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New TT bike data from Tour Mag
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They've written up the test in the september issue and posted the yaw graphs here http://www.tour-magazin.de/...-im-test/a45071.html

As usual I have digitised the data and compiled a comparison graph

As with every comparison test of the past 5 years, the winner is Cervelo. BMC have done extremely well with the new TM01 (but only with the flat bar, the V config comes with a marked penalty) to get close.
The canyon is pretty much the same in TT and Tri configs.
IA is where we'd expect from other testing.

P5-Three beats P5X but from the pics this is a bare bike vs one with luggage. Not surprising given the strictures placed on the P5 in the Cervelo testing. Kileys testing also based on carrying hydration.

We can't get much useful from the different wheels tested as the tyres were different - the Profile 78s had 25mm Schwalbe vs 808s with GP4kII 23 on the front and GPTT 25 on the rear. Likewise the Mavics using their own tyres.

To give context I've used the model I constructed for Kileys testing - Chattanooga 70.3 2017 with his parameters (ride time 2.16.32). You can look at his report for more info and to compare to the time differentials he found.

Before I get into that it's important to note that Tour use pedalling legs but no torso/arms. Which means that the impact of the rider on the bar performance (which can be significant) is not factored. Even small differences like the extension rise and armrest size add up - the BMC and Felt DA have chunky Profile F40 armrests, the Canyon ones are quite large too - vs IA and Cervelos having minimalist armrests. Then we get into the interaction effects of arms and bars - which is where the big differences stack up. So this test is by no means conclusive - I saw the DA used in the test at Eurobike and I'm sure I could optimise it to narrow the gap significantly (with only changing minor parts).



Have used the Speedmax CF (the non superbike) as baseline
The very low yaw scenario used here is good for the mavic wheels on the BMC
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Re: New TT bike data from Tour Mag [cyclenutnz] [ In reply to ]
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Where are the error bars? I never trust measurement data that doesn't include error bars. A lot of those measurements could be within the my of error and not statistically different.
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Re: New TT bike data from Tour Mag [Hybridlete] [ In reply to ]
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Hybridlete wrote:
Where are the error bars? I never trust measurement data that doesn't include error bars. A lot of those measurements could be within the my of error and not statistically different.

why not throw in the Gauge R&R too... it would be like my work when I have to show data.
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Re: New TT bike data from Tour Mag [cyclenutnz] [ In reply to ]
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I honestly can't recall the last time I rode my bike without my torso and arms so I'm not sure why this test is relevant? Also, I'm not completely sure on how they set it up, but if they used different tires and wheels on the bikes, again, how is this relevant? The biggest one for me is the testing with legs but nothing else. How do they not see the inadequacies in doing that?
Last edited by: imswimmer328: Sep 9, 17 21:12
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Re: New TT bike data from Tour Mag [imswimmer328] [ In reply to ]
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Pity they have killed the English digital version now, looks like I won't read Tour again.
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Re: New TT bike data from Tour Mag [imswimmer328] [ In reply to ]
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imswimmer328 wrote:
I honestly can't recall the last time I rode my bike without my torso and arms so I'm not sure why this test is relevant? Also, I'm not completely sure on how they set it up, but if they used different tires and wheels on the bikes, again, how is this relevant? The biggest one for me is the testing with legs but nothing else. How do they not see the inadequacies in doing that?

That's why I pointed out some of the issues - Tour data always has foibles. They do have the 808 as the benchmark on each bike at least.
The pedaling legs mean that frame/rear wheel/leg interaction is covered (for a given leg shape) but the absence of arms is a big issue as I mentioned.

The test is relevant because we're unlikely to see data on Canyon or BMC from any other testing. So we look at what their numbers say, evaluate the test inadequacies and add the information to the body of knowledge. In an ideal world we'd have good test data on all bikes, but that simply doesn't happen because it costs so much (not just $) to do and there isn't an RoI for anyone in that. So we take what we can get.
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Re: New TT bike data from Tour Mag [cyclenutnz] [ In reply to ]
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Thanks for the data summary :)
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Re: New TT bike data from Tour Mag [Hybridlete] [ In reply to ]
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Hybridlete wrote:
Where are the error bars? I never trust measurement data that doesn't include error bars. A lot of those measurements could be within the my of error and not statistically different.

Error bars would be nice, but I don't see them as necessary to make some general conclusions. If the measurement error were large, then the curves would cross randomly and the sensitivity of these industrial windtunnel balances is usually pretty good. LSWT is +/- 1gram.

The bigger issue should be reproducibility! How many times do you hear about a study where attempts to replicate then results fail. This study is what,... the 10th time the P5 has tested fastest amongst TT bikes and this is the P5-3?

Did anyone catch why they didn't test the P5-6?
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Re: New TT bike data from Tour Mag [grumpier.mike] [ In reply to ]
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grumpier.mike wrote:

The bigger issue should be reproducibility! How many times do you hear about a study where attempts to replicate then results fail. This study is what,... the 10th time the P5 has tested fastest amongst TT bikes and this is the P5-3?


This just goes to show you that kamm tails are all a bunch of marketing BS when the P5 keeps testing better to all those other kamm tail bikes.

And by error bars, I don't just mean the measurement error from the weight balance. I also mean the spread of the measurements since there is turbulence. You won't get just a single number, it is continually changing. Also, how reproducible is it if you run through all the yaw angles and then take the measurements again?
Last edited by: Hybridlete: Sep 10, 17 7:10
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Re: New TT bike data from Tour Mag [Hybridlete] [ In reply to ]
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The seat tube/gussets on the P5 is a Kahm tail as is the stem. They generally aren't as good as a full airfoil, but they seem to have their place. Most windtunnel tests put Speed Concept is close to the P5 at low yaw and faster at high yaw.

When I tested in the windtunnel you spend quite a bit of time taking measurements at each yaw angle. I don't know what their data reduction techniques are exactly, but it could be 1000s of data points. The spreadsheet I received has results for three separate 20 second samples and the CdA didn't very by more than about 0.001 between the three samples.
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Re: New TT bike data from Tour Mag [Hybridlete] [ In reply to ]
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In addition to what grumpier.mike wrote, the lower part of the P5's downtube is a Kamm profile. Oh yeah, the entirety of the Speed Concept is a Kamm profile and it tests nearly in line with the P5 at zero yaw and it's faster at 15 degrees by a good margin. The Speed Concept is a refutation of your theory of Kamm profiles being inferior for bikes.
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Re: New TT bike data from Tour Mag [cyclenutnz] [ In reply to ]
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Hello cyclenutnz and All,

Nice!

There is not much in this world that is perfect (or perhaps everything is perfect) ..... critics be damned ....

Thanks

Cheers, Neal

+1 mph Faster
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Re: New TT bike data from Tour Mag [cyclenutnz] [ In reply to ]
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I'm happy to see that my SLG's are not much slower than the 808's, at least on a Canyon.
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Re: New TT bike data from Tour Mag [grumpier.mike] [ In reply to ]
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grumpier.mike wrote:
When I tested in the windtunnel you spend quite a bit of time taking measurements at each yaw angle. I don't know what their data reduction techniques are exactly, but it could be 1000s of data points. The spreadsheet I received has results for three separate 20 second samples and the CdA didn't very by more than about 0.001 between the three samples.

If you have legs pedaling, your CdA is going to vary by a lot more than 0.001.
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Re: New TT bike data from Tour Mag [Hybridlete] [ In reply to ]
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Hybridlete wrote:
If you have legs pedaling, your CdA is going to vary by a lot more than 0.001.

No.
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Re: New TT bike data from Tour Mag [cyclenutnz] [ In reply to ]
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Thanks for the link.

1) I actually always thought that the Felt IA would be aerodynamically superior to the Felt DA, even at low yaw
2) As for the BMC, I wonder how much the drag is caused by the rear bento. I recently saw one in a shop. The rear storage is really wide (wider than the seatpost), and might be an aero penalty to use. I love how spacious it is though. The rear storage on my Orbea Ordu is very narrow and has limited capacity.
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Re: New TT bike data from Tour Mag [grumpier.mike] [ In reply to ]
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grumpier.mike wrote:
The bigger issue should be reproducibility! How many times do you hear about a study where attempts to replicate then results fail. This study is what,... the 10th time the P5 has tested fastest amongst TT bikes and this is the P5-3?

Any study that doesn't have the P5 fastest would have some serious questions asked of it...
The results make sense - the Canyon CF SL is ~1min slower than the SLX. So the same kind of differential as P5 to P3 (according to Damons 68g difference) for a similar set of changes (high mount rear brake, no bayonet, standard bars).
Bare P5 faster than P5X

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Did anyone catch why they didn't test the P5-6?
They were doing the best Tri and best TT setups from each brand. It would seem that, if you don't specify that tri means carrying a lot of fuel, the P5X is not the fastest tri option from Cervelo.
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Re: New TT bike data from Tour Mag [bloodyshogun] [ In reply to ]
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bloodyshogun wrote:
1) I actually always thought that the Felt IA would be aerodynamically superior to the Felt DA, even at low yaw

That's what the Felt testing said. But we don't have enough other data points to decide who is correct. The hidden brake on the DA has been an addition since the IA data was released. And the DA in this test had Profile Aeria Ultimate bars, which may have had an impact.
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2) As for the BMC, I wonder how much the drag is caused by the rear bento. I recently saw one in a shop. The rear storage is really wide (wider than the seatpost), and might be an aero penalty to use. I love how spacious it is though. The rear storage on my Orbea Ordu is very narrow and has limited capacity.

Could be that the draftbox interacts poorly with the tour legs (I don't know what effective STA they use), or that the seattube shape works much better when it has the seatpost behind it to form a really long airfoil. I can't see why the V bars would be responsible for such a drop in performance.
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Re: New TT bike data from Tour Mag [cyclenutnz] [ In reply to ]
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Interesting. What tires on the Jet6+ wheels?

Oh yeah...are the Mavic tires still made by Tufo? If so, leaving out Crr effects is key...

http://bikeblather.blogspot.com/
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Re: New TT bike data from Tour Mag [cyclenutnz] [ In reply to ]
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I wonder if there is much difference for the P5 with a UCI legal bottle e.g Elite Crono. I have wondered if this is where bikes like the Giant Trinity catch up as it's down tube bottle is supposedly aero neutral.

I guess at the end of the day these small differences are lots in the far greater noise of rider position.
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Re: New TT bike data from Tour Mag [boing] [ In reply to ]
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boing wrote:
I wonder if there is much difference for the P5 with a UCI legal bottle e.g Elite Crono. I have wondered if this is where bikes like the Giant Trinity catch up as it's down tube bottle is supposedly aero neutral.
Any shape advantage of that bottle would be lost if you tried to drink from it. The removal/engagement not that flash
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I guess at the end of the day these small differences are lots in the far greater noise of rider position.

Rider position, clothes, tyres, hydration placement - all far more significant. Always nice to know where to spend your money for the frame though (Cervelo)
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Re: New TT bike data from Tour Mag [cyclenutnz] [ In reply to ]
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[/quote]Any shape advantage of that bottle would be lost if you tried to drink from it. The removal/engagement not that flash
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Unfortunately Aero UCI legal options are limited. It's such a small market I guess that the Elite/Tacx seem to be the only aftermarket options and I doubt that will change much.
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