Road bike to TT bike. Likely time difference?

Fatamorgana

Hi.
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

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

There are lots of articles on the internet, e.g. http://www.active.com/cycling/Articles/ ... 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

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

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.

SBezza

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

Thanks.
That link too was interesting.
Thanks