Hi folks,
Just curious as to if anyone has attempted to quantify how much faster they are on a TT rig than a road bike for a given wattage. For example, today I did a test where I put out 326w on my TT bike to go 27.0mph whereas it took me 373w to go 27.0mph on the same stretch of road on my road bike (controlling as best as I could for all other factors). Any more data points?
Same everything else? (Wheels, tires, helmet, clothes)
Hi folks,
Just curious as to if anyone has attempted to quantify how much faster they are on a TT rig than a road bike for a given wattage. For example, today I did a test where I put out 326w on my TT bike to go 27.0mph whereas it took me 373w to go 27.0mph on the same stretch of road on my road bike (controlling as best as I could for all other factors). Any more data points?
Hmm, good question. you data would make sense, ~15% would seem reasonable difference. if you watch a lot of pro tour cycling you’ll often see leaders of the peloton/breakaway riding with their wrists resting on the handlebars (see below) trying to get more aero. It saves them watts!
What are you trying to gauge?
I don’t think you’ll learn anything from gathering data from others on this. Everyone’s positions and setups will be different, thus bestowing greater or lesser differences between their TT and road bikes.
For example there would be a huge difference between:
Case 1
Aero road bike
Deep section wheels
Narrow and aerodynamically clean bars
Fast tubes and tyres
Rider in a low position
Case 2
Large diameter round tube framed road bike
Shallow box section wheels
Wide bars, round section with lots of bar tape, lights, etc
Slow tyres and tubes
Relaxed, upright position
And the differences between tri bikes could be just as significant.
Therefore the differences in power/speed between any given tri bike and road bike owned by the same person could vary dramatically for no reason specific to the type of bike. It’s uninterpretable data and therefore pointless IMO.
That’s without even getting into any differences in clothing and variability of the test protocol.
Partly just curious and partly to know the “tipping point” where I should use a road bike vs TT bike for some technical TTs in my area.
My super crude comparison between riding my road and TT bike is around 1.5 to 2 MPH for a similar effort. This is on a course at around 20 MPH.
I’m nearly the same or a little less difference.
I don’t race my road bike so I have put zero time into maximizing aerodynamics. Therefore, the difference between my road bike and TT bike is massive. With stock wheels on both rigs at the same power there is probably a 3mph difference. I also don’t think I climb that much better on my road bike unless i’m putting out huge watts. If it’s a steady climb at reasonable power i’d say my results are similar on both bikes. Also, on steep descents the mph difference between my road bike and TT bike can be upwards of 10mph. So, even if you climb better on your road bike you’re probably giving most of it back on the descents.
CdA about 0.205-0.210 on TT bike. About 0.255 on road bike (with the same helmet, skinsuit, trispoke front; difference being bike and rear wheel). Came out to be about 2.5mph faster on TT bike at same speed.
Vs. regular road bike or road bike with clip ons? If you can achieve the same position, and you make wise equipment choices, it shouldn’t be much. If I were to set up my Felt AR intelligently I bet it wouldn’t be much slower than my Felt TT bike.
Specialized quantified this difference at 25 / 50 seconds per 40k and zero / yaw respectively.
For what its worth I’ve done the same 10 mile TT course on both my road bike and my TT bike.
Similar temperatures and wind conditions, same clothing, same time of day, the only difference being 50mm front and rear wheels on road bike, Hed6/9 on TT bike). NP of 280 for road and 279 for TT bike yielded times of 25:32 for road bike, 23:24 for TT bike
Did you have aero bars on the road bike ? Nearly all of the data I have seen has been without them on the road bike which is not a fair comparison.
your answer will vary depending on what type of road and elevation you ride on even for yourself, with all variables controlled.
It’s a pointless question. TT is faster for TT.
For what its worth I’ve done the same 10 mile TT course on both my road bike and my TT bike.
Similar temperatures and wind conditions, same clothing, same time of day, the only difference being 50mm front and rear wheels on road bike, Hed6/9 on TT bike). NP of 280 for road and 279 for TT bike yielded times of 25:32 for road bike, 23:24 for TT bike
Excellent data, thanks for sharing. The only missing point is whether making 280 watts on the TT bike took more effort than the road bike. Did you capture heart rate data, as well? Can you comment on perceived effort?
No tri bars on the road bike - just tried to get in the hoods as much as possible
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For what its worth I’ve done the same 10 mile TT course on both my road bike and my TT bike.
Similar temperatures and wind conditions, same clothing, same time of day, the only difference being 50mm front and rear wheels on road bike, Hed6/9 on TT bike). NP of 280 for road and 279 for TT bike yielded times of 25:32 for road bike, 23:24 for TT bike
Excellent data, thanks for sharing. The only missing point is whether making 280 watts on the TT bike took more effort than the road bike. Did you capture heart rate data, as well? Can you comment on perceived effort?
No heart rate data, but basically as it was a 10 mile TT you just go as hard as possible for the full duration (basically the same as a 20 minute FTP test) . So on a perceived effort scale it would be 10/10 for both !!
And on that 10 mile TT…what was the road like? Flat? rolling hills? Your test calculates out to about +2mph, which is in line with what other folks have been saying.
My TT CdA from the windtunnel is about 0.205-.210 with the full on aero setup. I have Chunged my road bike setup at about 0.240 with different helmet, skinsuit, and no shoe covers. Using the virtual aerobar position I can get within about 1.5 mph.
(Kileyay) is correct. If you can achieve the same position (the major drag issue - your body) the differences won’t be a lot.
Getting the position the same on the different geometries is tough but not as hard as you’d think.
Hi folks,
Just curious as to if anyone has attempted to quantify how much faster they are on a TT rig than a road bike for a given wattage. For example, today I did a test where I put out 326w on my TT bike to go 27.0mph whereas it took me 373w to go 27.0mph on the same stretch of road on my road bike (controlling as best as I could for all other factors). Any more data points?
Did this experiment and analysis in 2009:
http://alex-cycle.blogspot.com.au/2009/04/new-skool.html
Depending on set up differences, people will see something like 4-10 seconds per km difference between road and TT bikes.
A couple of years after this test I rode about another 7 sec/km faster than that, of which ~half was due to better TT aero.
