Like many, I have an older road bike on the trainer with a well worn drive train. Over the past couple of weeks, the front derailleur broke (no problem, found one on the 'bay for 20 bucks) and on the very next session, the rear shifter gave up the ghost. I’m not too keen on dumping good money after…

[image] johnnyseven: Or would there be no real difference. YES, there will be a very real difference. Crank length is a key factor in power calculations for pedal PM’s. [image] johnnyseven: how would this effect the readings. Previously would the readings have skewed higher or lower th…

Power readings should now be lower with the crank length and settings properly aligned, I believe. If you’d been running 175s, the opposite would be true.

Power = Torque * rotational speed Torque = Force (what the power meter measures) * distance (crank length) Power = Pedal force * crank length * rotational speed So since you lied to the power meter and told it to use a longer crank length than actual in the power equation, it was inflating your p…

I just did this on accident when I took the pedals off one bike and then put them on another bike that had cranks that were 10 mm shorter. My power readings were significantly higher until I realized that I needed to change the setting on my head unit. Once I made the change it was reading back to n…

[image] huges84: One important caveat: Assiomas use the crank length set in the recording device (Garmin, Trainer Road, etc) as the crank length. Whatever you set in the Assioma app will be ignored on other devices / apps. is there any source for this? I got the same problem and would like to…

IIRC, it’s because it’s part of the ANT protocol that requires (or at least allows) the recording device (Garmin, Wahoo, app) to specify the crank length. So each device you record with may change the crank length to override whatever you set in the Assioma app. Regardless, the Assioma user manual …

Thanks a lot for the reply. I looked into the TrainerRoad android app and cannot find the setting for the crank length. Is it because I use the Bluetooth connection and so it takes the value from the app?

[image] huges84: Assioma user manua Is that peculiar only to Assioma? I have Powertap and keep forgetting which bike has which crank length…

I’m not sure, but I think it applies to all power meter pedals

TrainerRoad

Crank length vs power

Equipment

ddddavidee April 4, 2024, 10:48am 7

is there any source for this? I got the same problem and would like to understand if my readings were correct or not.

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Crank length vs power

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