Ok power meter nerds, help me mount a meter on a fatbike!

[bigdirt]

Living in a cold climate has got me riding outside as much as possible. I would love to mount a power meter on my fatbike(snow bike with 26x5.0” tires for those who are not familiar). I have been unable find a power meter that will work on this bike. It uses a Sram Stylo Fat 4 crankset. Normally a spider based power meter would work from someone like Power2Max would work but the chainring offset is -4mm where a standard boost chainring offset it +3mm. A crank arm based meter will not fit due to chain stay clearance. I am open to swapping to a new set of cranks

The Stylo DUB cranks have a Q factor of 196mm with a 100mm treaded BB and a chain line of 58mm.

Call me crazy for adding a power meter to a fatbike bit I ride this thing 4-8 hours a week and it incorporate some outdoor workouts.

Any ideas on a solution?

Thanks!

[liam_mail]

Your best bet is the Xpedo Assioma hack isn’t it? I have seen it pop up here quite a few times and it looks like a good setup.

[Dave]

They will be expensive but the new SRM PM Pedal could be an option…depending on reviews from the likes of DC Rainmaker.

[kevstraining]

I was going to suggest the assioma hack too

Favero assioma plus xpedo SPD pedal bodies…

A Wild idea for Favero Assioma pedals [MTB SPD Hack]

This week Favero released version 4.04 and new pedal bodies. When I saw the pedal bodies I thought of an idea. Why not 3d print bodies which can fit on the pods of Favero Assioma’s with Shimano SPD double-sided clipless mechanism? Example: I and other people want powermeter pedals for road as well as MTB riding. This would be a nice solution. Are there people with expertise in 3d printing or pedals based powermeters who think this is possible? Or impossible (please give a reason why)

[bobw]

4iiii do (or did) a service where they’d fit one of their systems to your own cranks. Not sure if it was just the road oriented models (105, Ultegra, Dura Ace, etc.) or if they can fit any crank. From memory I think it was only solid cranks so hollow carbon fibre models wouldn’t work.

No harm in asking.

[Bhofstra]

Have you tried emailing Power2max and explaining what you have, they’re really good about working with you to find the right fit for your bike. I have a Power2max on my Beargrease with a Sram GXP crank and it works perfectly. I’ve also run a 1x Srm on the bike before too

[mcneese.chad]

He already mentioned that crank arm to chainstay clearance would be and issue preventing use of a crank based power meter. Stock or factory retro-fit won’t make a difference because the arm power pod is too big in any case.

[bobw]

Oops! Missed that bit

[firemunki]

Might be harder to find but powertap did make a MTB version.

Although I think p2m discussions might be best.

[mcneese.chad]

@firemunki

powertap did make a MTB version.

That was only a 148mm wide axle, and fat bikes are well beyond that at 170mm for most modern bikes, so no way that works either.

[bigdirt]

Thanks for all the help team. I have talked to Power2max was helpful but do not really have any options. I have reached out to SRM but don’t want to drop that kind of coin!

The only crank arm style meter that has a option for SRAM fat bike cranks is 4iiii. They say they would like a AAA battery worth of clearance between the arm and chain stay. I am about 90% there with the BB spaced over. Maybe 1mm shy. This fat bike should be more stout than the average road frame so hopefully it would not flex enough to contact the frame. I think this is my best option!

[Bhofstra]

You’ll be very happy once you have power on your fatbike. I like doing my workouts on the fat bike instead of inside, and race and general riding data is very interesting to look at after too

[Max_Matheson]

Right on, I’ve considered doing this sort of thing too, but currently putting. my money into a smart trainer (fatty can wait). I would be curious about temps and temp fluctuations, and if those would mess with your power data or the unit itself? If you stored inside and had a big T swing just taking the bike out, would that cause issues with the meter in terms of function/longevity?

[logella]

As others have mentioned the Assioma hack is your answer. It works brilliantly. I have it on my gravel bike and love it.

[Bhofstra]

I haven’t had any issues with temps or conditions affecting my powermeters, even when the bottom bracket area is packed with slush or snow they still work just fine.
I had my SRM for 4 winters of use with no corrosion or other issues, This will be my 3nd winter on my Power2max and it still looks new after last winter

[Dave]

Most modern PM’s have temperature compensation built in so that shouldn’t be an issue. However, if there’s a big swing like you describe then it might be worth leaving the bike outside (if you can) for 5 min before riding.

[Max_Matheson]

I’ve seen the claims for temp compensation or just function, with Assioma claiming that the Faveros are good from -10 C (14 F) to + 60 C (140 F). That range should be fine for most people, but here in MN we regularly get down significantly below the -10 C / 14 F mark and so I’d be curious about their longevity in that sort of climate.

What are typical winters like for you, @bigdirt and @Bhofstra? Also, thoughts about salt/slush corrosion for a PM on a winter fatbike?

[Bhofstra]

I’m in Michigan and ride from home, so typical temp range is 15-35°F with lots of slush in the bike. I used my SRM at -20 one day and have gone down to 0 with my Power2max, no issues with either at cold temps, my Garmin is the one that I have troubles with since the battery on that drains so fast, but powermeter accuracy and batteries have been fine. I’ve had zero corrosion issues

[bigdirt]

I ride down to about 0F from time to time but really anything below 10-15F is not as much fun. lol!

I ran a 27.5" Plus studded tire on a hardtail last winter with a Raceface(Easton) power meter spindle. It worked flawlessly every time I took it out in the cold!

[sicolangelo]

I’m struggling with a similar issue. I have SRAM SX EAGLE DUB FAT5 cranks with a 30T stamped with 4mm offset, not the -4mm the OP mentions. I’m not expert in Boost or offsets but the Power2Max guys tell me their Boost option should work ok for me given the minimal diff. Still not an option though as their smallest chainring right now is a 32 and I dare not drop below a 30. They did say they are expecting in a 30T chainring soon though. Interested in any feedback. For what it’s worth, I did try a Powerpod last winter. I’ve had LOTS of really good experience on a couple of bikes , in particular one I use exclusively for hill climbs - but not so much on the snow. The Velecomp guys do offer a “profile” - config file you can use on their forum but it just didn’t work well for me.