I'm in the process of looking for a road bike. Up to this point in life I've never really had a bike fitted to me and I currently have on old Schwinn mountain bike which I know is too small for me. I've taken some measurements at home and used one of the online fit calculators and it says that I need a 59cm frame for a road bike. (6"2' 35'ish inseam - long legs) My question is...how much flexibility do I have with this number? Can I come within a few cm's of it and still be comfortable on a bike or do I need to adhere to this quite closely? I'm presently in the market for a used road bike and I thus don't have the ability to go and buy the perfect sized bike but I also don't want to pass up a sweet deal on a used one that I might see that measures 57cm or 61cm. I'm new to road biking so I'd appreciate any advice you veterans can give.

Thanks!

We are the same size and I ride a 59 c-t-t = 57 c-t-c. If you aren't real flexible, look for a head tube about 200mm or so which will complement your 35" inseam without too big a saddle to handlebar drop. The thing you don't want to do if buying say a 58-59cm bike with 180mm head tube is buy one where the fork steerer is cut short. Many that race like to cut the steerer and slam the stem down onto the head tube for low bars. With an uncut steerer you can space up the stem to get the bars higher. This is one of the reasons I tend to buy new.
Good Luck.

I've got similar measurements and was wondering the same thing. Fit calculators like competitivecyclist's recommend I ride a 59, but I used to race a 61cm Bianchi Veloce and was comfortable on it. Is there any disadvantage to riding a frame one size too big?

The length of the top tube is the most important measure, followed by the height of the head tube.

I'm your size and ride 60cm bikes, with 59 to 60cm top tubes. I like to sit up a bit higher, so I go for ~20cm head tubes. I also have gorilla-long arms, which may explain my preference for a long reach.

If the frame is too big, you'll be stretched out too long, which is hard on your back, shoulders and hands. Also (from personal experience) you'll have to work hard to avoid knee issues (from your weight being far forward), crappy power up steep hills (from your center of gravity being too far back over the rear wheel) or saddle sore problems (hips being canted too far forward so you put weight on your taint instead of your sit bones). You can compensate a bit with a short stem, but then the handling of the bike suffers. Try to keep around a 90-110mm stem for your size.

Bianchis have a very forgiving geometry...somewhere between comfort and normal and maintaining the Italian tradition of squarely proportioned frames...virtual seat tube length = top tube length...or close. A 61 has a 585mm top tube with 72.5 deg sta and why it worked well for you...a tall frame for its length if you will. The disadvantage to riding a bike too big is multi-fold but in summary, if the top tube is too long you will require a shorter stem and your body CG will not be centered in the sweetspot of the frame. 1 size up bikes tend to be a bit more comfortable for the average recreational rider provided you aren't too stretched out...because the head tube is longer and the handlebar position is higher relative to the saddle.
HTH.