I thought the 13-19 was the rim without the hook for an aramid beaded tire and the 13-20 was the slightly wider redesign with the hook bead for folding tires. I weighted 145-155 lbs in the 70's 80's 90's and I still use these rims regularly. I have dented them but that is due to underinflation and a narrow tire. I have never had a problem with these with a wider tire and proper pressure. These were the lightest 630-622 mm clincher rim that I am familiar with. Brian Blum in Berkeley