MerckxMad

Um, I'm not sure that I understand your point. I think we agree that tire clearances are greater on a CX bike than a road bike and that the BB's are usually higher, but you lose me on the standover height part. Tire size and BB height have little to do with bike fit (although BB height can impact chainstay length). The standover height is determined by the length of the tubes, the HT angle and whether the TT is sloping or not (few CX'ers do), but it typically does not factor into fitting for a either a road bike or CX bike. Unless you're doing dismounts incorrectly, or you ride the crosser over really rough stuff that requires you to dismount and straddle the bike, standover height is kinda irrelevant.

As far as comparing the two types of bikes side by side, I'm not sure that means anything as far as fit goes. The cockpits of my 54cm Kona SS Paddywagon and my 54cm Kona Jake are virtually identical even though the tube lengths, angles and BB heights are slightly different. Not sure how this helps the OP.

Mike552

While your analogy stands true if one were to compare only one form of bike (i.e., a road bike), but because we are speaking comparatively about two different (which has been the predominant argument in this thread) designs, road AND cx, then it is logical that your above quoted statement is wrong.

YungBurke

A small frame doesn't, but a properly fitted frame makes mount/dismount much easier.

ronbridal

[QUOTE=MerckxMad;8221955]The standover height is determined by the length of the tubes, the HT angle and whether the TT is sloping or not (few CX'ers do), but it typically does not factor into fitting for a either a road bike or CX bike.QUOTE]

I may be wrong, but I think bottom bracket height also figures into standover as well. If the bb height is higher on a given bike than another, and the tubes are the same length, would it not result in a higher standover?

It is also worth mentioning that many manufacturers of cx bikes are using what is more commonly referred to as American geometry. Meaning, the bottom brackets are lower than traditional European (Belgian) made bikes.

ronbridal

A smaller bike (combination of wheels and frame) does make a difference in mounting.

The amount of drop and wheelbase relative to control is subjective. What works for one doesn't work for another.

MerckxMad

[QUOTE] I may be wrong, but I think bottom bracket height also figures into standover as well. If the bb height is higher on a given bike than another, and the tubes are the same length, would it not result in a higher standover? [QUOTE]

No, because while the HT and ST angles change (and possibly the downtube length), the standover height does not. For example, my Kona SS and CX have similar TT and ST lengths (2mm difference in TT), but the standover height is virtually identical (taking into account the diameter of the TT). I always believed that the BB height had more to do with clearance and possibly chainstay length than geometry of the main triangle.

It funny that you mention lower American BB heights because my (Belgian-made/market) Merckx frames have relatively low BB's compared to my other bikes.

guelphite

I’m 5’8” and 54 cm fits me. I didn’t read all the info above but this should fit you, albeit some tweaking from seatpost set back and stem length.
I have a Lyndsey which was assembled and fitted by someone who is building bikes for racers. My favourite bike to ride.

Some 53 cm’s don’t fit well and I’ve had 56 cm and it’s too big for me.

Saying that, do a test ride. You may not like the ride but do a fit. You won’t regret it.

Happy Trails.