Bike sizing - does + or - a couple of cm really matter?

El Diego

I'm 6,2" and normally ride a 58cm road bike. I currently ride a Cannondale 6 which has a fairly long headtube and is fairly relaxed for a road bike. I was measured up for this bike and it fits me great.

I've just taken a gamble on a 56cm Ridgeback single speed for commuting. I say a gamble because I bought it online so didn't have a chance to test it, inadvisable I know but it was a bargain. I'm running the seat fairly high and the seat quite far back, so I'm stretched out about the same as on my Cannondale and my leg is extended correctly at lowest point in my pedal stroke. The bike feels like a good fit and I don't get any discomfort after riding it.

Does a couple of cm really matter that much? Does anyone else ride different sized bikes? What are the implications of riding a bike slightly too small (apart from looking like a circus clown)?

cyberknight

It is the top tube length thats matters the most , as long as you can get your seat post at the right height then it is your reach that affects your comfort more than anything else.

I ride 2 bikes , one has a top tube that is 1 cm longer and has a more relaxed geometry so that to get the same saddle setback from BB i need to have the seat as far forward as it will go.Once i did stupidly buy a bike that was to big and although i could get seat height and saddle set back right i could not get my reach right , i tried shorter stems etc etc with no luck and wasted a lot of money just to get back ache.

Now i have learnt what fits me i have written down on a drawing of the bike the essential measurements to replicate my 3 points of contact on a bike so i can ask questions about any bike geometry before deciding if is worth considering it.