Believe it or not...I don't know (remember) what size my HH100 is. How would I find out? I think it's 23.5... BUT...I want to measure it against some other frames that are in the house. I am trying to get a singlespeed that fits similar to my HH... One has a taller headtube, another longer seattube. It seems that one frame is smaller than the HH, while the other is longer. Hmmmmm....which one to build up. Anyway, still want to know how to measure the TT on the HH, given that it is sloped. Thanks. Alan.