Just another note of information.
I use to ride my mtn. bike into the springs up PCT from the Majove River Dam. I found out later, after a scolding from a USFS crew who was working at the dam as I was riding back, that the trail is NO VEHICLES ALLOWED. I thought it was just motorcycles and 4-wheelers they didn't allow. But it means no Mtn. Bikes as well.
So... if you want to bike, ride it on any of the dirt roads to get you to the hiking trails, but I would suggest not riding on any of the trails down to the springs.
Some areas on the trails are pretty sandy and would cause you some grief anyway. It was fun while it lasted.