Hack!? Shimano XT Crank on a Fatbike

Photo by Diglloyd

Recently, we got a tip informing us that someone had seen a Moots FrosTi out there with a Shimano XT crankset. They had sent some pictures, but with zero information and pictures that really didn’t prove it was a 100mm BB we had little to go on. It didn’t take us long though to stumble on Lloyd Chamber’s cycling blog, that happened to have a gallery of photos of a Moots FrosTi with an XT crank. It just so happens that not only is Lloyd an amazing photographer, he is also quite the cyclist with his fleet of Moots being some of his favorite subject matter among other cycling related photos. There it was, clear as day – a Shimano M780 crankset on a Moots FrosTi.

How did he do it? Find out after the break.

Hack!? Shimano XT Crank on a Fatbike

Photo by Diglloyd

This puzzle was on my mind this past weekend while down at CX Worlds, so I asked around at the Shimano tent if they knew of any way this was possible, or if they were dabbling in fatbike cranks. Not only did they not think it was possible, but even more disappointing they didn’t think Shimano would get around to making a fatbike crank soon – or, if ever. The market is simply too small apparently. It’s not a matter of “if” Shimano could make a fatbike crank, it’s more if they did, how many would they sell? I quickly forgot about the fatbike issues with the roar of the cyclocross crowd.

Hack!? Shimano XT Crank on a Fatbike

Photo by Diglloyd

That is, until I spoke to Lloyd. I had been told by a friend in the know that since the spindle is simply pressed into the crank arm, it might be possible to press it out and have a longer one pressed in. After asking Lloyd about it, the answer I got was “special project for the crank.”


Prying a little farther, it turns out Lloyd was simply being conscious of his connections and was being careful about what he said. Finally, he came back and said that the crank modification was a custom job he had made to his specs by a member of the Shimano staff who prefers to remain anonymous. So there you have it. Possibly one of the only, or very very few XT fatbike cranks on the market with no plans for production. Still cool none the less.

Thanks to Lloyd for sharing his photos and his FrosTi with us!


truman - 02/07/13 - 10:19am

Man it helps to know people!

Roy - 02/07/13 - 10:31am

If you are the kind of guy that has a Moots fat bike, then you are the kind of guy that would pay anything for a custom crank setup…or potentially have the connections to get one made…

isaac - 02/07/13 - 10:40am

Since Sram has an X9 and X5 fatbike crank coming out this year ,plus 4 fatbike offerings from race face, shimano can suck my knards

Kovas - 02/07/13 - 10:47am

We do a similar mod on SRAM and Shimano cranks to fit our 100mm shells. Our spindle-mod only ads a few grams, but works as good as factory fresh… Fat is where it’s at!

The Dude - 02/07/13 - 11:27am

Can’t wait for fatbike trends to die hard in a year and people having 100mm shells with cranks good on nothing else. Worst bikes ever.

pablo - 02/07/13 - 11:28am

isaac: Funny, all the brands you mentioned have no endplay adjustment. It still baffles me that mfgs continue down that path.

Ben - 02/07/13 - 11:34am

@The Dude as a tried and true roadie who was absolutely sure I would never have fun off road, I think you are completely wrong. If you honestly believe they are the worst bikes ever it would seem to me you have never ridden one. Haven’t spoken to one person who hasn’t loved it the moment they stepped on one

mrcykel - 02/07/13 - 11:36am

The Dude —–> Haters Gonna Hate

Mindless - 02/07/13 - 11:43am

If they come out with 100mm SLX they will own the market.

Mindless - 02/07/13 - 11:43am

@Dude is an idiot and lives where there is no snow.

Mindless - 02/07/13 - 11:45am

@pablo: exactly. SRAM and RaceFace still can’t figure out how to attach their cranks properly.

bin judgin - 02/07/13 - 11:47am

sram and raceface can’t attach their cranks? what???

King County - 02/07/13 - 11:52am

I have never ridden a fat bike, but love the concept.

A few questions for those with experience: If there is 2 feet of fresh / untouched snow, can a fat bike make it through? How is a fat bike on dry, loose beach sand? Thanks

Champs - 02/07/13 - 12:10pm

… why not XTR?

Pete - 02/07/13 - 12:20pm

Champs got it right. Why go through all that trouble and not use an XTR? Does Shimano use a different manufacturing process that would have made it impossible?

Mindless - 02/07/13 - 12:31pm

XTR has lower Q factor – maybe it would not clear chainstays? It could be a different press fit too..

biassuit - 02/07/13 - 12:37pm

@King County – My experience is that 2 feet of fresh powder is as unrideable on a fatbike as it would be on a road bike. You would need 12 inch wide tires and a rider weight of 20 lbs to get enough float. On less powder and/or packed snow, the fatbike rules. My experience on sand is that the fatbike performs really well.

Greg - 02/07/13 - 2:34pm

@ King Country,
We did a ride at an undisclosed location here in the 4 corners area of New Mexico and we were constantly going in an out and through and down an arroyo (spanish for wash or dry creek). My buddy on fatbike never even slowed down…the rest of us were spinning like crazy, often washing out and having to walk.
The point of a Fatbike could not have been made more clearly.


Canucklehead - 02/07/13 - 3:29pm

I got a similar answer when I asked about how Lloyd got Cannondale Hollogram SiSL cranks on a Moots PF30 BB — “my mechanic took care of it”.

Contador - 02/07/13 - 4:13pm

A Canonndale SI crank has a 30mm spindle, why would you need anything special to install on a Moots PF30 BB? Plenty of PF30 bottom bracket options available.

Seitenryu - 02/07/13 - 4:46pm

@Canucklehead — SiSL cranks are compatible with BOTH BB30 and PF30. A hardware substitution needs to be made, but Cannondale makes both types as they make frames of both types as well.

Canucklehead - 02/07/13 - 5:22pm

@Seitenryu: Thx, will talk to my local Cannondale distributor!

Jason - 02/07/13 - 10:21pm

If only there was a way to use a normal crankset on a fat bike. The Q factor on those cranks kills my knees.

Mindless - 02/07/13 - 10:50pm

@Jason: You can use 83mm, if you are willing to live without granny gear. Get DH Isis BB and something like Middleburn with 28t chainwheel and 11-36 rear.

Mindless - 02/07/13 - 11:04pm

P.S. Obviously not for any frame, got to clear chainstays.

Rome - 02/08/13 - 7:18am

Look closely: the axle is not hollow anymore, or at least something is stuffed inside.

leads me to thinking that they cut the axle in two pieces and welded a spacer inside. that spacer has a smaller diameter at both ends, that fits tightly into the old axle, the middle part is just as big as the axle itself is. this way welding is much easier and the spacer is centered nicely. the thingy one can see inside the axle is that spacer. at least this is, what i would try, cause i think swapping the axle itself will likely damage the pressing surface. all you need is a center lathe and a TIG welder.

if one would really like to tech up, the same might be done with a diagonal cut and weld. this would spread the forces while pedaling even better, but the spacer itself is more difficult to produce.

sorry if some words sound funny, i am not a native speaker.


David - 11/01/13 - 2:26pm

Sure Romeo must be right, i am about to attempt this exact modification, a bit of stainless steel, and a pair of unused xt cranks are actually my starting point for building a fatty….
I don,t like parts just lying around…..
Eventually if there is an interest i can share my experience, we will see how this goes… and hopefully i remember making some pics in the heat of the action.
Greatings from Sweden, David

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