Extra speed from deep section wheels...really?
Comments
-
Imposter visit cycling powerlabs website and run the model for a TT with aero wheels and with mavic open pro wheels and see for your self it is the only way you will see.
Actually my post agrees with the "study" you are trying to reference it is just that you picked up the wrong conclusion. The conclusion has a bit more to it.
If I have time tonight I will post a mathatmatical model and run the numbers for you all.
It will be math heavy and I will not do it again so if any one can pin the post that would be good as it comes up again and again.
the formula is
Power = 0.5*Cd*A*rho*V^3 + Crr*mg*v*(cos(theta))+mg*v*sin(theta) Therefore the equation can be solved for v if power is know but it isn't a pretty equation its pretty cumbersome.
The second term is power consumed by rolling resistance which is dependent on the normal reaction force which changes with road gradient (theta is angle not the gradient). I theta is zero (flat road) cos(theta) =1 and therefore the term is irrelevant and the second terms Crr*mg*v. The last term is the power to overcome gravity and will be zero if theta is set at zero.
I have however used this calculator to get some numbers for you I hope this will put it to bed (as I cant be bothered setting up a spreadsheet again). The model used in the aeroweenies website is the same but I think it includes a term for rotational interia of wheels which I am ignoring as it is insignificant in the grand scheme of things.
http://www.aeroweenie.com/calc.html
Rider weight 92kg CdA 0.28 (drops) distance 40km power 200W time taken 1hr08mins08secs or 4088secs
The same rider now with a Cda of 0.27 (saving provided by typical aero wheels vs mavic krysriums) 1hr07mins22secs or 4042 secs
Thats 45 secs or 1.100% time saving
Now for the same rider pushing out 300W
Cda 0.28 time 58mins35secs or 3515 secs
Cda 0.27 time 57mins54secs or 3474secs
time saved 40 secs or 1.138% time saving
So on the face of it time saved for the slower rider is bigger BUT for the faster rider time saved is a bigger % which is what I said what the study/blog by Alex simmonds says we all agree except you imposter who took a headline but missed the underlying point.
If there is something someone does not understand please explain what you dont get and maybe I can iron that one out. but there is no substitute for running the numbers your self to see how the relationships work.
I hope this clears it up once and for all.http://www.thecycleclinic.co.uk -wheel building and other stuff.0 -
So on the face of it time saved for the slower rider is bigger BUT for the faster rider time saved is a bigger % which is what I said what the study/blog by Alex simmonds says we all agree except you imposter who took a headline but missed the underlying point.
This is becoming a comedy classic. I think there must be something wrong with you mate. Stop saying I disagree with it. I haven't disagreed with anything here. I've simply said that there is a study out there which disputes some of what is being said in this thread. I have made no comment on whether I agree with it or not, or whether I believe the findings are correct or not. I actually couldn't give a fck either way. The only point I ever made was that there was a study out there somewhere which contradicted some of what was being said.
I'm beginning to fear for the future of the human race here, what with you bein' a physics teacher n' all...0 -
I really give up sometimes. I have not been rude at any point here but imposter you have been very rude on more than on occasion.
If you are going to post something about a study find it reference it and then we can discuss otherwise your post add little it is a bit like me posting results of the model I have used without stating how I got to them.
The physics here is not in question you will find it in this article are you going to read?
http://www.aeroweenie.com/assets/backup/cervelo_frames/cervelo_position.html
please have a good read before slating me some more.http://www.thecycleclinic.co.uk -wheel building and other stuff.0 -
I really give up sometimes.
I know the feeling.
I'm not interested in proving or disproving anything here. I just said there was a study out there. I also said I couldn't find it - and I have tried several different search terms. We also both know the study being referred to, and the fact that it has been discussed on this forum before. Anyway, I'm out - you can carry on being indignant. I'm off to do something more productive, like sorting out my sock drawer..
0 -
but that's what we're saying - it doesn't contradict it ...So on the face of it time saved for the slower rider is bigger BUT for the faster rider time saved is a bigger % which is what I said what the study/blog by Alex simmonds says we all agree except you imposter who took a headline but missed the underlying point.
This is becoming a comedy classic. I think there must be something wrong with you mate. Stop saying I disagree with it. I haven't disagreed with anything here. I've simply said that there is a study out there which disputes some of what is being said in this thread. I have made no comment on whether I agree with it or not, or whether I believe the findings are correct or not. I actually couldn't give a fck either way. The only point I ever made was that there was a study out there somewhere which contradicted some of what was being said.
I'm beginning to fear for the future of the human race here, what with you bein' a physics teacher n' all...0 -
Yes, but drag increases to the square of velocity.
I thought the relationship was cubic
I'm afraid you thought wrong.
https://www.grc.nasa.gov/www/k-12/airplane/termv.html0 -
What I thought was that trafitional aero wheels (old skool) like hed3 or the narrower V wheels benefit faster riders over slower as they rarely see a yaw angle over 5 degrees. The more recent, fatter U profile aero wheels that are better at higher yaw angles are designed for slower riders. This is because side winds have more of an effect at slower speeds. I feel they are aimed really at age group triathlete sort of speeds. They are actually slower than the narrow deep low yaw wheels at high, say 27mph+ TT speeds.
Therefore the fat, high yaw immune, U shaped rims benefit slower riders more than fast riders. Thankfully, following aero testing last week, I'm getting toward the latter camp and will keep using my Hed trispoke
Insta: ATEnduranceCoaching
ABCC Cycling Coach0 -
Just to back up Imposter I've seen the same study and it does indeed conclude exactly what he says - from memory the reasons were as stevie63 says.
Now whether the study was a load of cobblers or not is another thing but Imposter isn't misrepresenting it.
edit - actually having read the first page maybe he is misrepresenting it when he says the slower rider will get a proportionally bigger benefit ! It is as I think everyone agrees a bigger benefit in total time saved.[Castle Donington Ladies FC - going up in '22]0 -
There is also another point in this argument that need mentioning. That is the affect of wind on your deep wheels.
This is my understanding: what is important is that you are riding a quality set of DEEP (i.e. 58mm+) wheels. Most of the time when you are riding it will be windy. When it's windy and you're riding slower you will be exposed to yaw angles that are (on average) higher than someone who is riding quicker. If you take a look at any graph of drag vs yaw for some deep section wheels you will see that at higher yaw number the drag produced by the wheel is much lower than at low yaw numbers. What's really interesting is that some disc wheels/very deep wheels actually produce negative drag (i.e. they propel you forwards like a sail) but this typically only happens when yaw angles get to double figures (e.g. 12+). A fast rider will rarely experience 10+ but a slower one is much more likely too, particularly when it's windy and you're not just riding straight into the wind. This is why pros usually have a relatively shallow wheel on the front of their TT bikes - at 30mph yaw angles encountered will be very low because they are moving so quickly, therefore there's no point running a deeper wheel.
So, there is a strong case for slower riders using reasonably/very deep wheels in windy conditions. The downside is that you have to be able to keep control of the bike and avoid getting blown into a ditch!0 -
The effect of the best aerodynamic wheels over reasonable ones ist not noticable for normal human beings.
People who tell stories tell de fracto stories about:
Wind conditions
Lots of money spent
Fast "looks"
Fast names on the rims
But really nothing about the real aero benefits, which is at most a couple of seconds in long time trials.
Very over-estimated in general.0 -
The simple truth is that you really need to be able to pedal fast to get the benefits - get an aero wheel above 50kph and really feel the difference, the problem is that many people are simply trundling around at 30kph thinking they are getting some sort of benefit.Make mine an Italian, with Campagnolo on the side..0
-
You may not be able to feel the difference at 30 kph but the maths says otherwise there is a difference.
I can't feel the difference at 30 mph between aero and non aero wheels at that pace pedaling always feels hard.
There have been various tests to show this but as most quote power saved or time saved at 30 mph most folk think that time saved goes down as speed drops. As a raw number of of time saved goes up. To say though aero wheels benefit a slower rider more because as a percentage of time saved it is lower. This is what I am arguing and has been totally missed by those like imposter (I am not having a go now either). He is right and so am I and eveyone else that total time saved is higher for the slower rider but the second conclusion drawn is wrong that aero kit benefits slower riders more. It benefits all riders and faster one by a higher %. The conclusion therefore depends on how the result is expressed and that what folks need to see.
This is the problem with articles the headline is what readers remember not the underlying principle. Often articles like this end up confusing rather than informing which was not the authors intention.
See this on a test between two different bikes. The effect is seen with frames the same applies to wheels.
http://www.cyclingweekly.co.uk/news/latest-news/how-much-faster-is-an-aero-bike-video-176312http://www.thecycleclinic.co.uk -wheel building and other stuff.0 -
[url=http://www.bikeradar.com/forums/viewtopic.php?p=19713712#p19713712]AllezAllezAllez[/url] wrote:Is the correct?
The following was taken from a wheel builder:
"50mm is going to be a bit faster for a novice rider, wanting to get up a group in chaingangs etc. Average speeds can increase 2-3mph over box-section wheels".
Sounds a lot. But does it happen?
Complete rubbish. If that was the case every race would be won by a bloke with deep rims and that's not the case.
2 mph would be a huge difference. I had 50mm on this year and I swapped to normal when the deep rims broke.
I had my best ride of the year the next week when by this theory I'd be 2mph slower ?0 -
...
I would think most people would think % improvements is most relevant.
TT 'handicap' (type) prizes are normally distributed on the best time improvement so slower rider with 70 sec (1.5%) improvement gets the prize & not the faster rider with 60 sec (1.7%) improvementThere is no secret ingredient...0 -
Still waiting to hear which wheel builder made the original bold claim...
No need to wait?
It is straight forward enough to copy the quote into a search engine. Try it yourself. Google comes up with two results and one of those is this thread. "You really think you can burn off sugar with exercise?" downhill paul0 -
In fairness the quote said that average speeds CAN increase by 2-3mph....
Although I don't know of any circumstances in the real world where that will happen and it all sounds very theoretical to me. 50mm alloy clinchers are heavy so impact climbing, 50mm carbon clinchers are expensive and impact descending.0 -
But you have to be going 18mph+ ok.0
-
No that's not true, aerodynamics apply at all speeds - so an aero benefit will apply from 1mph up.
What is true is that although it that at lowers speeds drag is a lower component of the forces you are working against and as speed increases so drag becomes an increasingly higher component since other forces are largely static and drag increases by the square of speed.0 -
[url=http://www.bikeradar.com/forums/viewtopic.php?p=19717573#p19717573]Charlie Potatoes[/url] wrote:Still waiting to hear which wheel builder made the original bold claim...
No need to wait?
It is straight forward enough to copy the quote into a search engine. Try it yourself. Google comes up with two results and one of those is this thread.
Oh dear. Their wheels have a good reputation too.0 -
No that's not true, aerodynamics apply at all speeds - so an aero benefit will apply from 1mph up.
That's not strictly true either - Bernoulli had something to say about that.
It depends, for example, whether the flow over the surface is laminar or turbulent. That, in turn, is impacted by the surface finish, the Reynolds number of the fluid, the angle of attack etc etc these are things swing bowlers and pilots know about...
Suffice it to say that the answer to the OP's title is "It depends" ROAD < Scott Foil HMX Di2, Volagi Liscio Di2, Jamis Renegade Elite Di2, Cube Reaction Race > ROUGH0 -
[url=http://www.bikeradar.com/forums/viewtopic.php?p=19717573#p19717573]Charlie Potatoes[/url] wrote:Still waiting to hear which wheel builder made the original bold claim...
No need to wait?
It is straight forward enough to copy the quote into a search engine. Try it yourself. Google comes up with two results and one of those is this thread.
Oh dear. Their wheels have a good reputation too.
I have a pair. Very happy with them."You really think you can burn off sugar with exercise?" downhill paul0 -
That's not strictly true either - Bernoulli had something to say about that.
.....
Suffice it to say that the answer to the OP's title is "It depends"
Yes, you are correct, I was trying to correct the statement that there is negligable benefit until you get to 18mph.0 -
So if there was a 2-3 mph benefit to deep section wheels, and they weren't effective until 18mph would that mean it was impossible to ride with deep wheels at 19 mph?
I'm joking of course, but let's not mistake a bit of hyperbole for anything which denigrates the guy's wheels.0 -
[url=http://www.bikeradar.com/forums/viewtopic.php?p=19717573#p19717573]Charlie Potatoes[/url] wrote:Still waiting to hear which wheel builder made the original bold claim...
No need to wait?
It is straight forward enough to copy the quote into a search engine. Try it yourself. Google comes up with two results and one of those is this thread.
Just post the result, it's Wheelsmith http://www.wheelsmith.co.uk/aero-beginners-guide0 -
Oh man, I just realised that I average 17.94 mph so if I use them I won't go any faster. If only I was 0.06 mph faster then I would get an extra 2mph turbo boost.0
-
No that's not true, aerodynamics apply at all speeds - so an aero benefit will apply from 1mph up.
What is true is that although it that at lowers speeds drag is a lower component of the forces you are working against and as speed increases so drag becomes an increasingly higher component since other forces are largely static and drag increases by the square of speed.
I was taking the p!ss out of wheelsmiths broscience website, I want serious.0
