View Full Version : Bike Size 56 or 58?

10-02-2008, 03:02 PM
I'm 6' and have been riding a 58cm road bike for the past two years.

I've had no complaints and even had a professional fitting at river city bikes.

I found a used bike that I want to buy that is also a 58cm. But recently I've had a bunch of people mainly at bike shops tell me I should be on a 56cm.

I'm Looking for some advice on what I should do. 58 has always seemed to fit but maybe I'm just use to a bad fit. I can try a 56 but I'll never really know if its right until I do a long ride.

THanks for the help

10-02-2008, 03:44 PM
I'm 5' 10" with really short legs and I ride a 56 for my nice bike.

I also have a ridiculously small early 70's Japanese bike that I've made fit with the world's longest handlebar stem and seat post. By which I mean to point out that there is a lot you can do with fit, especially if the bike is a tad too small, and less you can do if the bike is too large.

A smaller frame weighs less and is more rigid. The center of gravity might be slightly lower as well.

Under the circumstances, I'd give the 56 a try. Note that you could pretty much emulate your current cockpit position with the correct handlebar stem and seat post, so you wouldn't be measuring the benefit of the smaller frame by the way it feels; it would be more like...how does it corner for me? What's the toe whack like with the smaller frame? Perhaps some other readers might be able to give you ideas of other kinds of things you might notice with the smaller frame.

10-02-2008, 07:57 PM
What did the fitting indicate as the proper center to center frame size?
Seat tube height is a good place to start with frame selection but the frame you choose can initially may not have the proper top tube length. Also, frame geometry can dictate seat tube length. A sloping top tube will result in a shorter equivalent seat tube length. How are you built? What's your torso length? Inseam length?
FYI, I'm 5'11" and ride a 57 center to center.

10-02-2008, 09:28 PM
interesting that you got that advice from the shops. I'm 6'0" and I have 1 bike that's a 56 and one that's a 58. I make the 56 work with some serious adjustments to the seat/stem/bars, but the 58 is really a better fit.
Despite the adjustments, the one thing I notice on the smaller bike is that when in in the drops, it's quite a bit more crunched up - my knees come up closer to my shoulders. I'd say if the professional fitting told you that your 58cm bike works for you, then I wouldn't change. But, of course, not all geometries are equal - I've ridden a different 56cm bike that was just way to small for me no matter how I adjusted it.