Geared 29er

I have been riding singlespeed only for several years, but wanted to have a geared bike in my fleet again. Ever since my first 29er I have been happy with a single chainring, so this was to be a 1x drivetrain from the start – which meant I could tuck the rear wheel up tight to the seattube without worrying about front derailleur clearance. I spent a lot of time shaping the chainstays to clear the 32T chainring and have decent clearance with a 2.4″ tire. This combined with the curved, ovalised seattube and custom chainstay bridge plate behind the BB shell, allowed me to keep the chainstays down to 415mm. For additional comfort (there is a lot from the big tires run tubeless at 20psi!) the frame is sized so that the titanium seatpost is at full extension for cantilevered flex.

Then having used twin toptubes on the cruiser I built a few years ago, I decided to do something similar on this build. The tubes curve in both planes, with the extra width providing good lateral stiffness to the front triangle, and the twin tubes providing clean routing for the derailleur cable and rear brake hose. I happened to have a piece of headtube sized carbon fibre left, so that went into the front.

With a single ring that isn’t XX1, some sort of chain management is needed, so I added a boss on the seattube and machined a delrin chainkeeper (14g).  For the front end, there is a custom steel fork, with a one-piece stem/steerer, which keeps everything nice and clean (no stem bolts to hit the knees on!), and allows the front hose to run internally from stem to caliper.

The parts kick off with mango R45 disc hubs and headset from Chris King, matching custom decals on the Enve rims, and great color matching for the paint by Eric at Colorworks. An FSA titanium BB, Middleburn Uno cranks, SRAM X.0 9spd derailleur and gripshift and Avid XX brakes complete the build.

This bike was shown at NAHBS 2013 in Denver, and the photos here are by Tina Buescher.

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