Power Meter options for MTB

[trailgumby]

I have a Quarq PM on some X0 carbon cranks. Apart from my missing the 24T granny ring (minimum 26T on the PM - I have steep terrain in my area) it has been flawless.

How do I find using a PM on the MTB? I doubt I'd do it again.

I bought it because I had a concern about overtraining after having almost every race I intended entering interrupted with illness last winter. Being more disciplined with internet use and getting more sleep this season has helped a lot so far.

I find the TSS (TrainingPeaks) is understated compared to road by 20% or more, because MTB uses so much more upper body and core compared to road for the same effort. Whereas if I use HR TSS it seems about right.

I never get to watch the numbers on the MTB - trying to do so is a recipe for crash and injury. It's only any good for post-ride analysis, and is limited by the issues mentioned above. Save your money and get some coaching instead.

On the road bike, yes PMs are very useful for training. I have one of the new model P2Ms on some Rotor cranks with non-Q-ring chainrings, and it just works. Particularly good for short HIT intervals, much better than using HR.

[Jaker]

Does anyone know why the Stages power meters can't seem to be used on a carbon crank? Does it have something to do with how rigid carbon is? Are these things measuring strain in the crank arm?

[kophinos]

they measure deflection of the crank arm.

Does anyone know why the Stages power meters can't seem to be used on a carbon crank? Does it have something to do with how rigid carbon is? Are these things measuring strain in the crank arm?

[aaric]

Carbon doesn't react to force as predictably as aluminum does. Additionally, the bonding surfaces tend to be less flat

It's likely possibly to do, but making it a product is much more difficult given stages and 4iiii's inability to support carbon cranks initially.

[Jaker]

I would think it'd be a simple as installing the power meter, setting it up in their calibration rig, applying a known force to the arm and setting the meter/strain gauge appropriately. Then again, I'm not 100% sure of their methods.

[kophinos]

Carbon doesn't react to force as predictably as aluminum does.

[Geoff]

That is essentially correct. To get around that, manufacturers mount carbon arms to an alloy powermeter chassis, which works fine. I love my SRM and have had good results with it, though I know some have had issues with the MTB versions. I am still running an older wired version, which has been really reliable.

[borinomi]

I recommend stages power meter.

[MikeMoore]

I've also had no issues with my Xt Stages, bar a couple of battery changes.

[Vallinotti]

Hi all,

I'm looking for a powermeter for my new Trek Top Fuel 9.9SL. However this boost 148 standard is problem in selecting a crank based powermeter for a 1x11 drivetrain(XX1) it should have a chainline of 52mm but this information is not open wide in the Internet . Could someone which have a pm with gxp or 24mm spindle with Q factor larger than 160mm inform me the chainline measurement of your PM?

[Jaker]

I still think if you calibrate your testing rig with a known accurate aluminum crank arm setup, and then throw a carbon arm into the machine and measure the "output", you could easliy calibrate these things to a carbon crnak arm. Then again, I'm not an engineer.

[jimborello]

I had a Stages on my mtb and sold it after half a year. It worked well but it took away the joy of riding my mtb. IMO power is for the road unless you only ride mtb