CX frame sizing

Midlands Grimpeur

Never ridden a CX bike before and am going to purchase my first one. Looking at a Specialized Crux. Should I go with a size lower than my Tarmac (size 52)?

Reach on both the 49 and 52 crux would be fine but stack on the 52 seems too high. My Tarmac has a stack height of 528mm versus 540mm on the 49 crux and 554mm on the 52 crux. Have read you need 1-2cm more stack on a cross bike but prefer a lower front end which is why I am leaning towards the lower height of the 49 crux.

Any thoughts appreciated.

tgotb

I'd go with the same size as your road frame; 3cm sounds reasonable for the difference between a road and CX setup. You can always use a stem to drop the bar height if you really don't like it. I rode a smaller frame for a year, and it was pretty much a disaster.

The only thing that might force a smaller frame size is standover height, but that's only an issue for quite small riders.

Midlands Grimpeur

Thanks for the advice, checked the standover and it will be fine on the 52 and looks as though there are a couple of spacers under the stem on it as well so I can lower the bars as you say. 52 it is then!

joey54321

I'm in a similar position. I have a pretty low front end on my road bike and finding a cross bike with a similar geometry has ruled quite a few frames out. I think the cannondale caadx/superx has a pretty low front end if you aren't complete decided on the Spesh. The only problem I can think of going with the smaller size is potential reach issues (long stem putting more weight over the front wheel) and possible toe overlap in slow speed corners where you're steering rather than leaning and having to pedal for grip.

trek_dan

The stem on my cross bike is as low as it'll go and still a good inch higher than my road bike. It felt a bit weird at first but I think it really helps with control.

tgotb

Remember that on a cross bike you need to move your weight around a lot more, especially if traction's a bit limited. On hairy descents, for instance, you'll be in the drops; if they're too low you're going to find it hard to get your weight back.