The Surly Thing

[Miranda]

So, the bottom bracket vs size thing really is specific to the brand and model, not the class of cyclocross frames.

Just another reason not to look at size labels, but the actual measurements.

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.