BMC TMR01 vs. Giant Propel

Discuss light weight issues concerning road bikes & parts.
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basilic
Posts: 662
Joined: Wed Jan 05, 2011 8:05 am
Location: Geneva, Switzerland

by basilic

Courant, thank you for the very clear explanations.

VNTech, would it be possible for you to run the same 4 tests with and without a mannequin? You'd have 6 pairwise deltas under 2 conditions, enough to at least get an idea about the applicability of the riderless comparisons. If the differences are very close, you can go back to riderless tests with greater confidence. If not, at least you won't be wasting your time from then on. Either way, money well spent.

And btw, why are the bike+mannequin tests much more expensive? is it because the mannequuin position is hard to reproduce and you have to do repeat runs to get reliable data?

VNTech
Posts: 195
Joined: Tue Jan 25, 2011 8:08 pm

by VNTech

If someone wants to send me a check for a few thousand $$, we'll run both tests...

We're well aware of the limitations of various protocols. I'm not an aerodynamicist, I'm a journalist; that means I'm not an expert, but I'm good at finding experts and using their expertise to make sure we do things properly.

Frankly, we didn't go with a mannequin last time because it wasn't ready, and a bad mannequin is far worse than no mannequin. I'm debating going with one for the next test. The positive is that it (probably) provides a better look into what's really happening, the negative is that we can't compare to previous tests (though we were always reticent to do so anyway, as small conditional changes can have an impact).

For what it's worth, our non-mannequin test showed very similar results to both Giant's mannequin testing and Cervelo's mannequin testing — looking at the relative strength/weakness of each model. So I wouldn't call a non-mannequin test useless.

This is also why we don't use the Tour "numbers only" model. Every bike gets ridden, and ridden a lot. In our scoring, quantitative and qualitative are equal. It's not uncommon for the best bike in the lab to lose overall — as the S5 did last year. It won handily in the wind tunnel, but it rides like a block of wood. The Propel lost significant points for its stupid brakes this year. The segment of consumers that cares only about wind tunnel results is a very small one indeed. We try to balance it all, and ask the question "which one would we buy?"
VeloNews Magazine/VeloNews.com tech

Courant
Posts: 106
Joined: Fri Jan 09, 2009 12:36 pm

by Courant

Caley,

That's fair enough, I'm not trying to bash the testing or the attempt at more aerodynamic testing, this is really welcome! For your next test, do go with a decent mannequin and do publish the differences to the without case, this would be a really interesting study, and really educational for all involved.

And, for the record, I bought a Helium because I test-rode a Noah and didn't get on at all with it, so I agree aero isn't everything ;-)

airwise
Posts: 1049
Joined: Tue Jul 27, 2010 8:31 pm

by airwise

IIRC the Tour test with the automated mannequin resulted in the BMC saving just ten watts compared to a bog standard Canyon F8 at 45kph - less when you fitted water bottles.

Now forgive me but buyers need to ask firstly how often they ride on the flat at 45kph. Then ask how many watts they need to be putting out to do so into a slight headwind. Then work out what percentage of that figure about 8 watts is.

Then go and buy an aero helmet, shoe covers, an aero bar and spend the rest on a really good training camp vacation in the mountains.

theloper
Posts: 140
Joined: Mon Sep 03, 2007 10:02 pm
Location: florida

by theloper

VNTech wrote:If someone wants to send me a check for a few thousand $$, we'll run both tests...

We're well aware of the limitations of various protocols. I'm not an aerodynamicist, I'm a journalist; that means I'm not an expert, but I'm good at finding experts and using their expertise to make sure we do things properly.

Frankly, we didn't go with a mannequin last time because it wasn't ready, and a bad mannequin is far worse than no mannequin. I'm debating going with one for the next test. The positive is that it (probably) provides a better look into what's really happening, the negative is that we can't compare to previous tests (though we were always reticent to do so anyway, as small conditional changes can have an impact).

For what it's worth, our non-mannequin test showed very similar results to both Giant's mannequin testing and Cervelo's mannequin testing — looking at the relative strength/weakness of each model. So I wouldn't call a non-mannequin test useless.

This is also why we don't use the Tour "numbers only" model. Every bike gets ridden, and ridden a lot. In our scoring, quantitative and qualitative are equal. It's not uncommon for the best bike in the lab to lose overall — as the S5 did last year. It won handily in the wind tunnel, but it rides like a block of wood. The Propel lost significant points for its stupid brakes this year. The segment of consumers that cares only about wind tunnel results is a very small one indeed. We try to balance it all, and ask the question "which one would we buy?"


Frankly the more "Real World" conditions for the test the better. That means testing with a pedaling mannequin , 2 bottles and cages. Would also be great to see a standard round tubed bike tested in the same conditions to see what the real benefit of an aero frame.

g32ecs
Posts: 143
Joined: Thu Apr 11, 2013 2:50 am

by g32ecs

airwise wrote:Now forgive me but buyers need to ask firstly how often they ride on the flat at 45kph. Then ask how many watts they need to be putting out to do so into a slight headwind. Then work out what percentage of that figure about 8 watts is.

Then go and buy an aero helmet, shoe covers, an aero bar and spend the rest on a really good training camp vacation in the mountains.

People LOVE hearing scientific numbers, etc to justify their purchases.

Just buy what appeals to you.

MarkTwain
Posts: 179
Joined: Sat Feb 23, 2013 10:51 pm

by MarkTwain

airwise wrote:Then go and buy an aero helmet, shoe covers, an aero bar and spend the rest on a really good training camp vacation in the mountains.

But not wheels. Which has better science behind them than any of the above (especially the mountains training camp).

:lol:

airwise
Posts: 1049
Joined: Tue Jul 27, 2010 8:31 pm

by airwise

Bugger science Mark. I am talking about enjoying yourself.

airwise
Posts: 1049
Joined: Tue Jul 27, 2010 8:31 pm

by airwise

In all seriousness I'm assuming people worried about aero already consider deep section rims to be mandatory. Of course if they were living in Provence they might change their mind ;)

As an above poster mentioned, just get whatever makes you happy. My only concern is that of magazines and forums perpetrating myths rather than exposing them.

NGMN
Posts: 1536
Joined: Mon May 30, 2005 7:13 am

by NGMN

Do we need to have the aero denial fest every time its talked about. Aero frames have now been tested on velodromes, through powermeter testing, and in a variety of wind tunnel tests. There is a shit ton of data from a variety of testing methods showing them to be faster. Hell even specialized is doing peloton type testing. Look, if 5-15 watts isn't worth it to you, fine, don't buy the product. But don't bring this asinine denial up every time. Its funny how aero testing evolves, gets more recise, hones in on variables and the deniers spew the same dumb stuff.

xoxo,
guy on a round tubed roadie cause I'm cheap, not because I deny science.

airwise
Posts: 1049
Joined: Tue Jul 27, 2010 8:31 pm

by airwise

NG. There IS no science to show that an aero bike in a mass start event is worth anything at all. That is the message.

My position. If you are racing you will spend a good proportion of any event siting behind other riders where the figures go out of the window. If you aren't racing, what on earth are you worrying about a hyperthetical ten seconds for? And lest we forget, the tests do not show rider fatigue, interruption to pedal stroke, the need to get off the saddle on poor roads or any other numerous potential side affects of using an aero bike for road racing.

ajmit3
Posts: 205
Joined: Sun Mar 27, 2011 7:36 am

by ajmit3

airwise wrote:NG. There IS no science to show that an aero bike in a mass start event is worth anything at all. That is the message.

My position. If you are racing you will spend a good proportion of any event siting behind other riders where the figures go out of the window. If you aren't racing, what on earth are you worrying about a hyperthetical ten seconds for? And lest we forget, the tests do not show rider fatigue, interruption to pedal stroke, the need to get off the saddle on poor roads or any other numerous potential side affects of using an aero bike for road racing.


This. :smartass:

MarkTwain
Posts: 179
Joined: Sat Feb 23, 2013 10:51 pm

by MarkTwain

airwise wrote:NG. There IS no science to show that an aero bike in a mass start event is worth anything at all. That is the message.

For a Sky fan-boy, how you can be so dismissive of aero bike marginal gains is staggering.

airwise
Posts: 1049
Joined: Tue Jul 27, 2010 8:31 pm

by airwise

Ignoring the rather predictable and hopelessly inaccurate snipe, simply put, because there is NO evidence of ANY net marginal gain under normal racing circumstances.

r_mutt
Posts: 331
Joined: Sat Feb 23, 2008 6:33 pm

by r_mutt

airwise wrote:Ignoring the rather predictable and hopelessly inaccurate snipe, simply put, because there is NO evidence of ANY net marginal gain under normal racing circumstances.



Just. Ecause you are sting behind another ride(s), does mean there is no wind resistance. For better or for worse, science doesn't lie- 2 watts or 30 watts.

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