size of the frame of course. I'm 6'1 and when I refer to online sizing charts, it says I'm suited for 58 cm. I've only got bikes from craigslist, and my current 2 bikes are both 54 cm. My first road bike from craigslist was 62 or 64 cm I think, and the bar would hit my balls every time my feet touch the ground, so I had to tilt the frame whenever I stopped. So is frame size an exclusively comfort issue, or are there more to it? Smaller frames would be lighter, and will probably be more comfortable too since they allow you to be more upright. How tall are you, and what size is your bike frame?

6 Ft ride 3, 60 cm bikes.

Stand over is only part of the equation. Crank arm length, BB height, seat tube angle, top tube angle and length, stem length/angle, and others...

I'm right around 6' and ride a 22" frame that's rolling on 26" wheels. If the same frame where on 700c/29er, I probably wouldn't be able to clear the top tube. As is, the reach is a bit too far forward (per a different LBS than the one who sold me my bike based upon the standover test).

Unless you live off in BFE, you should spend some time perusing what the LBS has to offer. Your body will be way more helpful in determining what 'fits' more than some text on a screen.

well in my opinion, you won't know what's more comfortable until you've ridden it for 20+ minutes. jumping off a 54 and onto a 56 in a LBS probably won't tell you which one is more comfortable.

Also 6' and currently ride a couple 60cm road bikes. Both were obtained used - if buying new I probably would have been looking more at 58 cm frames. But there's more to the fit than just overall height and seat tube length. Proportions vary and someone with long legs is likely to prefer a little longer seat tube compared to someone of the same height but a longer torso. And the effective top tube length is a big consideration. Minor variations in size can be compensated for by adjusting the stem height and extension.

In my case I test rode both bikes and satisfied myself that they were comfortable for me despite being a little larger than the usual fit formulas would specify.

This topic isn't discussed much here but is almost beaten to death in the road forum.

I'm 5'9" and like to ride with 64-66cm of combined effective top tube & stem length. Of my 2 commuters and road bike, they are categorized as 52, 52 & 51cm frames respectively but all are right around 54cm effective top tube.

But it should give you a better idea of what frame sizes to look for when perusing CL.

And like prathmann said- you're proportions come into play as well. He's my height and rides a couple of 60cm bikes- and I had ZERO clearance when I swung a leg over a 2012 Raleigh Cadent FT1 in a 56.

I looked at the online size charts and thought that the 17.5 hybrid that I bought would be the ticket. I'm not big and only have a 31" inseam. The size guides said that it would be perfect for me. They also said that when standing flat footed that there should be about a 1" space between the top tube and the crotch.

I have the seat post almost at the bottom of the adjustment and were I female the 1" clearance would probably be there.

Show much for "canned" formulas.

Actually, smaller frames force you to raise the saddle and expose more seat post. As saddle height rises relative to the handlebars, you are forced into a more aggressive LESS upright position.

well smaller frames allow you to be more aerodynamic

seriously though, can't you raise the stem along with the saddle?

Aerodynamic may not be comfortable. Depends on your mobility. If you lack flexibility or commute with a backpack or messenger bag, an aerodynamic position may wreak havoc on your back.

Depends on how short you cut your steerer tube. You may or may not be able to move some spacers around and raise the stem. You could buy a new stem that is longer and has a larger rise angle but drastic changes in stem size/length to make a small frame fit will change how the bike handles.

Bottom line. You can ride any bike as long as your feet reach the pedals. But, a properly sized frame will put your body in the best position for good bike handling and efficient pedaling.

5'7" and use 17" mtb frame, not sure what size it would be if it was a road frame. I can adapt to just about any size.

ok. since the saddle is a direct extension of the seat tube and the stem is a direct extension of the head tube, it really shouldn't matter what size as long as it's within reasonable range, right? so if you want to go from 54 cm to 58 cm, just raise the saddle by 4 cm, which isn't a crazy change at all

Online fitting charts are a rough guide for most, and garbage for the rest. I'm 5'8" and 58cm bikes feel best to me -- I feel cramped on anything smaller.

188cm (6'2") and i ride a 58cm hardtail MTB.

When I test rode bicycles, the 19" frame stretched me out too much. The 17" frame fit nicely, though I think one size in between may work too. I am 5'10". Haven't tried road bikes though.

Using a frame with a 54cm seat tube may be crazy when you'd normally ride a 58 of that model.

I ride a 55cm frame with 120mm stem. I'd want a 146mm stem for the 53cm model but might be able to live with a 140 which is the longest commonly available. Two sizes smaller I'd need a 161mm stem which is not available.

I'd also have to hunt around for a super-setback seat post to make the smaller frames work.

+1 on trying out bikes at the LBS. While you might not get as much of a feel as you would on a 20 mile ride, it can still tell you a great deal. For example, I was looking for a new commuter bike recently. I tried comparable bikes from Raleigh, Trek, and Kona - all labeled 58 cm. The Raleigh felt cramped, the Trek was ok but the Kona felt great. These were all lower end hybrids with 700c wheels. Needless to say, I'm now riding a Kona Dew

Not necessarily. A lot of riders use effective top tube as the most important measurement as opposed to seat tube length because of reach. If you take the geometry chart below as an example and compare for sake of argument the 51 & 56cm frames, the effective top tube is 54cm on the 51 and 57.2cm on the 56. Just raising the saddle 5cm does not change the frame size. The effective top tube distance still stays the same. So if somebody should be riding a bike with a combined reach of say 68-70cm (effective top tube + stem length) it's going to be somewhat difficult to obtain that with the 51 because as Drew Eckhardt pointed out 140mm stems are the longest that are readily available, although in this case that reach could be achieved but there would also be a good amount of saddle to bar drop on the 51, which is not always preferred for a commuter.



Anyway, bikes are made to be adjustable, so my opinion is ride what works for you

Besides standover, frame size contributes mainly to bike handling by keeping the wheels in the right place under the rider to position the rider's center-of-gravity properly. Yes, you can mess around with stems and seatposts to make frame fit, but handling gets wonky if the stem is too long or too short, and if the saddle is too far forward or aft relative to the BB, because the rider is in the wrong place relative to the wheels.

Advertized frame sizes can be misleading too since different manufacturers and even different models by a manufacturer use different relationships between the seat tube and top tube lengths. Once upon a time, they were all "square", meaning a 58cm seat tube got you a 58cm top tube. Not any more. I own two Treks (a 56cm Portland and a 58cm 1000) and they each have a 565mm top tube, as do my 56cm Schwinn Peloton and 57cm Litespeed Classic.

Rider proportions also need to be factored in when selecting frame size. I'm all legs. If I were sized just by my inseam, I'd ride a 60cm and it would be far too big. You'll notice from above that all my bikes are sized by the top tube (565mm) for my short torso. As a consequence, all my bikes all show lots of seatpost with little setback. It doesn't look fashionable, (longer stems and more seatpost setback are fashionable) but my wheels are in the right place relative to my center-of-gravity.

I'm between sizes.

I'm about 5'5.5" and ride a 18 inch raleigh Talus MTB. It's slight bit big, but the next size down felt too small. An 18" Trek 820 is far too big, the 16" too small. Then again I'm built like a fire hydrant, short arms, thick legs and longer torso.

I stand 5'11" with a 34" inseam (standover, not pant length) so most charts put me at a 52-54cm frame, but as mentioned above so much more comes into play. My touring bike is a 54 cm (21 inch) Trek 700 frame with a slightly setback seatpost and a 90mm stem with a 30-degree upward angle (flatbar) and it fits me perfectly as a touring or general purpose commuter. I also have a trail bike based on a Trek 700 frame but with a 47 cm (18.5 inch) frame a more setback seatpost, 110 mm stem and a 1 inch rise and slight sweep to the bar. This gives me a more upright position, excellent for standing while making tight corners. Still pretty comfortable, I rode it 18 miles of mixed paved and gravel the other day with no complaint, but wouldn't be my first choice for touring and it's definately not a road bike. Makes a good cruiser/commuter though.

I've tried many road, touring, hybrids and hardtails and can say that the "ideal" size for me falls over a several cm range depending on geometry, set up, and intended riding style.

While the actual measurement of the seat tube may vary, I've found that the advertised frame sizes are don't vary all that much even from company to company. For example, a 58 cm Trek may not a seat tube that is 58 cm nor will a Specialized nor Giant nor just about any flavor that you want to choose. But the effective top tube length of a "58 cm" bike is going to be very close in all the different brands and models...if the bike is designed for a similar use.

This makes sense too, if you consider that bikes are made for a fairly narrow range of body sizes and that some of those parameters are more easily adjusted than others.

I am 6' tall and ride a 54cm frame. I have the seat and handlebars in an agressive position, but the I clear the top tube by a large margin. If I were to buy a new bike, I would buy a 58cm or 60cm frame. I am flexible, but the larger frame is much more comfortable.