As weightweenies seem ask the question relatively often on weight training and studies on it's effects for cyclists, I thought this article was interesting - http://www.drmirkin.com/fitness/weight_training_cyclists.html
A study from Cowan University in Joondalup, Australia shows that adding resistance leg weight training does not help competitive bicycle racers to race faster (1).
The cyclists were divided into two groups: one that continued their bicycling training, while the other group did the same cycling training but added a six-week undulating, periodized resistance training program (3/wk). Before and after the six-week training period, the cyclists completed a maximal graded exercise test, a 30-km dynamic cycling test with three intermittent 250-m and 1-km sprints, and a 1 repetition maximum (1RM) squat test for the assessment of lower-limb strength. The weight lifters became stronger and improved their one- repetition maximum squat, but they failed to improve any aspect of cycling. Surprisingly, their final sprint in their 1- km time trials were significantly slower than their previous times.
Cycling is a power sport. Those with the strongest legs are the fastest sprinters. Yet lifting weights made them slower sprinters. Lifting weights with their legs left them too sore to train most intensely on their more intense cycling days, and the faster you ride on your intense days in training, the faster you usually ride in races. Further studies in the future may change the way we think now, but most research show that resistance leg training with weights does not help experienced and well trained, long distance cyclists to race faster.
On the other hand, strength training may help some runners run faster. Research shows that strengthening the leg muscles of runners allows them to run faster because they stay closer to the ground and do not waste energy by bobbing up and down as much with each stride (2,3,4).
1. Journal of Strength and Conditioning Research, November 2009, 23(8):2280-6.
2. Journal of Strength and Conditioning Research, 2006;20(4):947-954.
3. European Journal of Applied Physiology, 2003;89:1-7.
4. Journal of Strength and Conditioning Research, 2003;17(1):60-67).