2007-06-17 03:40:14 · 4 answers · asked by cowboy (1) 1 in Sports ➔ Cycling
Traditionally, from the bottom bracket to the place where the top tube intersects the seat tube. Road bikes usually are measured in cm, while mountain bikes in inches.
I dunno on BMX or hybrids.
On most mountain full suspension bikes, they use S,M,L,XL to denote size, since the geometry or shape of the frame doesn't lent itself too much for just measuring them as a hardtail.
2007-06-17 05:55:02 · answer #1 · answered by Roberto 7 · 0⤊ 0⤋
By the diameter of the rim and by the top tube frame length.
For example: you have a 20" inch BMX in Pro size. Which means you have 20 inch tyres and a top tube (TT) length of 20 to 21.5 inches.
You can have a Junior BMX which means it will have 20 inch tyres (which are actually closer to 21 inches) which would usually have a 1 3/8 inch or 1 1/8 inch thickness. And the top tube length will be about 18 inches long.
Its not as confusing as it seems. I promise.
2007-06-17 04:33:26 · answer #2 · answered by Anonymous · 0⤊ 0⤋
the size of the tires a 20 inch bike has 20 inch tires
2007-06-17 03:47:51 · answer #3 · answered by upforitupforitupforitupforitru 3 · 0⤊ 0⤋
measured by the Frame.
2007-06-17 04:28:34 · answer #4 · answered by Jazz DNA 3 · 0⤊ 0⤋