Fatbike impressions

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With only 4 rides on my fatbike, I’ve realized it’s like no other bike you can imagine. I’ve had to learn to ride a bike again. On snow, you have to minimize sudden movements and steering stability is premium if you want to stay vertical.  It is SO easy to wash out these tires, they have very little cornering traction even at 10psi.  It’s not the tire, it’s the snow.  Uphill/climbing is more difficult than I’d ever have expected. I’m in granny gear a LOT. A smooth cadence and little upper body movement make it possible on soft snow but I’m usually walking anything over a 5% slope.  Unless the snow is packed down by something heavier than you and your bike, you’ll be swimming in the front and spinning out in the rear.  We don’t get many snowmobilers up where I ride so the main ‘packer’ is snowshoers.  Get enough of them out on the trails and it makes for a pretty good trail. But after each snowfall you kinda have to wait until they get out there and pack the trail down again.

But today, with a week of really well packed down trail use, I got out to ride for an hour with a few inches of fresh snow on top. We get really light low density snow where i live so the snow doesn’t grip but it gets out of the way pretty well. Cornering makes a bit of a rooster tail from the tire, like skiing or snowboarding.  The one fun thing I’ve learned about downhilling on snowbikes is that it’s OK to skid.  It’s not really skidding since your rear wheel is more of a rudder than a stopping device…so don’t worry about any trail damage. When ‘skidding’ the rear wheel around turns, you gotta keep your front upright and centered and almost counter steer like you do in a car when you’re losing control on ice.  It’s way more subtle than that, but if you’re going fast enough on the snow there’s definitely some similarities.  Going down swoopy singletrack on snow is just insanely fun! It does have a similar feeling to a pow day on skis or board but for now at least, i feel a bit less in control.

Oh, and I’ve been checking out the mtbr Fatbike forum and found this lil video.  Sweet singletrack snow ride up in Seward, AK!

As for the geometry and setup of fatbikes…

  • i think going with slacker head tube and seat tube angles is important to keep the weight on your rear tire and less weight on the front which will just wash out if you’re weighting it too much. (*EDIT: After more thought and riding the bike, I would go with a steeper head tube angle than what is available in stock geometry right now.  That is, unless you can get a custom fork that has a larger offset to reduce the ‘trail’ figure.  I would stick with a more normal HT angle like 71 degrees if you make or get a custom frame.  The reason is, I am of the opinion that you need a more stable bike at slow speeds which means a lower trail figure – less than 80mm. At least in the majority of areas I ride right now in Colorado where there are hills and you are trying to stay on the packed part of the trail, you do not need any wheel-flop.  All non-custom Fatbike forks on the market (White Bros, Surly, Black Sheep) come in at 42mm, 43, and 46mm of offset/rake, respectively. So, unless you can go with a super steep head tube angle — say 72 or 73 degrees — you will be riding a bike with at least 83mm trail range and may even be at 90mm with the White Brother’s fork. That is more trail than a “trail” bike like the Rumblefish has! Not necessary for a snow bike. Not sure why this is the case, but do the math and you’ll see what I mean.  For a snowbike, this appears truly excessive.  When are you really going that fast that you need stability at speed?
  • Higher bars – at least level with your seat – and shorter cranks are my preference.
  • I’d also go with a wide range 1×9 gearing but as I said the granny is used a lot if you’re on anything but flat land.  If I could pull it off, I’d go with an internal hub and not risk the freezing up of the rear cogs. I’m going to have to try the BFL (Big Fat Larry) tire when I build a bigger fork for this frame…it’s a bunch bigger than the regular Larry and should float the front end better.  I’m also going to try flat pedals instead of clipless…just because of the snow packing the cleats and also just because of how much you end up dabbing and walking on the trails I ride…it’ll be a better (and warmer) setup.

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