I've recently found my way back to TT riding after an 11 year gap. Initial attempts have been on the slow side of respectable, but I seem to be able to comfortably spin at 90-100 rpm and stay on the tri-bars for the duration of a club 10. I was commenting to a friend last night that it might be time to dust off my disc wheel and give that a go to trim off a few seconds. He replied that to get any advantage from a disc, you need to be exceeding 25mph. Has anybody else come across this figure? It's a new one on me.
