Colnago C40 51cm

Looking to get back into more road riding and train for and compete in a Centurion perhaps at the end of the summer. Lots of hills. Long hiatus after doing triathlons. Sold my Cervelo Tri bike years ago and I have a chance to pick up a Colnago C40 used, 51cm with a 51cm top tube. My experience has always been to get a really good bike used is better than spending the same on a lesser quality new bike and this would be in the top end of my budget. However, because I am not going to a store I don't have the luxury of a fitting or size choice. I will try the bike before I decide but wanted to get an idea of whether there was any point in trying it out. Getting mixed messages on what I could find online in Colnago sizing.

I am 5'4" and very proportional. Have about a 30" inseam. I ride a Surly Crosscheck 50cm comfortably. The top tube on the Surly is closer to 53cm from the current specs but also bought this a long time ago and don't know if specs have changed. Will measure tonight when I am home to be sure. What is the thinking? I won't bother trying it out if consensus is it will be too big and will wait for something else to catch my eye (or buy something less spectacular new).

If you can comfortably ride a 50cm Cross Check (they have tweaked the geometry recently, and they're even longer in the TT than they were in the past), I would say that the Colnago is going to be on the small side.

Torso length-wise, we're probably similar. My CX bike has a 53cm ETT, though on a Cross Check I'd be more comfortable on a 46cm. I'd feel really cramped on something with a 51cm ETT. You could put a longer stem on it, but my guess is that it already comes with a 90-100mm stem, and I wouldn't go beyond 110mm because of how it affects handling.

Mine was an old crosscheck so the designation, geometry might be different. Don't think is a 50 after all, more like the 46 I think. I actually had remembered it as a 48 or 49 but when I didn't see that option thought it had to be bigger than the 46 so went 50. Whatever its designation measurements show about a 51cm top tube but a shorter seat tube at closer to 46cm. So reach might be okay but standover and seat position might be more awkward and less adjustable. I have my crosscheck seat elevated a couple of inches so it may be doable.

Worth a try?

I'm 5'4" too, and my Colnagos range from 48-51, because their geometry changes often. I find that if the toptube measurement is good, the rest will follow. So, they all have around a 51-52cm toptube, and I'm good. I love my C40!