Aero vs light wheels

Everything about building wheels, glueing tubs, etc.
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Zen Cyclery
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by Zen Cyclery

cliplessnyc wrote:hmm ok, thanks!
so what about:
ZTR 340 20mm depth vs XR380 38mm depth?

The weight difference is now 400 gr per wheelset (XR380s are obviously heavier).

(Spokes Sapim CX-Ray, 24/24 & 20/24)

???


Well, first off you are definitely talking about two completely different beasts. With the Alpha 340, you could expect much quicker more lively accelerations. They will get up to speed much more quickly than the latter. The 380 on the other hand would be much better for long flat windy rides. Now, even though they will not wind up as quickly, they will be able to maintain average speed with much more ease.

mrfish
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by mrfish

Aren't we doing the same as all the German magazines and measuring the things that can be measured rather than what really counts.

Firstly getting a low position on a bike that fits is a good start. Then if you're riding for more than an hour get a bike that's comfortable. That's probably why all those Cervelo guys were riding their R-series bikes in the tour. The rest makes very little difference.

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djconnel
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by djconnel

Virtually every rider in the Tour uses deep carbon rims instead of alloy box rims which would be more comfortable and have better braking. Don't dismiss aerodynamics. However, it's clear with the frames there's a tradeoff which isn't considered worthwhile.

airwise
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by airwise

And to be fair virtually every rider in Le Tour travels at a much higher velocity than 99.999% of wheel buyers (and weight weenies) - at speeds where aerodynamics actually might make a minor difference. Most of them train on non aero aluminium clinchers.

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kgt
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by kgt

djconnel wrote:Virtually every rider in the Tour uses deep carbon rims instead of alloy box rims which would be more comfortable and have better braking. Don't dismiss aerodynamics. However, it's clear with the frames there's a tradeoff which isn't considered worthwhile.


That's not exactly true. Actually most used low to medium profile wheels. Almost none used really aero wheels like over 50mm.

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DMF
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by DMF

For those of you talking about average speed, excuse my language - but what the h*ll has ´average´ speed got to do with the benefits of aerodynamic frames/wheels/etc?

NO, aero doesn't count ALL the time, EVERYWHERE you ride. Don't expect it to do so either... but on a long flat or in windy conditions something like a deep wheel, and it doesn't even have to be very deep, for sure as hell makes a HUGE, and very, very, very noticeable difference when you're trying to hold on to your speed... and I think about 99% of the members on this forum easily travels at speeds closer to 45-50 km/h+ on the long flats...

So it's really not a question about what aero does at 30 km/h for non of us... you get aero to get fast on the long flats, if you're looking to get fast on the climbs - go lighter weight - if you're looking to go faster downhill - get better brakes and grippier tires. If you're looking to go faster on average - get all of the above...

But talking about aero in the same sentence as average speed, that's just simply beside the point.

And also, the "your sitting position means more than your wheels" is just as ignorant as the good old "take a dumb before you go riding instead of buying lighter parts".

airwise
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by airwise

DMF wrote:
But talking about aero in the same sentence as average speed, that's just simply beside the point.

And also, the "your sitting position means more than your wheels" is just as ignorant as the good old "take a dumb before you go riding instead of buying lighter parts".


Two points to begin with.

Firstly manufacturers and magazines typically test their aero devices in a windtunnel at 40kph and add up the benefit over an hour. That means covering 40km at an AVERAGE of 40kph to get the time benefits hinted at. I don't ride long flats much I'm afraid - can't think of many in most of Europe that real cyclists would head to for competing on.

Secondly, your sitting position IS more important than your wheels. Miles more important. Just go to a wind tunnel - Top Velo did recently. Hell a water bottle is more important than a pair of Zipps.

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DMF
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by DMF

You really, REALLY, missed the point completely on both the points there...

First of all, you may not ride flats, you may not even ever ride solo... But many of us don't actually live in the mountains and many of us do the main part of our riding as solo training rides. In those cases, aero rules! And don't give me that crap about speed doesn't matter if you're not racing - I, as many with me, ride with passion as the main reason for riding at all, and more speed is more fun.

Second of all, the point you really missed - ofcourse sitting position (and waterbottles) make more difference than wheels. But you kind of seem to argue that one can't have both - or that one improvement is obsolete because another improvement is bigger?

It all adds up, and no matter what perspective you put it in, wheels make a huge actual difference when riding solo on the flats!

airwise
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by airwise

No I'm not missing anything here I'm afraid.

You don't seem to understand that your fancy aero setup might be worth 30 seconds over an hour of riding your flats at 40kph (in optimal conditions etc.) How much more fun do you really think going an extra fraction of a kilometer and hour really is?

I'll give you some objective figures taken from wind tunnel testing.

Cervelo R5 40kph
Cervelo S2 40.2kph
Cervelo R5 with Zipp 808/404 40.3kph
Cervelo S2 with Zipp 808/404 40.5kph.

So all that effort and you will be half a kilometer an hour quicker for the same physical output. Now come on! "Huge difference"? 0.5%? Huge? You honestly think going that much quicker is "more fun"? Maybe it is in your head. I'd prefer to just work a little harder and ride with real passion :wink:

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DMF
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by DMF

I said it's easier to hold on to speed when going fast, it's that sensation of effortlessness at high speed. The difference is easily comparable to that of training tires vs racing tires... Now don't get me wrong (again), I'm not saying it's the same only that the size of the difference is just as noticable. If you'd actually bother to try for yourself, I'm certain you'd agree.

Don't say it doesn't work because you fail to put the numbers on it when hundreds and hundreds of people claim the same experience of effortless speed after changing from low-profile wheels, both online, IRL and in magazines.

I mean try it for yourself in real life, it's bloody night and day!

airwise
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by airwise

Well lets see.

I have a Neil Pryde Alize at work.

I have Cosmic Carbone SR's at work.

I have ridden them on numerous occasions. Do they count?

Placebo is a remarkably powerful effect. Objective findings are the only way of bypassing it's influence I'm afraid.

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kgt
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by kgt

DMF wrote:I mean try it for yourself in real life, it's bloody night and day!


Night and day :?:
You may want it to be so but I 'm afraid its not.

See above how many pros ride low profile wheels.
They wouldn 't if facts were as you think they are.

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DMF
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by DMF

So you're saying the only reason anyone gets deep wheels is either for the looks or the placebo, for all other purposes they're completely useless?

Then again, some people can't tell the difference of adding 2 or even 3 kg to the bike and then find som scientific survey showing that the mathematic difference is only 0,xx seconds over x km of distance, supporting their theory that everything is placebo if they can't feel it themselves - while others claim that 3 kg extra on a bike, which on this forum is like 40-50% extra in some cases is night and day.

It's sort of not the first time 'everybody else' seems to suffer from a hard case of the placebos'...

As for what the pros ride, how often do they race solo on a flat course? The advantage of deep wheels goes straight out the window when riding in a group, and as for training solo as a pro they ride to get better - not to have fun, low-profile wheels have better comfort and I bet most pros actually do a fair amount of their training in very hilly areas.

So just because something suits the riding conditions of a pro better, doesn't mean it's the ultimate solution for everyday Joe. But if you are fortunate enough to do your training rides in france, gran canaria, northern italy or likewise - for the love of God don't use deep wheels! ;-)

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DMF
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by DMF

I feel I have to quote this... "Change the wheels, and the bike won't go anywhere near as fast...", from a recent issue of Cycling Plus magazine testing 6 titanium race bikes, where only one has deep section wheels (50mm), and they also reference to having tested the same model earlier with lower profile wheels...

Damn these experienced bike journalists at one of the biggest bike magazines in the world, having tested thousands of bikes and still fall victim to simple placebo. For what it's worth I forgive them though, as it seems to be the case of all journalists testing all bikes with deep section wheels constantly praising their ease of speed.

Mind you, journalists actually riding the bikes, not journalists reading figures from wind tunnel tests and then draw conclusions from that about how it rides.

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djconnel
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by djconnel

airwise wrote:And to be fair virtually every rider in Le Tour travels at a much higher velocity than 99.999% of wheel buyers (and weight weenies) - at speeds where aerodynamics actually might make a minor difference. Most of them train on non aero aluminium clinchers.


We're also putting out less power. Aero is still the main contributor to power as a fraction of the total. The threshold for aero being dominant is closer to 10 mph than 25 mph.

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