If you can walk on it you can ride but if it's weak you might want to tape it up with some good athletic tape (don't forget the prewrap unless you like pain). You don't say if it's swollen, bruised or painful.
For an ankle injury, the quickest way to rehab it is to ice the heck out of it, at least 15 minutes 3 times a day. I prefer to stick my foot into a bucket of ice water (really feels good for the first 3 minutes until it's numb :p really, those are tears of JOY!).
Once the swelling is gone then do the 15 minutes of ice followed by 15 minutes of heat 3 times a day.
If it doesn't hurt WALK ON IT! If it is weak be very careful when walking on uneven surfaces so you don't roll it again. If it hurts slightly, WALK ON IT CAREFULLY try very hard not to limp. If it hurts too much to walk on, don't!
I sprained my ankle once (out of several times) really bad the evening before I was flying from AZ to FL for a beach volleyball tournament. I iced the heck out of it for the first two days there (before the tournament) and by taping it up I was able to play (this was Florida sand NOT California sand don't think it would have been strong enough for CA sand). No permanent damage and we did pretty well in the tournament (but that was over 15 years ago and now I don't heal so quick plus I wasn't about to waste my trip to FL from AZ).
Some good ankle strengthening/flexibility work is to write the alphabet in the air with your foot - cursive really gives you a work out. ;)