Time trial bikes – how much faster?

On a slight detour to my normal commute home, I got mixed up in a local 10k time trial. A rider passed me just before a short climb, I then overtook him on the climb, but then a minute or so later he came steaming past me. I was sat at about 34kph (flat road, road bike) and he must have been doing 38kph or so. He pulled a bit of a gap, and then I tried to catch him but couldn’t. Are TT bikes that much faster? (I know it could have been that he was fitter, but I overtook him on the climb, so I figured that like for like, I could have been quicker).
This isn’t a gloat, just a genuine question. I always imagine that a TT bike could shave a few seconds or tens of seconds off, but 10% quicker on the flat – that’s quite some advantage.

And before the pedants get in, yes, I gave him lots of space, did not draft him, didn’t bare my arse or put him off – I can’t think of a reason he would have not wanted me there (I may even have helped him by being someone he could chase down).

he’s got to do 10k at the same speed, so probably not up for hill sprints – better to keep the same output throughout i believe..

probably bar position more than the bike specifically.

He may well have had a plan for his ride hence the pace he rode the hill. So he might be a fair bit fitter.

Saying that i would imagin that a decnt TT bike with all the gear and riding position would be close to 10% faster, especially as your speed rises past 25mph.

Just having a narrow frontal area and a skin suit makes a huge difference.
Wheels and frame obviously help, but your body is the main drag factor.
Also, aero dynamics play a part as soon as you start moving and only plays a bigger factor the faster you go.
A TT helmet is 4x’s more aero than a standard vented road helmet.

It also sounds like you just got passed by a standard club rider because if you got passed by one off the fast boys, you would’ve had no hope in keeping up as they tend to do around 30-35mph+ on the flats!

TT bikes are generally heavier due to focusing more on aerodynamics. another reason to be not as quick uphill.

probably bar position more than the bike specifically.

Nahhhhhhhhh

Look at Obre’s bikes, he did TT’s on ‘normal’ drops, but with a reallyt tall stem, and the bars reversed. The flat back comes from the seat angle being 75deg+ not the more usual 73. The steeper angle lets you lean forewards by the same ammount, and the forearm rests aren’t generaly any lower than the normal bars tops, often considerably higher.

Obree? Really? The man was obsessed with being different just because he could be, which is fair enough…but I’d respond by suggesting one examines Chris Boardman and Abraham Olano’s position on the bike.

The man was obsessed with being different just because he could be,

Maybe, but consider the superman position was his and is regarded as about a fast a position as you can get, hence the UCI banning it….

A website did an article/test on this topic which has been linked to here, it’s better than the guesswork above – the bike weight will have had minimal effect for starters.

Bike Radar did an article looking at the power savings from a TT bike, aero bars, and a TT helmet, which may be what Al is referring to. All added up to pretty significant savings.

Fair point MrMo, I recall that the superman position was Obree’s originally but Chris Boardman seemed to make better use of it (in 1996 for example), furthermore Obree’s hour record (1993) was set in some bizarre tucked position with his hands brought in close to his chest.

Cermaic bearings in the BB and hubs will give someone a 1m advantage over every 100m for the same power output – a lot of small saving soon add up.

I bet he had his tyres pumped up pretty hard as well.

Obree had to go to the tucked position because the UCI banned the Superman position. At any sort of speed on the flat nearly all your power is going into pushing air out of the way, every little helps 🙂

Most TTers aim for constant power over the entire duration – hence they’ll be slower for hills. Aero bars and good position (flat back) make the biggest difference. After that its aero helmet, deep section front rim, disc rear wheel, aero frame.

Good point Mike, I might be wrong though, wasn’t the superman position banned by the UCI after Boardman’s 1996 record?

Our club does an ‘Athletes 10’ every year I rode back to back 10’s and found that the tt bike (disc, deep section, skinsuit and aero helmet) was 90secs quicker than a road bike over a fairly lumpy 10 miles, standard wheels, standard jersey, standard helmet etc.

Obv depends on the rider and there will be some slippage due to riding back to back 10’s

not even a pure power thing necessarily.

if you’ve ever ridden a TT bike with a proper TT position you’ll know they are a total dog to ride uphill on some times.

ridden on the flat they are SIGNIFICANTLY faster. couldn;t tell you in terms of definate percentages, but anecodtotally i have ridden tt bikes that are too small for me, and still averaged 2-3mph faster over given sections.

once they are rolling they seem to thunder along.

Obree’s position was all about getting his body aero and not wasting energy supporting his upper body when it was essentially adding nothing to his performance. His ‘arms tucked under him’ position came about so he could rest his body down on his arms and get a flat back. The superman came about after the other was banned (it still meant his arms weren’t supporting his upper body weight) and Boardman copied it to set his hour record.

As for TT bikes, the bike itself won’t be much faster it’s that the overall package of bike and bars allows the ride to reduce their frontal area. 10% is on the high side though, most test stuff I’ve seen is more 3-6% depending on speed and conditions. I guess on a flat section going 30mph+ it could be that big a difference though (vs someone just riding on the hoods/drops of a normal bike).

my favourite article on this subject
http://www.bikeradar.com/gear/article/how-aero-is-aero-19273/%5B/url%5D

That was the article I was thinking of, pretty massive savings between their ‘basic’ and their ‘full aero’ set up.

And a newer test, “Aero position isn’t everything”.[/url]
After reading the above, i now use the Mantis position and can see/feel how it is faster.
Now i just need to get fitter!

if you’ve ever ridden a TT bike with a proper TT position you’ll know they are a total dog to ride uphill on some times

This ^^^

I once started a 25TT behind one of the good guys (Carlos Riise ).
The speed he went up the road ( once he got the big gear turning )
made me want to go back to the car. 😯