I've been using clipless pedals for about 800 miles now. All the unclipping and clipping is not the problem. I just don't feel very efficient in the upstroke of the pedal. It tires me out very quckily and I only use it in very short bursts (ie upto 10 strokes) like when moving off from a standstill, and when i start struggling with an uphill. But so few strokes and it tires me out, and the back of my leg instantly feels tight even with loads of stretching. Now i've covered 800 miles witht these pedals and I'm still having trouble getting any sort of rhythm going. I only use upstroke about 1% of the time. So any tips, on how to improve my technique would be appreciated.