronic trainer" to display power from your trusted external power meter and not the Kickr.
Start riding at a steady 90 cadence and note the difference from your Kickr's target power and your trusted power meter's actual power. If the Kickr is reading high, get off the bike and turn the tension screw clockwise a couple of turns. Get back on the bike and you should now notice that your power meter is reading higher at the same target power. Your're working harder now, but the target power is same. Keep up with this adjustment process until the average power from your power meter matches the Kickr's target power. Note that the power will go up and down a bit (+/- 5 watts or so) as the Kickr cycles to maintain the target power, but once the average is about the same, your Kickr is now calibrated to your power meter.
At this point, make sure that your Kickr has not become louder or "screeechier" than before. This would indicate that the belt tension is too high. If so, start the process over again with your final spindown at a looser belt tension than what you started with for. Remember, once you have a calibration you are happy with, DO NOT ever do another spindown. Any future calibrations should be done only using the belt tension screw.
I haven't heard many reports of Kickrs reporting wattages that are too low, but the same process could be used to correct those errors. In that case, you'd want to start at a higher belt tension as calibration will require reducing tension after the final spindown.
To be clear, when doing a TrainerRoad workout, I deselect "use power from electronic trainer." The workout then records/displays the power from my external power meter (I mostly use my bike with the SRM) and with this setup, my Kickr is controlled very precisely to achieve the correct power.
So, at the risk of being reprimanded for repeating my post, I'm including the original instructions below. It's important to follow all the instructions carefully and in the correct order. Do not do another spindown for your Kickr after completing these instructions. If you need to tweak your calibration, simply turn the tension screw a tiny amount in the appropriate direction.
A lot of you are struggling with Kickrs that read +25-30 watts as I once was. Based on my experience I think you'll be very happy with the results. If, and when Wahoo comes out with software fix that gets integrated into TrainerRoad, your Kickr will still work with the new software after this calibration process. That may not be available until next winter season, though, so I think going this route at this time makes sense even with a potential software solution on the horizon.
Also, some of you have mentioned that you've been able to set your Kickrs to permanently follow your external power meters using the beta firmware without having to relaunch the Wahooligan app. This is contrary to how Wahoo has stated the functionality works. Therfore I'm not certain this is technically possible and I can't help but question whether or not you're really seeing what you think you're seeing.
At any rate... Original instructions (with minor clarification updates):
While we wait for the official software release from Kickr that will allow control from an external power meter (and developers to implement the SDK) I have a working fix for inaccurate Kickrs.
I've had my original Kickr replaced, purchased the calibration kit, done countless spindowns both cold and warmed-up and no matter what, my Kickr reads about 20 watts higher than reported from both my SRM and Stages power meters.
I've noticed that the discrepancy can be lessened by pedaling through the spindown to make it artificially longer, or by adding to the weight when using the calibration kit and app. Neither method has led to a reliable and accurate solution, but it did show me that there are ways to unofficially manipulate the Kickr to get it behave a bit better. In fact, it seemed obvious that either a mechanical or software based calibration dial could have been implemented by Wahoo to allow us to adjust the Kickr's wattage to match an external meter. If the Kickr consistenty reads 20 watts high, just turn the dial until it reads correctly. Why didn't Wahoo just give us something like this?!
Well, it turns out they did. It is possible to adjust the belt tension on your Kickr and that, in turn, will adjust a Kickr's reported wattage. Now, this is not how Wahoo intended us to use the belt tension adjustment and this is a workaround they probably wouldn't officially recommend. But if you've been struggling with this as much as I have and want a real solution to the problem, follow these instructions:
FOR A KICKR THAT REPORTS WATTAGE THAT IS TOO HIGH:
First, locate and familiarize yourself with the access hole for the belt tension adjustment screw. It is located on the rear of the Kickr on the plastic casing just above the top of the handle. If you have trouble locating the hole or understanding where the adjustment screw is, you can remove the plastic casing from the drive side of the Kickr. There are two hex bolts and one tiny Phillips screw that need to be removed.
Removing the cover isn't absolutely necessary, though, as you can access the adjustment screw through the access hole. Use a 2.5 mm hex driver. If you don't remove the cover, you might have to adjust the position of the hex driver to find the screw head. Try pointing a bit down if you keep missing it.
Once you find the adjustment screw and are comfortable with adjusting it, warm up your Kickr for 10-15 minutes and then do a spindown calibration. For our purposes, you want the spindown to be about 23-24 seconds (normally, without using this procedure you'd want it at about 15 seconds, but we'll get there). If it is shorter than this, turn the belt tension screw counter-clockwise. This will loosen the belt tension and allow the spindown to take more time. Keep adjusting the screw and performing spindowns until you get a number in the 23-24 second range. The reason you're doing this is that after you get your spindown in this range, you're going to tighten the tension. You don't want your tension too tight, so if you start in this range you'll most likely end up with a good result.
Once you've gotten your spindown in the 23-24 second range, say goodbye to future spindowns. This should be the last one you do from this point on and you will calibrate your Kickr to your power meter solely using the belt tension screw. If you do another spindown after the following calibration steps, you will bring your Kickr back to reading too high.
Next, use Trainer Road, the Wahoo app or whatever you're comfortable with to give you a steady wattage to help you calibrate. Choose a wattage that's not too easy, but something you can hold. Endurance to tempo pace is good.
Also, make sure your trusted power meter is functioning, zeroed-out and you have a way to read its output. You can do this with TrainerRoad or using a Garmin. In TrainerRoad, make sure your power meter is connected and DESELECT "use power from an electronic trainer" to display power from your trusted external power meter and not the Kickr.
Start riding at a steady 90 cadence and note the difference from your Kickr's target power and your trusted power meter's actual power. If the Kickr is reading high, get off the bike and turn the tension screw clockwise a couple of turns. Get back on the bike and you should now notice that your power meter is reading higher at the same target power. Your're working harder now, but the target power is same. Keep up with this adjustment process until the average power from your power meter matches the Kickr's target power. Note that the power will go up and down a bit (+/- 5 watts or so) as the Kickr cycles to maintain the target power, but once the average is about the same, your Kickr is now calibrated to your power meter.
At this point, make sure that your Kickr has not become louder or "screeechier" than before. This would indicate that the belt tension is too high. If so, start the process over again with your final spindown at a looser belt tension than what you started with for. Remember, once you have a calibration you are happy with, DO NOT ever do another spindown. Any future calibrations should be done only using the belt tension screw.
I haven't heard many reports of Kickrs reporting wattages that are too low, but the same process could be used to correct those errors. In that case, you'd want to start at a higher belt tension as calibration will require reducing tension after the final spindown.
Last edited by:
Krispy2014: Feb 15, 15 22:45