My commutes have been absolutely awesome! Since I was recently diagnosed with a partially torn rotator cuff I'd been considering parking the bike, at least for the winter, and possibly resuming in the Spring (after allowing things to heal or having the recommended surgery). A few weeks ago, after an MS 150 ride in New Jersey, I thought I'd bite the bullet and take the Metro-starting a 4-5 month long bike free commute. That lasted exactly one day. Delays on the Metro and no viable cardio option had me frustrated and determined to be back on the bike the next day. Although I don't think the cycling caused my rotator tear (it was years of lifting, tennis, racketball, etc), I thought cycling certainly aggrevated it-not allowing it to heal. I now think it was more my refusal to stop the other, aforementioned activities (which I've now largely done). Since then, things have really improved and the riding's been great. Now I'm planning to ride through the winter and plan surgery in the Spring (hopefully it won't be necassary).