This year i started having a problem with my left leg going numb at mid-o.. Always happens about 5 minutes before the end of a 20 min session.. I'll start to barely notice it with not being able to pick up my foot as good to downshift.. Then it progresses to can't pick my foot up at all which is scary as hell coming off the back straight. And eventually my whole leg feels asleep. I can't figure out exactly what it could be (back, hip, etc..) Everyone that I've ridden with says my body positioning is spot on, i do have vortex rears that are raised up and back as far as they'll go.. But I've never had an issue with those on the street (although I'm not hanging off like on the track) .. I would have a P.T. I work with check it out but it's hard to exactly troubleshoot something when the only time I have those symptoms is when out on the track! Have any of you had problems with this??