Crank powermeter for a fat bike, (single chain ring)

[cetuximab]

I want to build a full susp fat bike.

The frame I am looking at requires 120mm BSA crank.

Never had a powermeter. I just downloaded training with a powermeter.

The powertap is only available with a 160mm rotor, so I decided against their hub powermeter.

So, thinking about a crank located powermeter. I like my single chain ring bikes. I have 1x10 and a 1x11 that work flawlessly.

Any recomendation?

Thanks

[loxx0050]

Pedal based? Powertap P1 or Garmin Vector...there is another I believe but the name escapes me at the moment. Both offer single sided versions if you are on a budget.

[djg21]

Pedal based? Powertap P1 or Garmin Vector...there is another I believe but the name escapes me at the moment. Both offer single sided versions if you are on a budget.

On a fat bike? To be ridden on trails? I don’t think anyone makes a pedal-based power meter for an MTB. There are some crank options, but they are expensive. If you get a Powertap G3 hub, can’t you switch the rotor?

https://powermetercity.com/2016/12/31/mountain-bike-power-meters/

https://shop.brake-stuff.de/en/powertap/172-140mm-disc-rotor-for-powertap-hubs.html

[zank]

I think your only option is the Stages Carbon GXP for MTB arm. Stages doesn't make a long enough spindle for their BB30 SRAM mtb arm.

[thegunner]

I think your only option is the Stages Carbon GXP for MTB arm. Stages doesn't make a long enough spindle for their BB30 SRAM mtb arm.

or just get a quarq and run a single chainring.

[zank]

How though with a 120 mm BB shell?

[shovelhd]

What's wrong with a 160mm rotor? You can't change the bracket?

[zank]

Can a PT be fitted to a 177 or 197 rear end of a fat bike?

[SkyRider]

Stages is a strong option but they do have a number of transmission issues. Depending on your timeline Raceface will have a cinch spindle power meter for fat bike soon and it can be paired with any of their arms and and cinch direct mount chainrings. Quarq could be an option but it’s not a stock setup. You would need to order the power spider separate from the direct mount crank and install it. That will put a limit on the smallest chainring you can run. Stay away from pedal based power as a rule (as far as I know they are road only still but this is a general statement). They are heavy, have a tall stack height and are unreliable generally suffering from very specific install requirements that can wildly alter the reading accuracy.


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[SkyRider]

Can a PT be fitted to a 177 or 197 rear end of a fat bike?



To my knowledge PowerTap doesn’t make a 177 or 197 hub and their hub would not be adaptable to those standards.


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[SkyRider]

Question for the OP. What frame are you using? A bit more information on the frame and therefore the standards involved might help to get you a better answer.


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[cetuximab]

What's wrong with a 160mm rotor? You can't change the bracket?

The bike comes with a 160 mm rotor bracket.

I weight 205. The last few bikes I built had 205 front and 180mm rear disc rotors. This full susp fat bike is to ride in our local trails. (many are quite steep and tech). And the occasional trip to moab.

[cetuximab]

Question for the OP. What frame are you using? A bit more information on the frame and therefore the standards involved might help to get you a better answer.

Generic Chinese Carbon Frame

It will fit 4.6 wide tires.

[chiasticon]

I'd like to hear more about your experience with using the power meter on the fat bike, once you get one. to me, it wouldn't be an ideal situation to train specific zones and weaknesses. but I think a lot of that depends on what sort of terrain you're riding as well. for example: snowy, technical singletrack versus beautifully-groomed cross-country ski trails.

[Mzilliox]

The Easton/Race Face Cinch system has a spindle based PM. I just picked one up for an Easton Road and gravel crank, but have not used it at all yet.

[loxx0050]

On a fat bike? To be ridden on trails? I don’t think anyone makes a pedal-based power meter for an MTB. There are some crank options, but they are expensive. If you get a Powertap G3 hub, can’t you switch the rotor?

https://powermetercity.com/2016/12/31/mountain-bike-power-meters/

https://shop.brake-stuff.de/en/powertap/172-140mm-disc-rotor-for-powertap-hubs.html

Didn't say it was a good option just what I could quickly think of off the top of my head with that interesting crank/BB option.

I just thought of the Rotor inPower with a MTB spider but not sure it will fit the BB on that fat bike since those are 30mm spindles...plus that width not sure there are enough spacers that Rotor provides that will work either.

[Mikej]

Be sure to check for clearance if you go stages- fat bikes can be pretty tight space wise. I wonder out loud if the lower pressures will cause problems?

[SkyRider]

I did some checking today. At present the only option is a stages. Raceface should have an option shortly but I don't believe that spacing is available just yet.

Like I said above, The stages units I have worked with arr less then ideal. they suffer from a host of reliability issues but it's the only game in to at the moment.

hope this helps

[cetuximab]

Pedal based? Powertap P1 or Garmin Vector...there is another I believe but the name escapes me at the moment. Both offer single sided versions if you are on a budget.

Thanks for the response, but the P1 and Vector are both road pedals.

Besides i worry about reliability of a pedal based powermeter with pedal strikes. In the tech sections...it happens not uncommonly.

[cetuximab]

https://shop.brake-stuff.de/en/powertap/172-140mm-disc-rotor-for-powertap-hubs.html


Not in stock. I contacted them a couple weeks ago. I asked them when they will make more and no response.

[cetuximab]

I think your only option is the Stages Carbon GXP for MTB arm. Stages doesn't make a long enough spindle for their BB30 SRAM mtb arm.

Stages confirmed

"The meter that we have had the best luck with for a fat bike application is using a SRAM GXP crankset paired with a Stages Carbon for MTB GXP. The one caveat to this is insuring that there is ample clearance between the left crank arm and the frame. We suggest a minimum of 10mm between the crank arm and chain stay."

[cetuximab]

The Easton/Race Face Cinch system has a spindle based PM. I just picked one up for an Easton Road and gravel crank, but have not used it at all yet.

From Easton

"No we only have the 2 spindle lengths: 134 for MTB and the 129 for Road."