I, too, am having problems with hand numbness. I know what is causing it in my case. I am spending too much time in the drops and am gripping the bars too tightly. I just started riding in April, and only started riding on the roads three weeks ago. When I am in unfamiliar situations, I tend to stay in the drops because I feel more stable, more in control, with the lower center of gravity. I am still anxious about riding on the roads, and that is why I am spending so much time in the drops. Over time, I am starting to move up to the hoods and other postions on the 'bars, and it is helping with the hand numbness. I do note that I seem to be able to ride further each week before the numbness develops--that is progress. One good sign--in each of the previous two weeks, the numbness was worse in my right hand. I rode almost 21 miles today and had virtually no numbness in my right hand. However, by the end of the ride I had bad numbness in my left, almost to the point where I couldn't activate the muscles in my hand. I am guessing that due to the experience of the previous two weeks, I over-compensated with regard to keeping the weight off my right hand and ended up causing problems with my left.

It definitely is a work in progress...