I will warn you that if your husband is anything like me, then even lara bars, sweat potatoes, grapes, would be to high carb for me on a ride. THe way I figured it out, was to simple ride with my blood sugar meter.

My rule of thumb is that I try to never let my blood sugar go over 120. When not exercising, I measure the peak following a meal (45 minutes it should be under 120) and then I want it back under 100 2 hours after.

On the bike, I find I feel best with blood sugars in the 100-120 range, but I have dropped as low as 70 at the end of a century. 115 is a typical mid ride reading. But, he may have to give up a little speed. This works for moderate paced riding, but not a lot of anerobic sprinting.

ALso, realize fat is your friend. Just choose healthy fats like olive oil. As long as calories are controlled fat does not make you fat. On the flip side, high blood sugars will make and keep you fat!