Power Meters / Powermeters (SRM, Powertap, Quarq, Ergomo, Vector, Stages, power2max, P2M, 4iii, InPower, Cinch)

Same at Herne hill, I still do it, as does everyone else. Safer having it there than dangling off some bit of your bike. Stupid rule.

Though having it in my back pocket seems to give bad hrm data for some reason. Quite often tells me my heart never went over 149bpm during track league.