Question re: frame size/SO height
 

Can someone please answer this question. I am looking at a couple of bikes online that both have the same size wheels. One is a 21.5" frame; the other a 23" frame. Both say the stand over height is 32". How can that be? BB height difference? The 21.5" bike does have larger tires, but by less than a quarter inch. I contacted the sellers and confirmed the measurement as being the exact measurement from ground to top of cross bar. Both have level horizontal top bars. Can the top bars be placed in a lower position on some frames?

bottom bracket height and measurement of frame are two places where the height could vary

Quite commonly bikes are not measured properly. Sounds like this is an ebay type situation, rather than a catalog one. Cats are really bad.

Sloping top tube to some degree would make sense, even if they look relatively level. Another possibility is that the larger frame is not it's full size just because it is called a 23 doesn't mean it is. There can be a 1.5 difference in BB heights. Normally there is a preferred height for a given service, but I have seen that much variation. I remember this one aluminum touring frame that was so high it could have run 26" wheels as well as 700c with a few tweaks.

Also, if the frame is measured from the crank center to the top of the seat tube, the standover height would be lower if the intersection of the top tube and the seat tube is significantly below the top of the seat tube.

Case in point; both of these frames are sized as 24" from the crank center to the top of the seat tube, but the Super Sport has a significantly lower standover height (~1"):

'72 Paramount:

http://i32.photobucket.com/albums/d7...eatTubeTop.jpg

'73 Super Sport:

http://i32.photobucket.com/albums/d7...eatTubeTop.jpg

Thanks for the replies. I think that answers my question. Differences in how they measure the frame, more or less seat tube extending above top tube, BB height, etc.

One thing to focus on is how you could get them to give you the info you want. If the people you are dealing with have tape measures and access to the bikes, you should be able to come up with some pointed questions that would allow you to get real info.