Well for what it's worth I rode
Herne Hill Monday Comp track league and TimeTrials on 86", on my winter club run commute bike I used only a 62", all on 165mm cranks.
The 62" was fine for me as I like to spin gears plus ride in the surrey hills, although I used the 'Cyclo' made sprockets, as it was only those I could get at the time as large as 21t, they were in fairness not the highest quality, neither very round making chain tension a bit of a lottery, plus they could strip the hub occasionally as the threads on some were not exactly that accurate either! Back then the sprockets from the higher quality manufacturers were not as readily available as they are now.
I rode fixed for about twenty years, I have a bad back and a bit of a dodgy
ticker now, which didn't seem to like me spinning down hills, I would get a pain down my arm especially on a long quick descent which scared me a bit so I reverted to gears; a real shame as I always loved riding fixed.
Paul_Smithwww.bikeplus.co.uk