i assume you don't have weights, either, for something like a standing dead-lift.
maybe find a cord that stretches, attach one end to your ankle, the other end to whatever will allow you to flex (heel to butt) the hams. at some point, as far as really addressing the situation and getting the hamstrings stronger, you'll need weights; otherwise you're quickly into the diminishing returns area.
also, resume jogging when you're able. just as biking will focus on the quads(front of the leg), so does jogging work and strengthen the hamstrings. and stretch those things after the jog. treat this as long-term; it takes longer than you'd think (based on how you feel) to truly get the hams back to optimal strength and balance.
edit: also, if you have a partner available, you can have them supply resistance with their hands, varying the degree and duration of pressure while you do the flexing motion.
<FONT COLOR="#800080" SIZE="1">[ October 26, 2001 01:03 PM: Message edited 1 time, by ryan ]</font>