Hanginon wrote:
In the GCN YouTube video they reference the very low Q factor on Bigham's bike. Obree's knees were so close together (very narrow BB) that he had to eliminate the top tube on the frame, and mount the chain stays high up on the seat tube to give clearance for the cranks.
As I recall they said his bike was 130-something mm, which isn't all that narrow (my TT bike is in that range), but road norm is ~150. Narrow Q has been known to usually improve CdA since at least Obree's time. Lance experimented with it but didn't like it. The cheap way to achieve this is with old Dura Ace square taper cranks.
Narrow feels better to me, but there are practical limits. On my current frame I needed to go from a 103 to 107mm so the crank arms wouldn't hit the frame. Chainstay clearance with your feet can be another limiter if you pedal heels-in at all.