Im tryin to figure out some seemingly simple things about my Cannondale Black Lightning, Im just really dumb and this is my first road bike so hopefully someone could help me out with figuring out what the Size(cm) and Standover Height and stuff like that might be.
click here to view the bike: http://s19.photobucket.com/albums/b1...t=HPIM9416.jpg
If you are trying to sell the bike, I would suggest supplying the following information in your ad:
(i) the length of the seat tube,
(ii) the length of the top tube, which is what I think the size of a bike is, and
(iii) the standover height, which is the distance from the top of the top tube to the ground when the bike is upright.
You can measure these things yourself with a tape measure, and if you want, you can multiply the length (in inches) by 2.54 to get the length in centimeters.
Now that I read Sheldon's page more carefully, I see that he suggests measurement (i) is the size of the bike. Hmmmm....
If you're planning to buy a new bike, don't forget to check out the introductory threads at the top of the various forums (Road Cycling, Commuting, MTB, etc).
Generally, when you see a single number listed as a frame's "size" that number refers to the length of the seat tube . A further complication is that nobody knows how to measure a bicycle's seat tube any more. Even leaving the inches/centimeters question out of things, there is the question of where the seat tube ends:
The old standard system was to measure from the center of the bottom bracket to the very top of the seat tube.
Some manufacturers have decided that this is too easy, so now many bikes are measured instead to the intersection of the centerline of the top tube with the centerline of the seat tube.
Some other bikes that have seat tubes that protrude farther than normal above the top tube measure as if they were measuring to the to the top of a seat tube with normal protrusion.
Some bikes are measured to the top edge of the top tube, even though the seat tube protrudes higher up.
Some bikes with slanting top tubes are measured as if there were a level top tube, they use the length that the seat tube would be if it was as high as the head tube.
Anarchy reigns; I know of one bicycle line that made a running change in the middle of the year. You could have two bikes of the same make, model, year and nominal size, but one was 2 cm larger than the other! The only way to know was to measure them. An additional complication is that the height of the bottom bracket varies over a considerable range, typically anywhere from 10.5" to 13"! Thus even frames that use the same system for figuring the top of the seat tube may have widely disparate stand-over heights.