Road bike to TT bike. Likely time difference?

Fatamorgana Posts: 257
edited May 2013 in Amateur race
I am wondering: if say rider "A", for argument's sake, clocks 30 mins on a 10 mile TT on a 23lb, bog standard alu' road bike, what is the likely time on a good TT bike with aero helmet?
I'm being hypothetical as we're speculating what a friend will / might manage given his likely (?) change in a TT bike he's borrowing.


  • imposter2.0
    imposter2.0 Posts: 12,028
    if 'your friend' is borrowing the bike, then it is unlikely to be set up for him correctly. In that sense it might even make him slower.
  • ju5t1n
    ju5t1n Posts: 2,028
    There are lots of articles on the internet, e.g. ... its?page=2

    On our club’s 20km TT course I am consistently one minute quicker if I use my clip on aero bars
  • GiantMike
    GiantMike Posts: 3,139
    There are 2 conflicting factors. A more aero position will make your 'friend' faster for the same power. But, a more aero position may affect the power your 'friend' can produce.
  • Tom Butcher
    Tom Butcher Posts: 3,830
    I reckon a minute plus if they've done a bit of practice on it or else the TT bike is poorly set up/doesn't fit. On our 12.5 miler clip ons and a bit of fettling the position were consistently worth a minute.

    it's a hard life if you don't weaken.
  • SBezza
    SBezza Posts: 2,173
    There are too many variables really to give a certain time improvement, you will certainly get an aero improvement, but the change of position might affect power output, so likely take away alot of those gains. You should be faster without a doubt, but it might only be a little bit considering not being used to the TT bike position.

    Aero helmet will help with the aero gains, if fitted properly and it sits correctly in the TT position, have it with the tail in the air, and it might end up being slower. One of the best gains is getting rid of shorts and jersey and wearing a skinsuit instead.
  • Fatamorgana
    Fatamorgana Posts: 257
    That link too was interesting.