It’s officially winter, there’s constant snow on the trails, and I’m going to try to ride my bike more this year. In previous years, i commuted a few days a week the 20 miles & ~3000ft elevation loss to Boulder with studded tires on cross or MTB depending on conditions. On the weekends I skied for the most part, but this year I’m building a snowbike and I want to do some trail riding! I guess people are calling them “Fatbikes” now, since people use them for sand riding and just regular riding on trails (and train-tracks!).
I don’t have the wheels and tires yet, but I’m almost done with the fat fork. I’ll getting the McGrath wheelset from Fatbikes.com which are the Rolling Darryl 80mm wide rims with Salsa rear hub and 9zero7 front hub. The tire spacing up top on this fork is just about 4.25″ so I think the 3.7″ Surly Endomorph will fit fine. If not, I’ll just build another! I found a roll of duct tape that is approximately 3.7″ in diameter so I gauged whether I had enough spacing using that. Not ideal, and it is a bit closer than I’d like, but i got carried away filing after coping the crown pieces on the mill (perfectionist without the skill yet is…time-consuming). These pieces are 45mm long (edge to edge) cut at a 30 degree angle. My other segmented forks have been about half that length and cut at a 20 degree angle. The increased angle will help the fork crown clear the downtube since the fork is so wide. These sleeved-segmented style forks are really fun to build but they take a LONG time. I just prefer them though to regular segmented forks.
The Fatbike I’m building is modeled after the Surly Neck Romancer Pug and the accompanying fork. I looked at the specs/geometry of all the fatbikes and just liked that one the best. (I like to copy geometry for my first ‘type’ of a bike to see *why* they make it like they do…then adapt to what I feel it could use. It’s really helped me hone what I like as far as tubing and geometry go.) The Neck Romancer (say that fast) is a NON-offset frame and fork. This means that the rear axle spacing is 170mm (instead of an offset 135mm like the Pugsley and some other frames) and the front is 135mm (the size of a normal bike’s rear axle spacing). The offset 135mm bikes are cool if you want to use ‘regular’ 135mm wide hubs or internally geared hubs like the Rohloff. What the offset does is space the wheel to the drive-side by 17.5mm so your chain doesn’t rub the huge tire. This makes for some funky dished wheels though, as well as some funky bent rear triangle tubes to get it that way. I don’t have the inclination to go that route and I feel like after reading up on this for a bit online…170mm is going to become the new norm. Plus, now they’re making 100mm wide rims and 4.25″ tires! Holy cow. So just like skis, Fatbikes are just getting fatter.