I use a sledge harness(designed for pulling uk design) and drag a large truck tire behind me using rope/chains on the pavement with my single speed for interval bursts of pure animal aggression. Man, i am telling you, it can be painful! It also seems to help develop upper body explosiveness, all useful for a 0-8 mph(from stop to full throttle) After about 10 min of this you are ready to burst into flames. A wonderful all out session in about 30 min! When it is wet it glides a little easier, but still have constant resistance. I like to do a 30 min sprint set, all done at 90% maximum heart rate. Hills are almost impossible with this, best done on flats. Session speeds range from 2mph-15.
The advantages of super slow mo training:
less risk of injury to joints
high pulse rate