Why you need aero wheels

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thelawnet
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Joined: 27 Aug 2010, 12:56am

Why you need aero wheels

Postby thelawnet » 11 Dec 2018, 3:28pm

Some usual shilling for shiny stuff here.

https://road.cc/content/feature/213876- ... ind-tunnel

They start off by claiming that it's more important for slow riders to go aero, by using a different and useless measure.

They then move on to saying at a mere average speed of 30kph you'll save some seconds over 120km with 1200m climbing.

And the finally they admit that disc brakes basically waste the aero gains but they don't want to go into that too much because it will disturb the next review where they say you MUST have discs on your next bike.

They do acknowledge, btw, that the aero costs of discs aren't just because of the discs but also the extra spokes for, er, strengthening. Possible weakness of aero wheels as a result of these missing spokes is not discussed.

I'm sure there's an article somewhere about the relative aero gainz/penalty of aero bling vs disc bling, and consequently the actual gainz of aero&discs Vs a standard box.section wheel with rims.

Samuel D
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Re: Why you need aero wheels

Postby Samuel D » 11 Dec 2018, 5:09pm

thelawnet wrote:They start off by claiming that it's more important for slow riders to go aero, by using a different and useless measure.

Not the first time I’ve heard that argument, but it’s playing with statistics at its best, isn’t it! It also assumes slow riders are all earnestly racing. In reality, most slow cyclists aren’t racing, and indeed never have so few cyclists of any sort raced; hence the crisis of membership of racing federations in many European countries and America.

Which isn’t to say slow cyclists don’t want to go as fast as they can, but as usual the article exaggerates the benefit of aerodynamic wheels while downplaying, nay, ignoring, the downsides of wheels that cost ten times more than mine but have half the strength and lifespan.

It will be fascinating to see if this irrational trend of spending a fortune for minuscule and anyway pointless performance gain will continue indefinitely – the new normal of consumerist cycling – or whether there will be a correction and rebellion against all of this, a bit like there has been a rebellion against recreational cycling as road racing (with the gravel trend, etc.).

LittleGreyCat
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Re: Why you need aero wheels

Postby LittleGreyCat » 11 Dec 2018, 5:21pm

Next step up from a MAMIL is a skin suit and an aero helmet with a pointy back.
Oh, and an artificial hunch.

rfryer
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Re: Why you need aero wheels

Postby rfryer » 11 Dec 2018, 5:55pm

There was an interesting GCN video on aero wheels last week. From memory, they showed that in real world conditions, the effort required to maintain 41kph reduced from 379W to 345W when switching from decent quality aluminium box-section rims to top-end deep-section carbon.

This was enough to allow the tester to sustain that speed for over 50 minutes, rather than 20 minutes.

Brucey
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Re: Why you need aero wheels

Postby Brucey » 11 Dec 2018, 6:24pm

rfryer wrote:There was an interesting GCN video on aero wheels last week. From memory, they showed that in real world conditions, the effort required to maintain 41kph reduced from 379W to 345W when switching from decent quality aluminium box-section rims to top-end deep-section carbon.

This was enough to allow the tester to sustain that speed for over 50 minutes, rather than 20 minutes.


well I'd be pleased if I got that result, for about ten seconds.

Ten seconds is about how long it would take to work out that this improvement in speed vs power is obtained only by reducing the whole aero drag (I.e.of the bike plus rider together) to less than 9/10ths of its previous value. You don't need to be a genius to spot that (even if you say halve the drag on the wheels) the wheels alone would have to have been contributing 20% of the entire aero drag. Which is 'obvious nonsense'.

I don't know what is more depressing; that folk watch this guff and believe it or that folk are daft enough to put it out there in the first place.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

peetee
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Re: Why you need aero wheels

Postby peetee » 11 Dec 2018, 7:04pm

And to think, for years now racing cyclist have had to deflect comments about their shaved legs being for aerodynamic reasons. The usual response is that the gain would be so small as to be not worth the effort. Well clearly marginal gains are in so come on, get busy in the wind tunnel. I wanna know what watts? And how many secs will shaving shave?
Winter had arrived in the land of Kernow. Along with it came wet roads and cool winds.
“Oh, my wheels and coupling rods!” Peetee exclaimed.

Des49
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Re: Why you need aero wheels

Postby Des49 » 11 Dec 2018, 7:18pm

peetee wrote:And to think, for years now racing cyclist have had to deflect comments about their shaved legs being for aerodynamic reasons. The usual response is that the gain would be so small as to be not worth the effort. Well clearly marginal gains are in so come on, get busy in the wind tunnel. I wanna know what watts? And how many secs will shaving shave?


One minute over 40km apparently! A pretty significant difference for some. Sure I saw something once on beards too!
Me, never bothered to shave my legs and never will.

https://www.bikeradar.com/road/gear/art ... nds-44601/
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rfryer
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Re: Why you need aero wheels

Postby rfryer » 11 Dec 2018, 7:35pm

Brucey wrote:I don't know what is more depressing; that folk watch this guff and believe it or that folk are daft enough to put it out there in the first place.

Turns out the video is 3 years old, but I watched it last week! Link is here.

Anyway, although the gains seen implausible, I also think it's highly improbable that GCN were deliberately faking the results. So I'm curious about why they saw what they did.

Brucey
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Re: Why you need aero wheels

Postby Brucey » 11 Dec 2018, 8:02pm

real science is 'really difficult'. If you don't have all the conditions absolutely nailed down you could do 'the experiment' ten times and get ten completely different answers.

cheers
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Greystoke
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Re: Why you need aero wheels

Postby Greystoke » 11 Dec 2018, 9:18pm

When I was at school my maths teacher proved that 1+1 was 3.....
You can prove anything with maths & statistics

LittleGreyCat
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Joined: 7 Aug 2013, 8:31pm

Re: Why you need aero wheels

Postby LittleGreyCat » 11 Dec 2018, 9:54pm

Why do cyclists shave their legs, but women wax?
Scientists please explain.

Oh, and do skinny legs reduce drag more than shaving?

peetee
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Re: Why you need aero wheels

Postby peetee » 11 Dec 2018, 10:02pm

Greystoke wrote:When I was at school my maths teacher proved that 1+1 was 3.....
You can prove anything with maths & statistics


Like the fact that learning the alphabet is 2.6 times more difficult than learning numbers. 8)
Winter had arrived in the land of Kernow. Along with it came wet roads and cool winds.
“Oh, my wheels and coupling rods!” Peetee exclaimed.

rfryer
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Joined: 7 Feb 2013, 3:58pm

Re: Why you need aero wheels

Postby rfryer » 12 Dec 2018, 1:29am

Brucey wrote:real science is 'really difficult'. If you don't have all the conditions absolutely nailed down you could do 'the experiment' ten times and get ten completely different answers.

True. But on the other hand, any attempt to do this rigourously would be criticized as not having any real world relevance to most riders. "But you wouldn't maintain that position for an entire ride...", etc.

I think that the set up described for this experiment isn't awful, and the main thing missing is any attempt to reproduce it a few times to establish whether the reported result is representative or an outlier.

Greystoke
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Re: Why you need aero wheels

Postby Greystoke » 12 Dec 2018, 6:21am

The readers will believe it regardless

amediasatex
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Re: Why you need aero wheels

Postby amediasatex » 12 Dec 2018, 9:02am

Brucey wrote:real science is 'really difficult'. If you don't have all the conditions absolutely nailed down you could do 'the experiment' ten times and get ten completely different answers.


Or worse, keep getting the same wrong answer over and over and declaring it correct ;-)