A tax break on bikes would be nice for us, but I don't think it would do a lot to increase ridership. And it would do almost nothing to discourage the use of cars, IMO. Obviously it would also leave people who walk to work, SOL, along wih people who take a bus.
I would much rather see significant increases in taxes on car users.
I would want to see first, a huge graduated tax on autos and light trucks based on their gas mileage. Efficient cars should be taxed lightly, while gas guzzlers should be taxed to the tune of many thousands of dollars. The revenues should be used to implement alternative transport methods such as cycling, walking and public transport.
Secon, the tax on gas should be gradually raised until gas prices reflect the true cost of usage. Revenues from this tax shoul be usd mainly for pollution reduction and cleanup, and research dollars for cleaner forms of energy.