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Sizing a CX bike(8 posts)

Sizing a CX bikeScooderdude
Nov 23, 2001 10:32 AM
After stints with MTB, SS, and DH racing, I'm thinking of CX now. I need help sizing a frame. My road bike is ~56cm (~22"). I have a 32" inseam, and stand 5'10". I hear the CX bike should be a bit smaller, but how much smaller? Is there a point of diminishing return in terms of "smaller is better"? I have my eyes on a buddy's 50cm Independent Fabrication CX bike, nicely built. Is this too small?
re: Sizing a CX bikeElvis Karate
Nov 23, 2001 7:52 PM
The best way to size a bike is to ride. But I can tell you a 50 cm bike will not work for you. My cross frame is smaller in seat tube measurement but longer in the top tube than my road bike. And yes it is a frame size smaller but the bikes are different brands. I also run a shorter stem on the CX. Since all bikes are differnt and somebody's 56 is anothers 58 or 54 it is tough to call. I ride with alot of people who run the same size road and cross bike and have no problems.
It sounds like your legs are porpotionately a little longer than your torso so I would try a 54 or 55 but don't be afraid to ride a 56 if it is comfortable and you have clearance. Cyclocross is fun and you should love it!
re: Sizing a CX bikebuffalosorrow
Nov 25, 2001 12:03 PM
I am 5'8 and have a a 32.5" inseam with shoes, I have a 52cm center to top, and just have another frame custom built to this size the top tube vary from 54cm to 54.5cm, I pefer 2-3's" stand over. It does not matter huch as long as you are comfortable, hoping on an off your ride. IF's are nice I had my custom Graham Weigh designed after their geo. The 50cm sounds a hair small if measured center to top, if it is a 52cm c-t try is for a spin.
re: Sizing a CX bikedylio
Nov 27, 2001 10:01 AM
I'd say the 50cm IF would be a bit too small for you. I usually ride about a 56 road bike too, and I'm similar to your height (maybe a little more length in my torso).
You'd be better off looking for a cross bike with the same length or half a cm shorter top tube as your road bike. Then set it up with a stem 1 cm shorter than you normally use, and set it up higher than your road bike.
Stand over height matters, but not as much as a mountain bike. Remember, a cross bike has a taller bb than a road bike, so the bike is going to be higher anyway. On a cross bike, you're jumping off the bike, and then back on - all over the top of the seat. As long as you have an inch or so of stand-over clearance, you'll be good. The bigger front triangle also makes for more room when you shoulder the bike for run-ups in a race.
Happy shopping.
re: Just curiousSteveS
Nov 29, 2001 10:39 PM
Since I am new to cyclocross, I am curious as to why the stem would be 1 cm shorter than on the road. Does it improve the general handling offroad?
re: Just curiousdylio
Dec 10, 2001 10:46 AM
Yeah, it helps improve offroad handling. It just puts you in a more upright riding position, much the same way as a riser bar does on a mountain bike.
With a longer stem, you have more of your weight over the front wheel, which makes the bike a little bit more "twitchy." Being more upright puts your weight more to the middle of the front and rear wheels making everything a little bit more stable.
re: Sizing a CX bikeScooderdude
Nov 29, 2001 10:52 AM
Hey, thanks for all the replies. The 50cm IF CX bike is measured c-c. The TT is a bit shorter on the IF than that of my road bike (both ST and TT on the road bike are ~56cm c-c). So, sad as it may be, the nicely-spec'd IR may be too small.
re: Sizing a CX bikeMasterBlaster
Dec 1, 2001 9:26 PM
You can also go one size down what you would normally ride on the road (I.E. 60 cm road frame = 59 cm CX frame.In my humble opinion TT length is most important. If you have a longer upper torso try a Lemond. I test road several road / CX bikes before deciding on a Lemond Poprad (59 cm square). Good luck!