Sizing:

Small :
- 15"-18" mountain bikes, or larger Aluminum frames
- Some 4 bar full suspension
- 52-56cm road / cross bikes
- Top length 17", Height 4"

Medium:
- 17"-20" Mountain frames
- 55-58cm road & cross bikes
- Top length 19.5", Height 4.5", 1" of height at head tube.

Large:
- 20"+ steel mtn frames
- 56cm- 62cm road & touring bikes
- Top length 21", height 6", 1.5" of length at the head tube.