I am having a problem with a hot spot on the underside of my left big toe. I'm using a Sidi Dominator 5 for both MTB and road at the moment, and no real problems in the cleat area, but on longer rides the underside of the left big toe, the pad of the toe, goes numb. I think maybe I'm clenching it or something. In any case, does anyone have suggestions for fixing this? I'm open to anything at this point.

Cleat placement, by the way, is about two-thirds of the way back. If you figure the cleat has about a 24mm range, it's about 8mm from the back, 16 back from the front. The shoes are size 46 narrow; FYI I have a long arch, that sizes about a 46.5, but short stubby toes that leave a decent amount of room in the front, and if I could get the shoes narrower I would. I think they're about a B width, and while that's a good match on my right my left is more like an A.

Stop clenching.

Seriously.

I've had problems with my big toe going numb in the past. I don't know about you, but my big toe is friggin huge! Because of this it takes a good brunt of the pressure when I am pedaling and has a tendency to go numb. I also use Sidi shoes, I'm on the Energy and Enegy HT's. What I have found that has helped more then anything is switching my insoles. I originally replaced the Sidi insole with some old New Balance insoles and that helped a bit. I then replaced those insoles with some Specialized BG insoles and again that helped. What even improved it further was adding one Specialized BG shim under the Specialized insole. The shim allowed the ball of my foot to sit better in the shoe and take more of the pressure that it should. The Specialized insoles also have longitudinal arch & metatarsal button support which is suppose to help with numbness issues.

When adjusting cleats don't forget the side to side adjustment. I was having hot spot issues and found out that I had to adjust my foot closer to the spindle.