Wednesday, November 19, 2014
anatomy of a useful cyclocross bike
It was a leap of faith having never ridden a bike with low trail geometry before, but I ordered a 700c Boulder brevet. Mike Kone was really helpful with ordering the bike. He provided a detailed diagram of the geometry of the bike to be, including seat height, reach, and drop. Its nice to not have any surprises there when you already know what size bike works for you. Happy to say, nearing the end of my second season on this bike, that it was a complete success. I love this bike! A lot of people have expressed admiration of this bike, but surprise that I would use it for cyclocross. I'll line out where this bike differs from a typical cyclocross bike, and how that shakes out:
1. Low trail geometry. Most cyclocross bikes have about the same geometry as a road racing bike designed for 23mm tires: 72 or 73 degree head tube, and the near-universal 45mm of fork offset. The Boulder has a 73 degree head tube but 60mm of offset. How does it ride? At speed and on pavement it feels a little different but still plenty stable. I have never once felt that I exceeded the speed limit of the bike. Where it really shines is at lower speeds on tight technical terrain- the realm of cyclocross. This bike simply handles better on off camber, tricky terrain due to less wheel flop than my old bike with the typical geometry. I believe cyclocross bikes are better off with more fork offset than 45mm. Unfortunately, 50mm offset is the most you can find with typical carbon cross forks.
2. Its steel, and the fork is steel! Steel gets a bad rap for racing bikes because most steel bikes are built with thick, overly stiff tubing, that doesn't result in a zippy ride. The Boulder is made with relatively light, thin wall tubing. It is zippy! Weight is less important but my 57cm bike weighs 19 pounds, without any goofy carbon parts. A carbon bike will weigh less, but a water bottle or so less. I have ridden full carbon bikes, and they have a great ride quality, but I would not say the bike is obviously faster than the Boulder. Of course you have to factor in tires but more on that later. And the steel fork. A properly designed steel fork with a flat crown and curve near the dropouts (as opposed to the current fad of straight legs, to look like carbon forks) has better mud clearance and will actually soak up bumps. A light steel fork is not much heavier than a carbon fork with an alloy steerer, and has a much better ride quality. A full carbon fork is admittedly much lighter but I'm not willing to trust them. They break unexpectedly. I ride at high speeds on rough terrain, and like to use my stuff for a long time. And finally, a steel fork can be made with the right geometry to match the frame. Carbon forks are one-size-fits-all.
3. Low bottom bracket. Most cyclocross bikes have a higher bottom bracket. Its a trade off here. I think the bike with a lower bottom bracket handles a bit better, but you strike the pedals on things a little easier. Overall I prefer the lower bottom bracket.
4. Cable routing. Most cyclocross bikes have cables routed along the top tube to stay out of the way for shouldering the bike and keep mud away from the cables a little better. The Boulder has more traditional cable routing along the down tube. The rear brake cable on the bottom of the top tube does dig in to your shoulder a little bit when carrying the bike. Its a mild annoyance. The cable routing along the down tube is more direct. Even though the cables get dirtier, they still shift better than cables on the top tube. I replace cables and housing less often on the Boulder than I did with my old bike with top tube cable routing.
5. Mike practically insisted on the needle bearing Miche headset. Low trail bikes can be prone to shimmy. A bike that shimmied would be unacceptable to me, so I went for it. My Boulder does not shimmy. The Miche headset gets fouled rather easily in cyclocross conditions. Its not really a big deal, would be even less of a problem if the bike had fenders mounted as intended. Still, there is something to be said for a King headset that you install and never, ever have to touch again.
6. And of course the beauty of the Boulder is that you can easily add alloy fenders, a front rack, and generator lighting and have a first class randoneeur bike. I have not done any organized rando type stuff to date, but I do love to go on long, unsupported, all-road rides. I'm itching to build the Boulder up as intended but right now it is too good of a cyclocross bike. I need two of them!
There you have it. One more note about performance and value for cyclocross. As I said, I have ridden full carbon and titanium bikes that were a little lighter than my steel bike, but still not better performing. The one place I splurge is on tires. I have been riding FMB super mud tubulars on Chris King hubs/Velocity alloy tubular rims. Those tires make all the difference! The traction and low rolling resistance of cotton tubulars at 22 psi is very, very real. You don't need carbon Zipps! You just need the tires that are usually glued to those Zipps.