With one exception (as far as we can recall off the top of our heads) FatBikes require wider than normal hubs. This isn’t because you can’t build a wheel that incorporates a wide rim and wide tire with a conventional hub – that in and of itself would be no problem at all. Rather the issue has to do with chain rub, which is the paramount issue with all FatBike setups.
On another page on this site we write about wide FatBike cranksets and bottom brackets, and this is effectively the other half of the equation. We sell Surly and Salsa FatBikes, and although both manufacturers use unconventional hub set ups here’s the basic difference between the two:
Surly’s use a conventional rear 135mm hub in both the front and the rear of MOST of their FatBikes. It’s also worth noting that the Pugsley is available with an offset front fork that matches the offset of the rear of the frame perfectly, so you can dish the front and rear wheels identically and as a result the wheels can be interchangeable front and rear. If you want to swap the hubs out trail-side you’ll need some kind of cassette, freewheel, or at least a fixie cog on the front hub.
Because the Pugsley has horizontal dropouts with a derailleur hanger it can easily be set up as a geared or a single speed bike, even on the fly, so many people set theirs up with a hub and cassette in the rear and a single speed ‘rear’ 135mm hub with single speed freewheel or fixie cog in the front. If the rear hub freewheel mechanism (commonly called a freehub because the freewheel and hub are integrated) freezes up and refuses to engage (as sometimes happens in really cold conditions) you can swap around the wheels and use the ‘front’ wheel with either a single speed freewheel or a fixie cog to get you home. The single speed freewheel may suffer the same fate as your freehub and freeze up but it’s worth a shot (it’s also a bit easier to ‘winterize’ your freewheel with lighter oil or grease compared to a freehub, but those details are for another post), and your fixie will obviously be guaranteed to work because it doesn’t contain any moving parts.
If you’re not concerned with swapping your Pugsley wheels between front and rear you can run a front specific 135mm hub, meaning there’s no accommodation for a cassette, freewheel, or fixie cog. This saves a bit of weight. You can also build a stronger wheel for the front by choosing a non-offset front fork for the Puglsey, which in turn enables you to build a non-dished front wheel. This makes no difference to the type of hub you use up front, but it means that your wheels are no longer swappable front and rear even if you use the same hubs and cassette/freewheel/cog set up front and year (in fact there would be no point to use anything up front but a front specific 135mm hub if the wheel isn’t dished and can’t be swapped anyway). Yet another option available for the Pugsley is a 100mm wide non-offset front fork that uses a conventional 100mm front hub. This is the lightest set up of all but requires deflation of the front tire or removal of the front brake calliper in order to get the front wheel into or out of the fork.
Confused yet? Well then take a look at the Salsa’s, which are a bit more straightforward:
Salsa’s use a 135mm hub in the front and a 170mm-190mm in the rear on MOST of their FatBikes. Neither the front nor the rear fork/frame is offset, and the front wheel isn’t dished. Essentially Salsa’s FatBikes look exactly like conventional mountain bikes except that instead of 100mm and 135mm hubs front and rear they employ a 135mm and 170mm-190mm hub so that everything is a bit wider. You can use any 135mm hub you want up front (so long as it uses the same quick release or thru axle as the fork), but there would be no point in using a hub that accommodated a cassette/freewheel/cog because the wheels aren’t interchangeable and it would just add weight.
Newer Mukluks (2013 and beyond) use an “Enabler” rear dropout that allows you to easily single speed the drivetrain, but we’re not aware of any 170mm single speed specific hub at the time of this posting so even if you run a single speed set up you need to use a ‘regular’ 170mm hub with a single cog and a bunch of spacers where the rest of the cassette would otherwise go.
Surley and Salsa both make their own hubs for their stock FatBike set ups and for after market purchase if you want to build up your own wheels, but the list of other aftermarket FatBike hubs is growing daily. We really like some of the offerings from Hope and Paul Components right now, among others.