Thanks for that info, Macka! Years ago when I was a bicycle rider, I had a tandem bike in my garage. I was an active member of the Tandem Club of America forum. One of the myths about tandems was that with caliper brakes squeezing the front rims, it could be possible to get the front rim so hot that the tube would blow out. Nobody had ever had that happen, but one of our members who worked at the National Atmospheric Science and Research Center in Boulder did some computer simulations that calculated energy and heat. He found some little temperature-sensitive dots that changed colors from silver to black when they reached a designated temperature. He asked for volunteers and I stepped up. We got dots ranging in temp from 160F to 450F and put them on the rims. A buddy of mine and I took my tandem to Horsetooth Reservoir west of Ft Collins. There's a long down hill on west side that we got up to 57mph. Our scientist had calculated that we'd generate the most heat by going downhill at 60% of that speed, so we sped up to 37mph and then held that speed. Not a single dot got hot. We went to another steeper but shorter hill. Again 57mph. Again, 37mph maintained by braking, again no dot got hot. We went back up that hill, let our speed get to 57, braked hard down to 20, sped back up to 57, braked hard again, and managed to change the 180-degree dot on the front tire. So we found an even steeper hill, and let the speed build to 55, braked hard, 55, braked hard, and that time we got 220F dots to change color. Now most tandems have disc brakes and I don't think the myth has survived.