I would commute by bicycle, even if it wasn't economically rational. I think I must be into bicycle commuting for different reasons that the OP.

I haven't read all responses, but surely there are others that don't need to rationalize bicycle use by these criteria.

I'm not saying it isn't useful to compile reasons for those who only calculate worth in $ (and cycling clearly wins in this area) but it's not something that I need to split off from the holistic benefits. Bike commuting stands squarely on its own as a comprehensively smart thing to do.

Incedentally, this guy, with a penchant for cost/benefit , did such a thing when he decided to become a full-time bike commuter.