Review: 4.8in Fatback Aluminum Fat Bike

Hot on the heels of maddslacker’s long-term review of the 3.5in 3.8in-tired version of Fatback’s aluminum fat bike, I had a chance to take the massive 4.8in version for a spin around the Outerbike test loop.


First, and most obviously, this rig sports the biggest fat bike tires you can buy, at 4.8 inches wide. Hot dang, that’s huge! I’ve ridden singletrack trails that aren’t even 5 inches wide!

The build I rode featured Fatback’s own carbon fork with through-axle, although several bikes at the Fatback booth (which, coincidentally, was right next to ours) were sporting prototype suspension forks.

My test rig was running a SRAM X01 1×11 drivetrain. My first time riding a 1×11, and it’s on a fat bike… just a little ironic! This really is the miracle drivetrain: perfect for everyone from cross country, to downhill, to fat bikes. I never lacked for low-end gears (I had way more gears than I needed for the Outerbike test loop) and shifting was crisp, precise, and rapid. I need to spend more time on one of these.

My test rig was also sporting prototype carbon rims. These rims are brand-new, and all I could get from Fatback were ballparks on what retail would be. And yes, you can set these bad boys up tubeless.

Out on the Trail

Right out of the venue, I decided to see what these fat tires could really do, so I pointed them at the loosest pile of dirt and rocks I could find.

Wait, what pile of dirt and rocks? This bike turns what would be a horrendous, endo-enducing idea on a normal mountain bike into what essentially feels like a packed singletrack trail. Braaap!!!

After that little foray I decided to rail some singletrack, to see how it would perform. As maddslacker mentioned in his review, traction was phenomenal! I was able to power up absolutely everything without hesitation.

To test out the resilience of this rig as a trail bike, I pinned it through every rough, gnarly section of trail without a second thought. While yes, the ride wasn’t as smooth as my full suspension rig would have been, it didn’t bobble or get hung up in even horrible line choices. I do think the tires were set up quite a bit firmer out of the booth than most experienced fat bike riders would have ridden them, so I imagine that small bump absorption could easily have been improved with a drop in tire pressure.

The final thing that amazed me about this rig was the traction in the turns. Despite the massive tire/wheel combo, the Fatback didn’t feel ponderous, even in the least. The final descent back to the Outerbike venue features a long section of fast back-to-back bermed turns, and the Fatback just sailed through them, the fat tires humming in the corners with more traction than I could even begin to fathom!

Bottom Line

I’ve watched some peoples’ posts on Facebook who’ve purchased fat bikes for winter riding, and suddenly their carbon full-suspension wonder machines are gathering dust all summer long as well. While I don’t think I’m willing to commit to a fat bike as my only mountain bike, after my experience riding the Fatback all I can say is: “I want one.”

Frame MSRP: $850