A variation on pigeon pose, this is Refers version, with the bike as stabilizing prop. The pose works the piriformis muscle and strengthens the upper legs (and the core, if you use mula bandha). Tuck your tailbone just a bit here. Breathe in this pose, and come out of it when shaking sets in. Be aware of strain in your knees and counteract it by engaging leg muscles to bone. Rise up a bit if they still twinge.