I try to bike every day, but am nowhere near the recommended pace or amount of time. I keep plugging away anyhow. I use an stationary recumbent bike (best with Ska reggae type music from free Pandora internet radio!), but am having difficulty maintaining speed due to sciatic pain in hip, plus a tendency to get winded quickly and lose energy. My tremor does sometimes worsen while biking fast, but goes away when I stop. I figure it's worth it, because some exercise should be good for general health reasons, even if not enough to be effective for possibly controlling PD symptoms or progression.