I have cut a hole in the front of a pair of lycra shorts before to havea wank with them on, and also cut a hole in the back of a pair of tight levi jeans so i can fuck myself with a dildo while spunking inside my jeans...mmm
Have you seen the porno Les Grimpeurs? It's got guys going at it in cycling kits. Most of them remove it after a bit, like in usual pron, but then the last part has a guy who just pull his bib down far enough while wearing his jersey still. Super hot.