Why would the 3 smaller toes on my right foot get numb after about 8 miles of riding? It happens to a lesser extent while mountain biking (takes at least twice as long to get as numb), but happens fairly quickly when riding on the road. I just started riding a road bike and I'm concerned that this is going to be a real problem as I ride longer distances such as the upcoming MS150.

FWIW, the bike seems to fit well overall. I'm using SPD style pedals and a pair of old Lake mtb shoes that I also wear while offroading. I'm going to get new shoes this spring, but I still plan to use the same pair for road and offroad. Any ideas?

Chris