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Aerodynamic drag....let's discuss this!

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Aerodynamic drag....let's discuss this!

Old 11-19-04, 11:06 PM
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53-11 alltheway
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Aerodynamic drag....let's discuss this!

Let's just face it climbing is over rated...the only people who glorify it are people who can't go fast. Wind resistance is a far greater adversary than gravity (ie, only challege to climbing).

Switching to a comfy 46cm bar and dropping to down as much over the front wheel has done wonders.

I'm just wondering how much drag can be eliminated by switching from a 32 spoke wheelset to a aero 24 spoke wheelset. Anybody have any hard numbers on this?
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Old 11-19-04, 11:25 PM
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Ah, the 53-11 of old. Welcome back.

So many things wrong with this post that I don't even know where to start. So I won't.
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Old 11-19-04, 11:38 PM
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Originally Posted by 53-11 alltheway
Let's just face it climbing is over rated...the only people who glorify it are people who can't go fast.
Obviously, 53-11 hasn't climbed anything worth mentioning.
And that Lance dude who climbed Hautacam probably can't go very fast at all either.
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Old 11-19-04, 11:44 PM
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Honestly Climbing is difficult but there are a few tricks I use to make it easier.

First of all I weight 209 lbs.....supposedly heavy by climbing standards. I suspect the reason why heavier riders have a exponentially harder time climbing is because they are riding on the same width tires at the same pressure as lighter riders.

Duh, If you are climbing you will have more than usual weight transfer to the rear tire----------->the contact patch deformns too much with the heavy guy shifting too much weight over the rear and thus exceeding the load carrying specs of the tire resulting in excessive side wall deformation and resulting in high rolling resistance.

All I do is jack the pressure of my Tufo Elites to 180 psi (max psi is 220..so I am still safe) and viola my tire's load carrying capacity isn't overwhelmed like it would be if I was running typical pressures.

Now back to aerodyanics.....I got the climbing thing all figured out....No challenge there.

Last edited by 53-11 alltheway; 11-19-04 at 11:55 PM.
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Old 11-20-04, 12:03 AM
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Actually, weight matters because it takes more work to elevate a heavy mass then a lite one. Climbing is simply elevating a mass (your body and bike). This is the main reason that many heavy riders are slower climbers. I'm not saying you are wrong, but that is not the main reason for heavy climbers having a hard time.
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Old 11-20-04, 12:13 AM
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It cracks me up that during the hammer rides on flats...I end up dropping a lot of them on climbs and have to end up waiting for them as it levels off...

On the real though...both have their advantages and purposes...It's just best to be an all around good rider
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Old 11-20-04, 01:54 AM
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Now don't taller and heavier riders have larger, longer muscles in their larger bodies to allow them to work. Yes the muscle has to do more work but it is also bigger. Now if the large person loses weight (like me wanted to get to 210 from 235, then I would be able to climb better.

As to wind resistance, it is a major factor after a given speed, and it is what holds you back. If there was not air resistance then it would be much easier to average lets say 30 MPH than if there is...
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Old 11-20-04, 02:21 AM
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Larger guys DO have larger muscles, but the strength difference is not proportional to increase in weight. That is why gymnasts, rock climbers, and cycle climbers tend to small while rugby players and power lifters tend to be large. I think I read once, that to increase muscle size sufficient to double your strength, you need to triple the energy to lift the resultant mass. Now, no one rip me a new one if I got the numbers wrong, but the basic concept is right.
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Old 11-20-04, 02:28 AM
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Right. And so a 150 pound guy pumps his Elites to their max of 220psi. Now what do you do?

Cole
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Old 11-20-04, 02:30 AM
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Originally Posted by Mars
Larger guys DO have larger muscles, but the strength difference is not proportional to increase in weight. .
There is a measure of truth to this.....to give an extreme example look at anything that is really small like insects. Ants can lift objects almost as heavy as their bidies and run around with them.

However, In the case of cyclists I think other factors such as equipment (crank length, tire pressure) are more significant.

You could also say that a 120 lb rider is handicapped because he has to ride the same 15 lb bike the 200 lb rider does. The 200lb rider is carrying proportionally less "dead weight (in the form of bike)" than the 120 lb rider does.
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Old 11-20-04, 02:33 AM
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Originally Posted by fujiacerider
Right. And so a 150 pound guy pumps his Elites to their max of 220psi. Now what do you do?

Cole
The extra psi is only helpful up to a point. If the load is not sufficient the extra psi won't improve the contact patch.....but you already knew that.
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Old 11-20-04, 02:34 AM
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Originally Posted by jedi_rider
It cracks me up that during the hammer rides on flats...I end up dropping a lot of them on climbs and have to end up waiting for them as it levels off...
That's because you are racing n00bs who don't know how to set their bike up.
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Old 11-20-04, 02:49 AM
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Originally Posted by 53-11 alltheway
The extra psi is only helpful up to a point. If the load is not sufficient the extra psi won't improve the contact patch.....but you already knew that.
So you're saying that as long as the contact patch is the same, weight doesn't matter, eh? So is THAT why all those little crotchrockets can pass me going up hill when I'm in my 240SX? Damn. And all this time I felt sure it had something to do with power to weight ratio. Foolish me. Well thanks, 53-11, for showing me the light. I'm gonna go take the 960mm of rubber off of my car and stick on some donuts. THAT should show 'em!


Cole
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Old 11-20-04, 02:50 AM
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Originally Posted by 53-11 alltheway
That's because you are racing n00bs who don't know how to set their bike up.
So, uh.... let's see your race results...

Cole
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Old 11-20-04, 03:21 AM
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No hard numbers on what the difference in wheelsets will net you, but wind resistance does increase to the cube of speed. In other words, once you've reached your aerodynamic speed limit, you need to expend a fortune in energy to gain just a small amount of additional speed... Either that or lower your drag.

Just to toss out some easy (and by their nature, inaccuarate, but close enough for easy comparison) numbers, let's say that a given rider on a given bicycle needs to expend 500 watts of energy to reach 50 mph on flat land. That averages (averages being a key word here) out to 10w per mph. For that rider to reach 51 mph, he needs to churn out an additional 6% more power, or 30 more watts. [(51/50 cubed)*500]

To reach 55mph, he needs to pump out 33% more power! (About 665 watts!)

Note that weight doesn't affect top speed; only the time that it takes to get to that speed.

A better bet is to reduce drag... Get aero bars, bike, helmet, amputate your broad shoulders, and do the wild thing to your bike's top tube while you churn out those big watts...

Me? I'll keep wheezing my way up the hills.

-Erik
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Old 11-20-04, 03:27 AM
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jesus christ, my ignore list isnt so effective when you guys keep replying and bringing his threads to the top of the page...

so why dont you just STOP replying to this OBVIOUS moron so the rest of us wont have to see it?
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Old 11-20-04, 03:52 AM
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Originally Posted by fujiacerider
So, uh.... let's see your race results...

Cole
You don't need to enter sanctioned races to know how to set your bike up.
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Old 11-20-04, 03:57 AM
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Originally Posted by 53-11 alltheway
You don't need to enter sanctioned races to know how to set your bike up.
You also don't need to bench 300lbs to know you can, right?

Cole
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Old 11-20-04, 04:49 AM
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Originally Posted by 53-11 alltheway
I'm just wondering how much drag can be eliminated by switching from a 32 spoke wheelset to a aero 24 spoke wheelset. Anybody have any hard numbers on this?
The hard number? Look down at your speedo (not the one those fruity bodybuilders wear when posing, the one that says MPH). It's 55 sustained.

Throw away that silly spoked wheel and buy discs if you want to really move, unless you don't have the upper body stregnth to hold the bike still in a crosswind. If you keep training and have decent genetics, you'll find you'll be ripping and snapping spokes, even with 40 like some of those old guys run. A disc is really the only way to go.

If you ride a REAL bike (it's called a FIXED GEAR) you can get rid of a lot of drag; shifters, deralliuers, all that junk and the cables can come off.

As for drag I find that wind resistance and thermal build up are my main two problems. At speed the friction causes my skin to heat up and I end up on the verged of heat stroke on most hard rides. Laugh all you want, wind burn is a serious problem so I'm constantly fighting between wearing clothes to protect my arms and legs (full skin suit) and overheating in a full skin suit.

I agree with the little gear man that climbing is overrated. Most climbs have many corners and I keep having to slow down. I find the glue on my tubulars starts melting from the braking heat (there it is, my old nemesis again), too often I rip out valve stems accellerating up out of the corner because of this.

Would clinchers help this? I just fear blow outs at my usual high speeds with a tube...and there aren't any full disc wheels on the market right now that use clinchers.

Last edited by 56-11 Fixed!; 11-20-04 at 05:08 AM.
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Old 11-20-04, 05:03 AM
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*yawn*
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Old 11-20-04, 05:17 AM
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Originally Posted by 56-11 Fixed!
The hard number? Look down at your speedo (not the one those fruity bodybuilders wear when posing, the one that says MPH). It's 55 sustained.

Throw away that silly spoked wheel and buy discs if you want to really move, unless you don't have the upper body stregnth to hold the bike still in a crosswind. If you keep training and have decent genetics, you'll find you'll be ripping and snapping spokes, even with 40 like some of those old guys run. A disc is really the only way to go.

If you ride a REAL bike (it's called a FIXED GEAR) you can get rid of a lot of drag; shifters, deralliuers, all that junk and the cables can come off.

As for drag I find that wind resistance and thermal build up are my main two problems. At speed the friction causes my skin to heat up and I end up on the verged of heat stroke on most hard rides. Laugh all you want, wind burn is a serious problem so I'm constantly fighting between wearing clothes to protect my arms and legs (full skin suit) and overheating in a full skin suit.

I agree with the little gear man that climbing is overrated. Most climbs have many corners and I keep having to slow down. I find the glue on my tubulars starts melting from the braking heat (there it is, my old nemesis again), too often I rip out valve stems accellerating up out of the corner because of this.

Would clinchers help this? I just fear blow outs at my usual high speeds with a tube...and there aren't any full disc wheels on the market right now that use clinchers.
LOL........
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Old 11-20-04, 05:39 AM
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Originally Posted by 56-11 Fixed!
there aren't any full disc wheels on the market right now that use clinchers.
I wonder how much a set of discs would cost me? I bet they are heavy......although aerodynamic.
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Old 11-20-04, 06:10 AM
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Originally Posted by 53-11 alltheway
I wonder how much a set of discs would cost me? I bet they are heavy......although aerodynamic.
You guys kill me. I'm waiting for 60-10 to make an appearance soon.

Discs are heavy...most are around 1000 grams, about the weight of an old school spoke wheel. But the weight is pretty uniform across the whole wheel, so they actually spin up pretty fast. They are VERY fast...

You can find them regularly on Ebay for fairly cheap. I'd steer away from a front disc unless you are riding an indoor track.
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Old 11-20-04, 10:57 AM
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Originally Posted by 53-11 alltheway
Let's just face it climbing is over rated...the only people who glorify it are people who can't go fast. Wind resistance is a far greater adversary than gravity (ie, only challege to climbing).

Switching to a comfy 46cm bar and dropping to down as much over the front wheel has done wonders.

I'm just wondering how much drag can be eliminated by switching from a 32 spoke wheelset to a aero 24 spoke wheelset. Anybody have any hard numbers on this?
From a pure physics perspective your first comment holds some water. As pointed out by a previous poster the power needed to incremental increase speed on the flat is velocity cubed. Whereas, increasing speed on a steep climb is roughly linear with increased power. As also pointed out climbing is pretty much a power to weight ratio with an efficiency factor thrown in. Little people tend to win the power to weight game. Flat cruising is correspondingly a power to aero drag ratio with a little rolling resistance thrown in. Larger people tend to win this game. I for one have always been a better climber than cruiser relative to my racing peers.

Now to your question. Wheel drag is a complex issue. But here's some rough rules of thumb. For spoked wheels with similar rims and lacing patterns the wheel drag can be approximately scaled by the spoke count. So a 24 spoker will have 25% less wheel drag than a 32. The same holds for spoke diameter. Go from 14's to 16's and you pick up 13% more. Go to bladed spokes and the drag decreases significantly with the caveat that they are perfectly lined up in the wheel plane otherwise the drag can increase. Go to a deep dish and things get interesting. One gets two bennies: 1) the wider dish decreases rim drag (I personally believe rim drag is a minor effect - just my gut with no scientific data) and 2) shorter and fewer spokes can be used. Shorter is important because the incremental drag force increases by the square of the spoke length. As pointed out disk wheels will have the lowest drag but anything other than a head wind can be problematic.

If purism is a non-issue I believe the best bang for the aero $ is a frontal faring
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Old 11-20-04, 11:21 AM
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Originally Posted by boyze
As pointed out by a previous poster the power needed to incremental increase speed on the flat is velocity cubed. Whereas, increasing speed on a steep climb is roughly linear with increased power.
Yeah.....that's why I think wind resistance is the greater enemy. Climbing ain't nothing.....I've got power to weight ratio in spades!!

Boyze.....nice info about spoke count and diameter vs. drag.

Last edited by 53-11 alltheway; 11-20-04 at 11:27 AM.
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