Quote Originally Posted by Miranda View Post
I'm sure someone will come along and correct this notion in my head that I *think* I recall reading somewhere if not right. But...

I believe one reason the bottom bracket is higher up is to be able to clear obstacles. I don't own a cyclecross bike. But it's on my list for the stable. I do own a hardtrail mtb in addition to a roadie girl.

When your terrain such as trail riding is over boulders and fallen trees etc., the lower bottom bracket would be also lower to crash into something. Versus higher like the mtb keeping pedals level with an ump rides right over the tree.

Think of it in terms of a fancy sports car that is very low to the groud, vs a truck that is higher off the ground... one clears stuff easy, one does not.
Um, are you telling me this or who? I know the BB height on a cross bike is higher. I was wondering what the BB height has to do with the top tube length, not the seat tube length, on a cyclocross bike. And I was right - nothing. At least no more than any good bike builder would plan out when designing any bike - road, mtb, or whatever. You still need to pick a bike frame "size" by actual measurements, not by the decal stuck on the bike.

If you read my previous post, you'd see I have a road bike and a cross bike from the same builder in the same size with the same top tube length. But Surly doesn't design this way. Therefore, PscyclePath's comment about a smaller size only applies to Surly and bikes from builders who design similarly - not to all cross bikes.