I propose that cycling gear be sales tax free. Though in my case that would mean I would buy more and ride the same. Probably a universl result so I agree with the previous poster who said it wouldn't encourage people to ride more for transportation.
I believe the biggest reasons for not riding have been shown to be traffic and weather. Lower taxes wouldn't mitigate either. A 1000% gas tax might reduce traffic but it would be hard to get elected on that platform.