Aero - don't believe the hype?
Comments
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Aero looks cooler. (IMO)0
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I think we can all agree that aero looks amazing but in reality, even when testing aero designs in the wind tunnel you can see a gain (or a loss) then run a totally different test and see the same results.
Just because a result says something is more aero doesn't mean it "travels faster" either. You can also gain in speed but have more drag, likewise you can have a reduction in drag and go slower. Better still, you can reduce drag and see gains on one run and see losses on another without making a single change between the two runs.
In almost all cases you can see a reduction of drag using a wind tunnel and use that in marketing yet in reality it could be a worse design overall. Likewise you can see losses on the wind tunnel yet on the road it performs amazingly.
You have to use the wind tunnel as a guide.Living MY dream.0 -
VTech wrote:I think we can all agree that aero looks amazing but in reality, even when testing aero designs in the wind tunnel you can see a gain (or a loss) then run a totally different test and see the same results.
Just because a result says something is more aero doesn't mean it "travels faster" either. You can also gain in speed but have more drag, likewise you can have a reduction in drag and go slower. Better still, you can reduce drag and see gains on one run and see losses on another without making a single change between the two runs.
In almost all cases you can see a reduction of drag using a wind tunnel and use that in marketing yet in reality it could be a worse design overall. Likewise you can see losses on the wind tunnel yet on the road it performs amazingly.
You have to use the wind tunnel as a guide.
You. What?0 -
I think it was quite self explanatory.
The point is that when using a wind tunnel you can make most changes look good but that doesnt mean it performs where it counts. You can also run totally different tests and get the same results which would suggest that something isnt quite right.
As above, the wind tunnel is a guide, a very good guide but a guide non the less.Living MY dream.0 -
VTech wrote:My wife is away tomorrow for a few days with the girls topping up their tans so I've played the "come on love, it's only fair" card several times already
Odd how they would want to go away on holiday without you.......0 -
ShutUpLegs wrote:VTech wrote:My wife is away tomorrow for a few days with the girls topping up their tans so I've played the "come on love, it's only fair" card several times already
Odd how they would want to go away on holiday without you.......
OK, so what if I bit each time and instead said something like,
I had to get rid of her so I could spend time with your wife/mom/sister/ etc ?
The posts you make lead only one way my friend.Living MY dream.0 -
http://www.cervelo.com/en/engineering/t ... -aero.html
Here you go, according to Cervelo, it's 35 seconds over 195km!
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greasedscotsman wrote:http://www.cervelo.com/en/engineering/thinking-and-processes/weight-vs-aero.html
Here you go, according to Cervelo, it's 35 seconds over 195km!
That doesnt really help (not trying to argue here) as so many factors would be needed to get a true and 100% reliable result which is why most people who test aero products take from the tests the good and forget about the bad.
Now im not saying this is the case with any of the manufacturers mentioned here but it is the general consensus.
It isnt just the weight vs aero factors either as you can make something lighter and more slipstream yet it will be slower in real world. This IS the case in around 97% of aero testing, you often find things that would seem to be of little benefit give great results as well so there is no real science to the findings.
You have to understand that to get the best out of something (or as close to it as possible) costs money and time, man hours, research etc and the pressure on manufacturers to get the product ready will always be a major factor in what items are for sale.Living MY dream.0 -
Simon Masterson wrote:VTech wrote:Maybe in racing its more important to keep weight down that worry how long a frame will last ?
Exactly. Gear for the pro ranks only has to last a few races, if only just a single stage.
As for lightweight carbon frames, they can fail. Steel frames can also fail. I think both are great (though I only own the latter at present), but purely in longevity and durability terms, were I presented with an old steel bike and an old carbon bike, both of which had seen a great deal of active service, I would trust the steel one with my life more, simply because steel frames don't tend to fail suddenly like carbon ones do, and the signs of impending doom tend to be much more apparent. Steel also copes better with non-design loads, and is much more easily repaired (particularly if it's a lugged frame) than carbon fibre.
None of that would deter me from buying a carbon fibre bike, but if I had a choice of a 6.8kg all-carbon world tour level bike and an 8-9kg 953 bike with slightly heavier hubs and metal parts, I would have more long-term confidence in the latter. I'm aware that now I've said that someone will prove me wrong.
OK, I don't get this. We aren't talking about Pro bikes, are we? What manufacturer is going to make a bike to sell to the general public that only lasts 1 ride/race? What sort of time scales are we talking about? I have a Specialized Tarmac SL that I bought in 2007, weighs 6.8, should I be thinking of replacing it? Or what about the Allez Epic I bought in 1991, should I get rid of that as well?0 -
VTech wrote:greasedscotsman wrote:http://www.cervelo.com/en/engineering/thinking-and-processes/weight-vs-aero.html
Here you go, according to Cervelo, it's 35 seconds over 195km!
That doesnt really help (not trying to argue here) as so many factors would be needed to get a true and 100% reliable result which is why most people who test aero products take from the tests the good and forget about the bad.
Now im not saying this is the case with any of the manufacturers mentioned here but it is the general consensus.
It isnt just the weight vs aero factors either as you can make something lighter and more slipstream yet it will be slower in real world. This IS the case in around 97% of aero testing, you often find things that would seem to be of little benefit give great results as well so there is no real science to the findings.
You have to understand that to get the best out of something (or as close to it as possible) costs money and time, man hours, research etc and the pressure on manufacturers to get the product ready will always be a major factor in what items are for sale.
I'm not trying to present Cervelo's data as a final, all encompassing answer, but I do think it's interesting none the less. I am very suprised that according to their figures an aero bike is better for something like the Marmotte than a light bike, I would have thought it the other way round. Sure there are lots of variables this method cannot factor in, but do you not find that interesting?
I'm not to sure how you expect anyone to prove this one way or the other as you have rejected wind tunnels as well, what do you think the solution is? Surely it's a combination of methods, including testing on the road (although I think I would favour a velodrome). OK, maybe not all bike manufacturers do due to the constraints you mention. Interested in where you got 97% from.0 -
Im not rejecting wind tunnels, we use them all the time. my point is that even when we test and prove something in the tunnel, it doesnt always work on the track.
97% is a "rule of thumb" if you make 100 alterations and get 3 positives your doing well.
I would guess that Cervelo are a setup that do a lot of testing and like anyone would grasp the good and dismiss the bad, its just the norm in all developments. I can understand that a heavier setup would work better in some scenarios than a lighter bike and vice-versa.
Likewise, aero modifications could work in one situation but show negative in another.Living MY dream.0 -
So what we're saying is in certain situations an aero road bike can be faster.0
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Sorry, I think ive not made it clear.
What I mean is that just because something is more aero, doesnt make it faster, it doesnt mean that if you test in a tunnel and it has less resistance that it will be faster when used, if only it were that simple
So yes, in certain circumstances just because its aero doesnt make it faster.Living MY dream.0 -
Yeah, I do get what you mean. You could make a bike very aero, but at the cost of rigidity, which means on the road it could be slower. I think the early Felt ARs were a bit like that. But that doesn't mean all aero bikes are like that.0
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greasedscotsman wrote:Yeah, I do get what you mean. You could make a bike very aero, but at the cost of rigidity, which means on the road it could be slower. I think the early Felt ARs were a bit like that. But that doesn't mean all aero bikes are like that.
No, I dont for a minute suggest that, and even further, you could get a very rigid aero that in the tunnel slips like a hot knife through butter but in real terms is slower than a less aero.
In general terms aero should perform well but you get to a point where you can go too far, thinner, wider planes can hit the cross wind and slow you down immensely. There are so many factors.
On an enclosed circuit you could have a super slick aero and it performs very well yet on the road is a total nightmare.
We have tested so many alterations and even if on the computer and in the tunnel they show well, it is more often than not that it doesnt.Living MY dream.0 -
VTech wrote:We have tested so many alterations and even if on the computer and in the tunnel they show well, it is more often than not that it doesnt.
So how are you doing real world testing, to compare to the computer and the wind tunnel?0 -
We typically use weight balances on components and telemetry.Living MY dream.0
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Hmm, not sure I get that, want to explain it a bit more?0
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Its quite high tech and secretive but on the whole we will initially test with a computer, then to the design and testing in the tunnel and once this is passed its tested in "real life"
We use weights to stress test components and aero panels/sections and also telemetry to see if we are actually seeing improvements in time elapsed. We also simulate using this data for various situations and circuits to see if the results pan out.Living MY dream.0 -
OK, fair enough. Interested in this, but I can understand why you don't want to go into more detail. Also doesn't mean that it isn't a perfect testing method as well though.
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So what I really want to know is... Is my spesh roubaix comp going to catastrophically fail when I'm whizzing downhill at 30 mph?0
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Mikey23 wrote:So what I really want to know is... Is my spesh roubaix comp going to catastrophically fail when I'm whizzing downhill at 30 mph?
What about my Cervelo S3, will I be going faster when it fails? 0 -
I think the chances are very slim.Living MY dream.0
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VTech for PM, that's what I say!! B'TWIN Triban 5A
Ridgeback MX60 -
VTech wrote:Its quite high tech and secretive
When you say 'secretive' do you mean you need security clearance to be able to work in this industry?0 -
ShutUpLegs wrote:VTech wrote:Its quite high tech and secretive
When you say 'secretive' do you mean you need security clearance to be able to work in this industry?
As in we don't give our secrets away, it's development.
And yes, you would need clearance to get certain information. Do you have info we could use then ?Living MY dream.0 -
greasedscotsman wrote:Simon Masterson wrote:VTech wrote:Maybe in racing its more important to keep weight down that worry how long a frame will last ?
Exactly. Gear for the pro ranks only has to last a few races, if only just a single stage.
As for lightweight carbon frames, they can fail. Steel frames can also fail. I think both are great (though I only own the latter at present), but purely in longevity and durability terms, were I presented with an old steel bike and an old carbon bike, both of which had seen a great deal of active service, I would trust the steel one with my life more, simply because steel frames don't tend to fail suddenly like carbon ones do, and the signs of impending doom tend to be much more apparent. Steel also copes better with non-design loads, and is much more easily repaired (particularly if it's a lugged frame) than carbon fibre.
None of that would deter me from buying a carbon fibre bike, but if I had a choice of a 6.8kg all-carbon world tour level bike and an 8-9kg 953 bike with slightly heavier hubs and metal parts, I would have more long-term confidence in the latter. I'm aware that now I've said that someone will prove me wrong.
OK, I don't get this. We aren't talking about Pro bikes, are we? What manufacturer is going to make a bike to sell to the general public that only lasts 1 ride/race? What sort of time scales are we talking about? I have a Specialized Tarmac SL that I bought in 2007, weighs 6.8, should I be thinking of replacing it? Or what about the Allez Epic I bought in 1991, should I get rid of that as well?
We may not be talking about grand tour level bikes, I grant you - no prototype parts and not quite as blingy specs (etc) - but fundamentally the same principles apply. I commonly read of extremely light rims (eg. those on extremely light factory wheels) developing cracks within relatively few miles, and for that reason I do think there's a lot to be said for a fair few road cyclists these days deeming very short service lives to be normal and acceptable, but nevertheless I'm not suggesting that every bike that has fairly flimsy hubs in order to allow the wheels to be as light as they are (for example) is going to need new ones within two years; merely that they probably aren't going to withstand decades of hard use, as will something slightly heavier and stouter.0 -
Simon Masterson wrote:We may not be talking about grand tour level bikes, I grant you - no prototype parts and not quite as blingy specs (etc) - but fundamentally the same principles apply. I commonly read of extremely light rims (eg. those on extremely light factory wheels) developing cracks within relatively few miles, and for that reason I do think there's a lot to be said for a fair few road cyclists these days deeming very short service lives to be normal and acceptable, but nevertheless I'm not suggesting that every bike that has fairly flimsy hubs in order to allow the wheels to be as light as they are (for example) is going to need new ones within two years; merely that they probably aren't going to withstand decades of hard use, as will something slightly heavier and stouter.
The UCI weight limits keep things sensible. Pro tour wheels are light but then they are normally tubulars so you save a lot of weight there. But remember, you can get bomb proof alloys from the likes of Campag that weigh little more than 1400 grams. Knocking off another 2 or 300 grams without going tubular is a difficult job but it is debatable whether it is worth it. You could get some Mavics with carbon spokes and, again, they are probably perfectly durable - but a broken spoke will cost a small fortune to fix. But then you might never, ever break a spoke.
Lightness doesn't necessarily always mean flimsiness or short life expectancy and I have no concerns that my carbon bikes are any more or less likely to see me out than a steel framed bike. As for Pro Tour bikes - they have little need to save weight at the expense of durability because they don't need to be that light anyway. But they will tend to have top end parts because the component sponsors will want the bikes to be seen with that kit.Faster than a tent.......0 -
Aero is important. Going as fast as you can, on a flat road, that's where almost all of your power is going. The UCI-mandated diamond-shaped frame limits the improvements that can really be made. And since the chord of an aero feature has been limited in regulations the improvements that can be found are even smaller.- - - - - - - - - -
On Strava.{/url}0 -
Simon Masterson wrote:We may not be talking about grand tour level bikes, I grant you - no prototype parts and not quite as blingy specs (etc) - but fundamentally the same principles apply. I commonly read of extremely light rims (eg. those on extremely light factory wheels) developing cracks within relatively few miles, and for that reason I do think there's a lot to be said for a fair few road cyclists these days deeming very short service lives to be normal and acceptable, but nevertheless I'm not suggesting that every bike that has fairly flimsy hubs in order to allow the wheels to be as light as they are (for example) is going to need new ones within two years; merely that they probably aren't going to withstand decades of hard use, as will something slightly heavier and stouter.
I agree with you, I don't want to buy parts that only last a couple of years, but also I don't think I would be expecting a pair of wheels to last decades. Surely the braking surface isn't going to last that long even if the rest of the wheel does. That might change if disc brakes become more common place, but at the moment, that's not really the case.0
