Save a pint, pace yourself...
It is my experience that if you ride really really hard, crankin with all yer might, you can out run the bastards long enough to stop and catch yer breath. You might even get a sip in on the ole camelbak before they catch up. BUT by the time you realize the feast has begun, and get yourself back up to escape speed, you've already lost a considerable volume of blood..... So last summer i tried a new idea... not exactly the easiest method, but it works and could possible solve the problem for ever... The trick is to never give them even a taste. When you're ready to start riding, mount your ride (hehe) inside the protection of your front screen door. Ride a monster wheelie right through the screen and off the porch. Then, make straight for the trail you intend to ride. Once you get there, maintain a constant forward motion preferably as fast as you can ride. Continue at this pace for the duration of the ride, making sure to NEVER stop for ANY reason. Gotta go #1... no need to dismount.. just wait for that long downhill stretch and let 'er rip like a good old-fashioned stage-racer. Gotta go #2.. well... should thoughta that before crashing through the screen door. Again, the trick is to never give 'em a taste of fresh blood. So keep riding as fast as you can. If you absolutely have to stop before you get back and board up the front door, make sure you are completely submerged in either water, or mud. Remember, the trick is to prevent the little bastards from ever getting a taste.
If we all do this for long enough, natural selection will get rid of all the nasties that have acquired a taste for bikerblood, and no one will have to ever use any kind of government-regulated petrochemical repellent again! So beef up that metabolism, strengthen that heart, and give those bloodthirsty bastards a run for it!!
Also, they like darker colors (i heard 'em whisperin). So wear a white t-shirt and they will be less attracted to you, AND you can have that cool mud-roost up yer back at the end of the ride ;p