I’ve been searching for the root for the term Q factor to no avail. There is a weak explanation on the Rivendell site alluding to Q for quack as in duck-like walking with a widened “tread”. I don’t believe it. Anyone out there that can help?
Q factor as it is used in anatomy refers to the quadriceps angle the creates the genu valgus (outward bend) of the knee when compared to the tibia…
your shin goes straight up and down (almost) and your thigh points outward from your midline… voila Q angle…
How this got to be used for biking I have no idea but my guess is that there is a optimal distance (for each person) to have their foot away from the BB, which would depend on that person’s Q angle among other things.
hope this helps
I think Grant Peterson (of Rivendell) came up with the term “Q Factor” when he was working for Bridgestone bikes in the 80s/90s. “Quack as in duck-like walking” is probably the best explanation you’re going to get. Grant has a lot of notions of how a bike should be built, but none of them are very scientific. He bases most of his ideas on comfort, aesthetics, and usability.