I wanted to get a few rides on the single speed before rendering a judgment on how the project turned out. Geared with a 50-tooth chain ring up front and a 20-tooth cog for my flat commute I put it through its paces last week. I'm happy to report that 2.5:1 ratio was pretty much spot on. The speeds I was seeing on the Garmin matched the numbers when I checked Sheldon Brown's Bicycle Gear Calculator. A very rideable 15.5 mph @ 80 rpm, 17.5 mph @ 90 rpm and 19.5 mph @ 100 rpm. Easy enough on the knees from a standstill, tall enough to cruise along without feeling like a hamster.
The last time I rode a bike with one gear it was a green CCM with high handlebars, a banana seat and a coaster brake. Carbon was just an element on the periodic table back then.
The Trek's full-carbon frame provides a lot of damping rolling with the original Bontrager Select wheelset sporting a new pair of Continental GP 4-Season tires. After the stiffness of my Eulogy, the 7.9fx is a bit noodley. The longer wheelbase and relaxed angle of the hybrid's seatstays have more flex than a road bike. The extended wheelbase has one benefit though, no toe overlap. I can turn on a dime and not have to worry about stubbing my toe on my front tire.
Mykle Kong, Tech Manager at San Jose Trek did the build while I photographed his usual meticulous work. First step was to strip the frame of the gear we'd be replacing: straight bar, levers and shifters; v-brakes; front and rear derailleurs. Then it was time to prep the rear wheel. Mykle removed the cassette cleaned up the hub and then test fit the Chris King Spacers and 20t Stainless Steel Cog. Virtually every guy in the store came by to check out the beautiful CK jewelry.
Since the bike's primary purpose was as my commute on pavement I wasn't worried about chain ring clearance (like a cross bike) so I opted for a large ring/large cog combination to achieve the gearing. By maximizing chain engagement I should get longer service from the components. The reconfigured 105 triple running the single, outer ring looks very clean from the drive side of the bike, but a little less appealing from the left. At some point I might switch the cranks for a dedicated track setup from Sugino or Miche, there's no hurry though.
Mykle installed Shimano's Alfine chain tensioner to complete the drive train. I hadn't been impressed with the look of the chain tensionsers from Surly etc. The Alfine, available in silver and black, looks like a derailleur with its twin pulleys. My only problem was finding one, apparently there's not much call for them in the U.S. Eventually I had to purchase it from a shop in the UK. To keep the Alfine in a nice compact configuration we spliced two SRAM chains together and then trimmed the excess links. While there is some room for inboard/outboard adjustment on the Shimano tensioner Mykle decided to move the cog inboard one spacer to improve the chain line.
A spin of the cranks confirmed the setup was efficient and quiet. In fact, riding the bike the first few times was almost too quiet. The freewheel action of the Bontrager hub is a whisper compared to the audible reassurance of my Campy, Topolino and Ligero hubs. Minimal chain noise and the missing punctuation of shifts had me wondering if the bike was working at times.
In the braking department I've been very impressed with TRP 950 cantilevers. As you can see in the gallery, they look incredible. The finish is a very good match for the nude carbon on the Trek. More importantly they really stop the bike. I'd expected a significant compromise in performance compared to my road brakes (and feared they might even lag behind the v-brakes we removed). My concerns were unfounded. The action of the TRPs, front and rear, is smooth and sure. Again Mykle deserves credit for dialing them in perfectly... but these are great brakes. Next week's weather should give me an opportunity to try them in the rain.
The final task was to assemble the new cockpit: FSA K-Force compact bar, Oval Concepts R900 - 110mm stem and Campagnolo Veloce levers. Other than the somewhat awkward installation of the rear-facing bolts on the R900 (looks great when finished though) bar and stem mated well with the steerer. We decided not to remove the shifters from the Veloces in case they were re-purposed for another project down the road. Twice in that first week I found myself ghost shifting... I now regard it as a kind of intelligence test. As Chris DiStefano at CK told me, "with a singlespeed you're always in the wrong gear."
I want to add that the alloy Veloce's share the same basic design as their richer Italian relatives. When I first saw them last year I thought the Vicenza engineers had been looking at their Japanese competition too closely (and coincidentally Shimano seemed to have been looking to Italy for design cues). Only after riding with them do I now appreciate the sublime ergonomics of the new shape and wish I could retrofit my two road bikes with just the 09 levers. Wrap your thumb and forefinger around the enlarged hooks and you have a comfortable, stretched-out position to work with. Bellissimo.
There you have it. I'm quite sure this is the only single speed 7.9fx in the world. Quibbles... here are a couple. The front end is a bit gangly with all that tire clearance and the bike still has noticeably higher center of gravity than my Cervelo or Enigma. But overall it's fun to ride and that was the first goal of the project.