Many factors go into proper bike fit, but one thing is certain – you want to be able to comfortably clear the top tube with both feet flat on the ground!  The distance from the top of the top tube to the ground is the standover height of a bike.  Bike frame sizes are generally expressed as the length of the seat tube, but you can’t assume that two 56 cm bikes will have the same standover height.  A 56 cm frame measured “center-to-center” will be taller than a 56 cm frame measured “center-to-top.”  In addition to seat tube length, other variables that affect a bike’s standover height include bottom bracket drop, slope of the top tube, seat tube angle and the size of the tires.

At Speedhound, we measure frame size from the center of the bottom bracket shell to the top of the seat collar.  The ONLY ONE seat tube extends 30 mm above the top tube, which has a 3.9 degree upslope.  We also use a relatively low bottom bracket (75 mm drop), because we like what it does for stability and handling.  This all adds up to a standover height that is low for the stated frame size.  For example, our 51 cm frame has a standover height of 74.8 cm (29.4 inches), which is lower than the standover of some frames that are sold as 46 cm!  So you could say the ONLY ONE is short for its size.

Speedhound ONLY ONE Standover Height Chart

Frame Size (cm) Standover Height (cm/inches)

51                                                            74.8/29.4

54                                                            77.4/30.5

56                                                            79.2/31.2

58                                                            81.1/31.9

61                                                            83.9/33.0

These standover heights are based on a 700 X 23 tire.  For a 700 X 35 tire, add 0.7 cm (0.28 inches).