Here's what I believe this means:

It doesn't mean that you get $20/mo. for riding a bicycle.  It means that *if* your employer gives you $20/mo. for riding a bike, then you don't have to pay tax on that $20.  Whoo-hoo.

Yeah, not incredibly exciting.  But drivers have already enjoyed being able to get a $215/mo. tax-free benefit for parking, or $110/mo. for using transit or vanpools.  So at least cyclists now get something, instead of nothing.

Personally, I'd like to see the tax-free benefit for parking disappear.  Why are we subsidizing driving?