It means that if you have 170mm cranks the BB height should be 5 mm higher, make sense?
I don't know why they persist with this archaic measure, since pedal selection and Q-factor also have a large effect on cornering clearance. Even tyre profile has a small effect. Surely it would make sense to change to an angle measurement; it would not be hard to make a scrutineering jig to check it, certainly easier than measuring BB height and crank length.
I don't know why they persist with this archaic measure, since pedal selection and Q-factor also have a large effect on cornering clearance. Even tyre profile has a small effect. Surely it would make sense to change to an angle measurement; it would not be hard to make a scrutineering jig to check it, certainly easier than measuring BB height and crank length.