I find riding fixed better for knees than riding ss. Anyhow it's the cleats that were an issue not big gears (although i was at times guilty of that) or riding fixed.
^^^was seriously considering trying that actually, would make sense if you think about it. One foot secure, the other easier to pull in and out. Track standing can >>>>>>>>>>>>>>
^^don't necessarily have to use BMX pedals, normal flat road pedals can be fitted with velcro straps
^Brilliant!