Road bike vs Tri bike speed

All things being equal how much faster pace could someone average on a tri bike than a road bike?

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My ‘easy’ rides on a road bike will be 19mph ish. My ‘easy’ rides on a TT bike are about 21mph ish.


Some bit faster, or not at all

Depends on your positions (difference between road and TT), ability to put out power in TT position, comfort in TT position (can you actually hold it for any reasonable length of time)

Friend of mine went slower on a TT bike. could never adapt to the position, and his position wasnt that great anyway

Personally I am about 3-4kph faster average over a 300w-ish effort


At a somewhat recent 8 mile, double turn around TT event I raced both bikes. My road bike was with 50mm wheels and no TT helmet. The same pedal PM was used for both bikes. Previously I’ve gone faster on the TT bike but that day had some decent crosswinds.


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@Majoeric so without the crosswinds with conditions being equal would you say about 2 mph faster on your TT bike?

@ErickVH my tempo rides are around 21-22 depending on the winds and how I’m feeling. I’m very aggressive in my riding position so I don’t think the aero position would bother me that much. Would it be safe to assume 23-24 is achievable over the same wattage output?

I’m about 2 kph faster on my road bike with clip-on aero bar extension than on the hoods. It’s taken me a few months to get my aerobar FTP to within about 5W of my upright FTP.

I could probably do better than this on a dedicated TT bike with my position more optimized for the aero position.

2mph is a push… I would assume 1.5mph is realistic.

I consider myself somewhat dialed in on my position on both bikes.

The TT bike is a SpeedConcept and the Road is a Aeroad. Both had same Corsa tires.


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1 to 1.5 mph for me.

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Nope. Just go ride your bike, optimize it as much as you can.

Its going to also depend a LOT on the roads and route in the real world rather than a perfect situation.

Can you actually hold the aero position on the roads with the traffic, junctions, road conditions etc? Around here you wouldnt last 5 mins riding in a tuck except on main roads, simply due to the horrendous state of the tarmac, the type of narrown country roads etc. Then you have to content with high volumes of traffic etc.

All things being equal I think the estimates about of around 1.5mph are probably fair if you have a good aero position on the TT bike and have enough time on it that you dont suffer the huge power drop many people do initially.

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As already said, it depends on equipment, position and ability to ride this position with comfort and power.
For me the difference was huge. I rode 37kph during my last IM and my roadbike average is more like 30kph.
But the tri bike speed was on a race course and perfect conditions and the roadbike average is on roads with traffic.

Disc wheel should be around 0,5kph faster, helmet, suit, position, aero bottles, tires, etc are normaly different on a tri bike, too and make a huge difference.

But if you only compare the tri bike frame with an (aero) road bike frame, there is probably almost no difference at all.

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A friend of mine was similar on his aerobike with clip ons he was faster than on a dedicated TT bike.

As to the original question I have to go back 8 years on our generally up hill sporting club course on a road bike (so hardly comparable) but for 10 miles its circa 2mins 15 (2mph ) slower.

2mph for me but it’s not just the bike. If I ride my TT bike (disc and 90mm front) in a TT I use my Giro aerohead, Castelli fast feet overshoes, a nopinz flow skinsuit and aero gloves. If I use a road bike (Campagnolo Erus 1450g 28mm climbing wheels) I usually use it for training so often ride out to the race so it’s bib shorts, no overshoes, standard cycling mits, castelli jersey (tight but not a skin suit with some spares in the back!)…I do use Conti GP5000 25mm tyres with latex tubes on both my TT and summer road bike :grinning:

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With equal fitting clothing, wheel and tire setups and very aggressive positions on each, I am looking at about a 3-4 km/h difference between road and tt bike ( 2-2.5 mph )

Only real difference in my setup is that on the TT bike i wear a giro aerohead vs a giro vanquish ( aero road helmet ) and the rest is down to position on the bike.


Of course, this is also dependent on having a proper, good position on the bike, if you don’t get a great tt bike fit, then your aerodynamics will suffer, as will your comfort, your ability to produce power, and your ability to hold the position, all of which are important.