I would like to try the Lowes Motor Speedway TT series and at the same time do a new bike build (a TT bike), So I thought I would ask here. BTW, these questions will not be about components, just frame sizing.

I have used and seen most of the online fit calculators for road bikes, but I have never seen one for TT bikes. I am not even sure where to start. Is the frame sizing comparable? Do I use the same top tube measurement that I feel comfortable with on my road bike? I see that seat tube angles range from 75 to 78 degress and probably more. What are the advantages/disadvantages when your at either extreme of the range? I have seen and read about what you should look like for riding position, and I think I am flexible enough for an old fat guy to get there, just need some guidence.

Currently I ride a 56/57cm frame with a TT of 55-56cm and a stem length of 110-100mm. I use either 172.5 or 175mm cranks. If anyone needs more info just ask.

Thanks in advance.