08 January 2012

Rohloff-Equipped, Belt Driven Firefly Custom Titanium 29er Mountain Bike

Signature Cycles (NYC) bike shop coordinated with Firefly Bicycles (Boston, MA) to design this 29er mountain bike. The customer was looking for a high-performance, low-maintenance bike to spend more time riding and less time fixing his bike.

The integrated Rohloff SPEEDHUB and Gates Carbon Drive belt system provides a virtually maintenance-free drive train. This combination requires only an annual oil change for the hub, but no other regular maintenance or lubrication. With the belt drive system projected to last over 10,000 miles, this drive train will provide many years of reliable service.

To accommodate the belt drive system, Firefly used a Paragon Machine Works titanium tube splitter on the right seat stay. This provides a clean and simple solution to insert the belt into the frame.

Finishing details include Rohloff-specific cable routing for a clean look and Paragon Machine Works Rocker adjustable dropouts to tension the belt.

Build details
  • Frame: Firefly custom titanium
  • Fork: Fox Shox F29
  • Headset: Chris King Inset
  • Stem: Thomson X4
  • Seatpost: Firefly titanium
  • Shifter: Rohloff
  • Front Hub: Chris King ISO 15mm
  • Rear hub: Rohloff SPEEDHUB 500/14
  • Rims: No Tubes Arch
  • Tires: No Tubes Crow
  • Cranks: Shimano XT
  • Chainring: Gates Carbon Drive Center Track
  • Chain: Gates Carbon Drive Center Track
  • Brakes: Shimano XT
  • Pedals: Shimano DX
  • H2O Cages: King Cage titanium


  1. WOW!! That's a really nice bike!!

  2. That drivetrain and frame should last forever. Why is the seat secured to the seat stays? Hopefully this isn't the rider's commuter bike...

  3. Breathtaking machine.

    Is it possible to run a belt drive with vertical dropouts? In other words, is there a belt tensioner pully available?

  4. Maybe.

    There is no belt tensioner available. Carbon Drive warns against putting pressure on the back of the belt surface causing damage to the belt and installing a tensioner on the front/toothed side of the belt will decrease your belt wrap, leading to an increased likelyhood of the belt slipping.

    However, there are thread-in eccentric bottom brackets available from companies such as Phil Wood and Forward Components. These give you a limited amount of adjustment, but if you choose your pulley and belt sizes based on your chainstay length, then it is possible to get this to work.

    Don't forget that the frame needs an opening for inserting the belt. If you were going to have a frame modified to have this opening, you could also have adjustable dropouts or an EBB installed.

  5. The owner apparently had a seat stolen off a former bike and didn't want to take any chances with this one.

  6. It's still a long shot. The frame is a '02 Cannondale Scalpel. The rear seat stays are easily opened at the linkage above the rear dropout. But with flexing (suspension) of the chainstays, a tensioner pully would still be needed to absorb it. At almost 46,000 miles, it still runs great with the standard Rohloff chain w/2-pully tensioner.

    My thinking was a tensioner that would push up on the belt from below - if anything increasing belt wrap - from the non-tooth side. Thanks so much, Neil.