I have a Fat Bike in the bush of Alaska and have purchased a BOB Trailer. The standard fork is too short. My wheels are Surley endomorph 3.7, 26″. Will the long fork work with this set-up?
Mounting a BOB Trailer fork is possible on some fat bikes but will generally requires modification to the fork or other odd fixes.
You’ll need to determine what style of fat bike that you have. Is the frame offset with a 135mm hub or is it symmetrical with a 170mm hub? This article over at TwentyNineInches.com does a good job of explaining the differences and reasons behind the two styles.
I”m guessing that you have a symmetrical setup for your rear hub. In this case, you would need to modify a BOB Trailer Fork (28 size). This fork has spacing for 130 to 145mm hubs. The fork would need to be spread out equally between 30 to 40mm. This could be likely be done by a local machinist or metal worker.
With the wider fork, there is not a wide enough quick release. The BOB Trailer quick release for Santana hubs is designed for 160mm wide hubs. This generally is little shy for the 170mm wide hubs on symmetrically spaced fat bikes. The only option is if you have a way to mount BOB Nutz somewhere on the frame, perhaps to rack eyelets.
*Please note: the BOB Santana fork is not an option because though it is spaced wide enough, it does not have sufficient clearance for the massive 4″ tires.
If you have an offset setup on the rear hub, the BOB Trailer fork would need to be bent around 30 to 40mm to the right side. Have a look at this article at the Surly Blog with some good photos of a BOB Trailer fork mounted on a Surly Pugsley.
Take a look at this MTBR article for more discussions on the matter and some great photos of a nice fat bike setup.
If you have a non symmetrical 135 mm wide hub. It is possible to have a BOB fork modified and bent over to line up with the hub. In this case, the standard BOB quick release will work.
*Please note: Modifying the BOB Trailer fork to fit on hub spacings that it was not designed to work on will void the fork warranty. Give the folks at BOB Trailers a shout and suggest that they look into offering forks designed to work with fat bikes.