writings on the bottom bracket

thomas_cho said:

Hi everyone,
I removed my cranks and bottom bracket today, and saw the following on the bottom bracket:

BB5500 (I know what this is)
68 (Does this mean English thread?)
BC 1.37 X 24
L <- 109.5 ->R

What do these numbers mean or refer to?

Thanks

68 is the width of the BB shell in mm.
1.37 x 24 is the threading (this is English thread).
109.5 is the length of the axle in mm.

thomas_cho said:

Hi everyone,
I removed my cranks and bottom bracket today, and saw the following on the bottom bracket:

BB5500 (I know what this is)
68 (Does this mean English thread?)
BC 1.37 X 24
L <- 109.5 ->R

What do these numbers mean or refer to?

Thanks

"68" means 68mm BB shell. (English thread BB shells are wither 68mm or 73mm, Italian thread BBs have a 70mm shell.)

"BC 1.37x24" is the thread pitch and such of the BB. This is english thread, 1.37" at 24 threads per inch. Italian thread is something else that I can't remember.

"109.5mm" is the spindle length. (This BB would have come from a normal road double crankset)

Thanks guys, thats helped heaps.