SOC13: Devise Cycles’ Radical Adaptrac Equipped Zeppelin Fatbike
If you’re unfamiliar with Adaptrac, just imagine riding your bike and being able to instantly change your tire pressure, as you ride, without ever getting out a pump. Crazy, right? Just over a year ago, Adaptrac launched their on board tire pressure management system at Sea Otter. This year, to show off Adaptrac’s possibilities for the fatbike world, Brandt Weibezahn who is the man behind both Adaptrac and Devise Cycles, decided to build a wild full suspension fatbike complete with a linear suspension design, built in c02 expansion chamber, and a custom Maverick fork.
We get a closer look at the Zeppelin after the break.
At the heart of the Zeppelin is the reason for building it in the first place – the Adaptrac tire pressure management system. Since the Zeppelin was built to use the system specifically, Brandt decided to build a custom frame that would utilize a sealed downtube as an expansion chamber for the c02 used to inflate the tires. C02 is stored in the bottle mounted to the downtube then allowed to flow into the tube of the bike where it expands and is allowed to come up to ambient temperature, and from there flows into regulator and switches mounted to the bars.
While standard Maverick forks have been used for fatbikes with smaller tires and rims, Brandt wanted to be able to use a full size fatbike wheel and tire so he chopped up a Maverick to make it work. The new fork, named the Dinner Fork features custom triple clamps to mount to fork tubes which was no small feat since the lower Maverick clamps are actually welded on. Each tube had to be carefully machined down to precise dimensions to allow for the custom lower clamp which is just one example of some amazing machining displayed on the Zeppelin. Since custom clamps were already being made, the upper was designed to incorporate pressure gauges for each tire to see what pressure you’re running.
Of course if you space out the fork legs, you’ll have to make a wider hub as well which is exactly what they did. The new hub is 135mm wide, still using Maverick’s 24mm thru axle design, with an offset hub body that allows the in-line to enter the axle on the outside of the hub, and the out-line exits hub center. The configuration of the hoses permanently connected to the valve stem is what allows for inflation on the go.
The rear is a 170mm wide symmetrical thru axle hub with the co2 line entering the drive side of the axle.
When asked about the linear rear suspension that rides on a a Cane Creek Double Barrel coil rear shock mounted inline with the seat tube, Brant says it was something he always wanted to try. The entire rear swingarm slides up and down on the two shafts mounted on either side of the shock thanks to recirculating ball bearings. The upper shock mount is attached to the front triangle, and the bottom shock mount is attached to the swingarm, while the glide rods hold the front triangle together. Due to the angle of the rear suspension and the front fork, the front and rear tire have the exact same axle path. If nothing else it is a feat of machining and fabrication just to make it work.
Custom parts were all over the place on the Zeppelin. While XX1 fatbike cranks are coming, in the mean time if you want one on your bike you’ll have to get creative like Brandt. A standard XX1 crank was cut, surface ground, and then extended and machined to make a 100mm wide crank for the Zeppelin.