Are you repleneshing your salts (ie sodium and potasium) during your exercise? This is the stuff they talk about in Powerade or Gatorade. I find a mid exercise break and eating a banana helps enourmously to preventing cramps. And for epic adventures, add a little bit of salt to your drinks, just a smidge, you shouldn't taste it much at all. Remember when you sweat, your loosing not just water, but salts too!

The second problem may be the foot bed in your shoes are flat, and the combination of this and pedalling crunches blood vessels to the front of your foot. The only way I know to avoid this is Specialized shoes, which have a contoured soul to avoid this very problem. You may not have to buy new shoues for this as you can buy the inserts from Specialized and it may enhabce the effect that could solve your problem. Check it out here...Specialized womens shoes and footbeds.

Good luck!