Rest the hamstring man. If you had an injury, it probably indicates you need to give it a bit of rest.
I actually do think bike workouts are good though. I’d go for 20-30 seconds as fast as possible with ~2 minutes in between (double the # of reps you would do of flies) to stimulate some aspects of top speed. That is a protocol similar to what Dan Pfaff did (he says) with success w/ Obadele Thompson.