What's the rules on bikes for the TT's?
Have a look on the Cycling Time Trials (the governing body) website. All will be revealed!
All the history, rules and regulations (including bikes), clubs, courses, events, records, past champions etc. etc.
Hours of interesting reading
Seriously, so long as the bike is road legal then it should generally be OK (but no 'superman' or 'tuck' positions). CTT does not have to comply with UCI regulations. It's the clothing aspect which is slightly more restrictive(eg - no sleeveless tops!) Have a look at the 'Gallery' photos of riders competing in events.
Today is the yesterday of tomorrow.