Craig,

I don't doubt that under normal exertion usage, that vest works like a charm. My main problem with all of them has been that in 85F-90+F weather, when I am riding hard, I will heat one of those vests from 64F to 85-90F in about 5-10 minutes, and then instead of cooling, it begins to function as a heat trap and makes me hotter instead of cooler. Since break points on most rides are 10-15 miles apart (~40-60 minutes riding), I would get about 10 minutes of benefit and 30-50 minutes of harm out of a vest before I could change out the inserts.

If I instead start with the inserts cooled to 20-30F, then I can get longer usage before they become ineffective, but then I have to have a fridge or freezer to keep replacements that cold. Now if I could just get a little mini fridge powered by the bike wheel and mounted on a rack behind the seat, I would be set...