The idea to try a 650B bike had also been rattling around in my noggin, and Carver makes a bike with the â€œtweenerâ€ wheel size by the name of Killer B, so thatâ€™s what I got. Carver is apparently unafraid of bucking convention, being a pioneer not only in messing with wheel sizes other than 26â€, but in mixing and matchingâ€”a review of the aluminum-frame 96â€™er from issue #118 is here. The idea of a 650B rear/29â€ front (or should I say 27.5â€/29â€ to avoid mixing units) was appealing, but since Iâ€™d never swung a leg over a tweener, I figured I should go with that for simplicity.
The bike arrived a mere two days before the SM100. Normally a race of that magnitude on an unfamiliar bike would be a big mistake, and one of the more careful planners in the office shook his head at my folly (that would be Justin of course), but as this is a fairly straightforward bike aside from the less-common wheel size, I figured it would turn out OK. The geometry measurements on this titanium hardtail were not too different from those of my Moots Mooto-X 29er singlespeed. I did swap out the Magura Louise brakes it came with for some previous testers, the Hayes El Caminos, that had a more favorable range of lever reach adjustment; good advice from Eric, since I would be squeezing those levers for hours at a time on the hundred-mile course. I also borrowed the Carver MyTi bar that Eric had recently tested (issue #144) for some comfy alt-bar action, and was damn glad I did. â€œNormalâ€ straight bars feel strange to me now, and months-old wrist injuries speak up unless my bars are sufficiently bent.
The Killer B and I got along well right off the bat. (Whew.) The SM100 course is a mix of road, gravel, dirt and some of the most fun singletrack Iâ€™ve experienced, which made all the rest worthwhile. This being Virginia it has some rocky sections, but also some smooth and fast-flowing sections. The Killer B fit right in and handled it all with assurance, and I couldnâ€™t help but think in Goldilocks terms about the wheel size: not so small as to feel sketchy and get hung up like 26ers can in the bumpy stuff, but not so big as to give up any quick-steering control in tight turns. Since drinking the 29er Kool-Aid Iâ€™ve maintained that their steering is not so much slower that it takes away from their sure-footedness, but I have to admitâ€”it was nice to be able to fling the bike around with more ease, rather than needing to mindfully pilot it in tight sections, if that makes any sense.
The wheels on my tester were a little on the beefy side, with Velocity Blunt rims laced to Shimano XT hubs. For racing I wouldnâ€™t mind a lighter pair. But the 28mm rim width gave the Pacenti NeoMoto tires a nice wide footprint. I tried not to think about the extra weight while climbing the mountain ridge.
Singlespeed World Championships in Durango, Colorado. This frame comes equipped with sliding dropouts (an EBB is also an option) so it was an easy task to lose the gears. I usually use a 32×18 gear combo on my Moots 29er, so asked around for a 17-tooth loaner cog to stick with the in-between, just-right theme; but none was to be had, and I heard dire warnings of the steepness of the SSWC course, so I settled for the 32×18 for an effectively smaller gear given the smaller wheels. Good choiceâ€”the elevation effects were brutal. Still, I was glad to have the Killer B as my weapon of choice. In singlespeed mode, the frame stayed nice and stiff, but not harsh, as one would expect from fine titanium. The SSWC course was fairly difficult even aside from the elevation (the Durango peeps really tried to give us the worst theyâ€™ve got, in the grand SSWC tradition), with a ridgetop slabs-of-rock section and some very tightly winding parts. There were moments in the big rocks when I felt like the medium-size wheels were getting sucked into the divots more than big wheels would have. The tight twisty parts were fun though. The Killer Bâ€™s top tube has a slight dip to it, and the rear end overall is fairly compact; the bike feels like it has a nice low center of gravity, and getting off the back and using body English is pretty easy.
One test for the bike, and the 650B wheel size for me, is just beginning â€“ performance in the sloppy stuff. It had been unusually dry in the weeks leading up to the SM100, and Durango wasnâ€™t too muddy despite some rain before that race. Only in the last couple of weeks have I been able to try the Killer B in some proper mud. Add to that a lot of fall leaves for extra slip-n-slide action. So far the bike has behaved about like I thought it would, slightly more likely to lose traction, but not so much that itâ€™s jarring. On wet roots, I still might prefer to go big (in wheel size, that is)
The next event on the radar is not so long, but the conditions can be harsh: our own Punk Bike Enduro. Weâ€™ll see how the Killer B and I fare. Winter, here we come.