Soma Sandworm 650B+ Build

It's been a long, long time coming, but the mythical Sandworms have finally emerged from the bled to take their rightful place at the top of the food chain.

We built this one up with 650b wheels and 3" tires for a more "lively" trail oriented ride.

The Sandworm is made with sturdy Tange Infinity tubing, making it stiffer than the other Soma MTB frames. With tires this wide you don't need the frame to dampen the ride much, so we built it for loaded bike packing and rowdier Enduro routes.

Like several other Soma models, the Sandworms feature a splitter for installing a carbon belt drive.

Originally designed as a single speed crankset, more people have been using these IRD Mjolnir cranks on 1X drivetrains. Since the cranks arms need a bit more clearance to wrap around the wider chainstays, we used the Wolf Tooth 94mm offset chainrings to achieve a perfect chain line. Since it's a square taper design, it offers more flexibility for unusual chain lines such as you'll often find on internal gear hubs.

The outer diameter of these wheels is about the same as the 26" fatbike tires that are popular for softer terrain and snow. This allows the frame to accommodate multiple wheel set if you want to change up your riding style. This carbon fork offer plenty of clearance for even wider tires.

The 55mm IRD Sawtooth 650B+ rims really take advantage of the Panaracer Fat B Nimble's added volume, giving the tires a wider contact patch and better cornering performance.

The hourglass headtubes allow you to run both tapered forks, or straight steerers. Even though we began developing this bike before there were any true fatbike suspension  forks on the market, we knew that we wanted to make sure it would accommodate them when the fork makers finally caught up.

For the cockpit we used my favorite MTB bars the Soma Clarence and a Soma Shotwell 31.8mm stem with Palma Sutra foam grips.

In addition to enabling single speed and Rohloff compatibility, the IRD sliding dropouts allow you to adjust the effective chain stay length to suit your riding style and tire choice. There are so many fat tires on the market these days that we haven't had a chance to test them all, but we have yet to encounter any that don't clear it's curvy stays.

Weather you're building up your first fat bike or swapping out a old one, we think the Sandworm offers a great feature set which allows you to build it the way you want.