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I have the opportunity to buy a very nice used cross bike at a great price. But, I'm worried about it being a tad bit too big.

It has large Blue frameset with the following measurements:

  • Top tube length: 58cm
  • Seat tube length: 55cm
  • Head tube length: 16cm

My two road bikes, both of which fit me well have the following:

  • TT: 56.5 & 57
  • ST: 53 & 55
  • HT: 16 and 15.5

The head tube and seat tube sizes seem to be fine. But, the top tube length worries me. Since it is only 1cm between the cross bike and my 2nd road bike, I'm thinking it might work if I put a slightly shorter stem onto the new bike, and potentially raise the stack height.

Any input on this would be appreciated.

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1  
Can you try the bike first? I'd think that it would probably work with a stem and saddle adjustment, but there is a geometry change. –  Batman Mar 9 at 2:28
    
I have tried it as-is. Feels quite aggressive but I still feel I have control. Can try it out again soon. But, am curious as to what I should try changing. –  Richard P Mar 9 at 2:33
    
Well, it depends on the road bikes as well as the cross bike (where they fit in the type of bikes). –  Batman Mar 9 at 2:42
    
If its that good a deal, buy it and if it proves to be too big, sell it on –  PeteH Mar 9 at 7:47
1  
Cross bikes often have longer whellbase because of steering needs, so you can buy this bike worryless. –  constpetrov Mar 11 at 10:59

1 Answer 1

Your current top tube, seat tube and head tube only give scratch the surface of bike fitting. Your proportions, seat tube angle, BB drop and frame stack are also important factors to getting a great fig.

Caveat aside, 10mm in a bike's reach is relatively easy difference to accommodate by changing:

  • stack height (spacers or flipping the stem)
  • shorter reach road bars
  • shorter stem
  • even choice of shifter/brakes brand can tighten up the reach a bit

I personally prefer playing with a shorter reach bar and stack height before going to a shorter stem. Depending on how much drop you currently have on your road bar, a higher stack may be all that is required. If it you currently have a large amount of drop on the road bike, riding a bike with more stack - less drop on the handle bars - will require more reach to feel comfortable (otherwise you end up feeling cramped). You can draw an imaginary arc by holding your arms constant and pivoting on hips to see how much reach gain you may want for a more upright position. At some point of course if the stack is too high (ridiculously high) you will again want a shorter reach.

Again this is personal preference, but a higher stack also makes sense on a cyclocross bikes (and training bikes). The bike is more manageable on rough terrain and easier to mount/dismount with a bit more stack. It is interesting that so many cross bikes being sold now are so slammed (in terms of frame stack), I suspect this is so they can "look right" when being marketed as a cross-over bike for those that want a winter or training road bike and not necessarily a cyclocross only bike.

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