i raced a hot, moderate altitude century on a 'cross bike once. i had road slicks on it, and i was in passable bike shape, but it was definitely a penalty. it's hard to quantify how much you'd give up, exactly, but i was in a lot of pain at the end of that race. i think part of it is needing to modify your expectations about speed - i think i was trying to ride like i was still on my aero road bike . . . and i most definitely was not.

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https://lshtm.academia.edu/MikeCallaghan

http://howtobeswiss.blogspot.ch/

It really should not be much more than a road bike with clip ons, a good set of deep rim wheels will help.

I would think it would be fine with two limitations:
1. need to swap tires to a proper thin road tire
2. You need to look at gearing although that is only a problem if you are a slow cadence masher and tend to ride really fast.


46/11 at 80rpm=26.16mph
46/11 at 100rpm=32.7mph

this is about
53/12 @80rpm=27.67
53/13 @80rpm=25.5

although if you mash
46/11 @60rpm= only 19.6mph

So your going to get lots of recovery on downhills unless you spin 120-130rpm
46/11 @120rpm=39.25mph

It will be restful on downhills but even a 46/11 won't slow you down too much.

Might need a long stem for fit since cross tends to be a more compact geometry with a shorter top tube, but it should work.

Plus cross is more fun, so keep that bike.

Compared to a road bike: Zero time loss.

You might even be faster because the cx bike will beat you up less.

I've done many fast rides, a few races and crits on my cx bike and there is no disadvantage as long as you have suitable gearing and the corners aren't very technical.

Yeah, it's obviously going to be slower, but if you grab some tools it'll be manageable. For starters, I'd swap out the front chain ring for at least a 50. I'd do a really good overhaul of the drive train, including the bottom bracket and the freehub. I can't speak for others, but I don't keep my cross bike drive train nearly in as good of shape as my road and TT bikes. I would want to close that gap. Likely the stem isn't nearly as slammed, so there's that too.

Pretty sure there are no "downhills" at IMMD....