66GI is the golden ratio for me in London. So much easier to drop people when the lights change and they're mashing away trying to get up to speed. Much easier to skid control your bike too, or at least I find it that way.
Whack on 70+ as soon as you get out of town though.
This. I have that ratio and legs like Gregory Bauge
This. I have that ratio and legs like Gregory Bauge