I found this in the excellent column discussing cramps for another thread:
I'm 50 years old, 5'8" 175lbs. I ride mostly on the road. I've been getting hot feet after about 20 miles into my training rides. The hotness is mainly on the balls of my feet. Any help on this matter will be greatly appreciated.
Steve Hogg replies:
Is this a recent problem or one of some standing? If it is recent, what has changed at that time? Have you changed shoes, cleats or pedal systems in the recent past?
For instance, I am aware of people who have purchased snugly fitting shoes in winter, only to have them be too tight in summer with the onset of warmer weather and consequent slight swelling of the feet that can accompany higher temperatures for some people.
Assuming none of the above is applicable, the other causes of your problems can be:
1. Shoe too tight across the forefoot or too short in length causing compression of the metatarsal joints and pressure on the nerve junctions in that area.
2. Cleat position too far forward. Make sure that if you mark the centre of the ball of the foot on your shoe, that the mark is slightly in front of the pedal axle with foot forward and crankarm horizontal.
3. Shoe sole that is too stiff or paradoxically, far too flexible. Stiffer is generally better for cycling shoe soles, but there is such a thing as too stiff a sole for some people.
4. Foot misalignment. This is common but usually only affects people in the way you describe, in my experience, if the cleat position in also less than optimal.
I suggest that you work through the above points 1 - 4 if you have had the shoes and pedal system unchanged for some time. If not and something has changed at a roughly similar time to the onset of your problem, get back to me and let me know what changed and so on and I should be able to refine the advice given."