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Taking on extra weight to descend faster

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Taking on extra weight to descend faster

Old 07-24-11, 02:57 PM
  #26  
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Originally Posted by Kind of Blued View Post
Good Lord...
My point is that you are oversimplifying it. Different scientific laws are going to contradict each other in this.
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Old 07-24-11, 03:10 PM
  #27  
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Originally Posted by TommyL View Post
My point is that you are oversimplifying it. Different scientific laws are going to contradict each other in this.
No, they're not. If they contradicted each other, they wouldn't be scientific laws.
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Old 07-24-11, 05:55 PM
  #28  
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Originally Posted by Kind of Blued View Post
No, they're not. If they contradicted each other, they wouldn't be scientific laws.
+ Infinity (+/- a few eternities)



Pfffft! So now Newton's Laws of Motion have become subjective? How post-modern...
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Old 07-24-11, 06:32 PM
  #29  
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Originally Posted by Kind of Blued View Post
No, they're not. If they contradicted each other, they wouldn't be scientific laws.
You're being (probably intentionally) pedantic. What he is saying, is that there can be multiple forces at work, each governed by their respective 'scientific laws', with some of them working opposite to each other with respect to their affect on a rider's descent speed. This is certainly true. One example would be the greater deflection of the tire sidewalls, resulting from the addition of weight, which increases drag.

None of this refutes the fact that bigger riders, of equal skill, descend faster. Of course skill is rarely equal, which is why, at 195#, I'm passed by petite women on winding descents!
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Old 07-24-11, 09:01 PM
  #30  
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Originally Posted by AzTallRider View Post
You're being (probably intentionally) pedantic. What he is saying, is that there can be multiple forces at work, each governed by their respective 'scientific laws', with some of them working opposite to each other with respect to their affect on a rider's descent speed. This is certainly true. One example would be the greater deflection of the tire sidewalls, resulting from the addition of weight, which increases drag.

None of this refutes the fact that bigger riders, of equal skill, descend faster. Of course skill is rarely equal, which is why, at 195#, I'm passed by petite women on winding descents!
Thanks AzTallRider, I couldn't have said it better myself. Looking back at my posts, I wasn't getting my point across very clearly.
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Old 07-25-11, 05:07 AM
  #31  
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Originally Posted by Kind of Blued View Post
No, they're not. If they contradicted each other, they wouldn't be scientific laws.
I think influence the result is better for the pedants
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Old 07-25-11, 05:58 AM
  #32  
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I don't care about no stinking physics laws - fat is fast.

I'm 90kg - I do go downhill faster than the 60-70kg guys. Just set us rolling and very soon I'm feathering the brakes to hold my spot in the line while the little guys are pedaling!

No, I don't think it is the quality of my tyres or wheel bearings. I'm certainly not any more aero.
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Old 07-25-11, 08:07 AM
  #33  
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At 260 lbs, the only good reason for hauling my bulk up a hill is to enjoy the speed in going back down the hill. It's about the only time i ever pass anyone.
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Old 07-25-11, 09:29 AM
  #34  
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Originally Posted by DiabloScott View Post
Maybe you just need to ride with some fat guys to observe this phenomenon in person.
My local club used to have pretty much the same ride every Tuesday. I'm fairly large, huge by TDF standards. (About 230). That ride regroups at the High point on Mullholland Drive leaving the San Fernendo Valley. I did it pretty often, so did one of the women who was a top racer in the U.S.

On the decent I would pull away even though she was in an extreme aero position. Of course without the regroup that was no way I would have even seen her on the decent.

On one of the easy weekend rides I had a truely huge rider, about 300 lbs, pass me easily on a short decent. He was just flying downhill.
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Old 07-25-11, 09:35 AM
  #35  
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Originally Posted by prathmann View Post
Jean Robic was supposedly handed lead-filled 'water' bottles at the summits of some climbs to be able to descend faster.
I don't remember who did this, but at one time it was legal to change bikes only if you had a mechanical problem. Some would start with a light bike and a pair of wire cutters. Snip a cable and replace with a heavire bike for the downhill. In this case it was not for weight per se that he change was made, it was that the light bike was pushing the limits of the time and was a bit unstable. Good enough for flat or esp. for going up. Not for high speed decents.
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Old 07-25-11, 10:24 AM
  #36  
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Originally Posted by JonnyHK View Post
I'm 90kg - I do go downhill faster than the 60-70kg guys....
That's nice... and not terribly relevant.

I agree that if when you're on a straight descent, the 90kg rider will descend faster than the 60kg rider with less power required.

However, these are not straight. They're highly demanding technical descents around hairpin turns. Take a corner too fast and you end up in the car park... or worse.

As a result, in the pro races at least, it's not about weight or watts; it's all about road conditions, handling and confidence.
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Old 07-25-11, 10:48 AM
  #37  
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Originally Posted by JonnyHK View Post
I don't care about no stinking physics laws - fat is fast.

I'm 90kg - I do go downhill faster than the 60-70kg guys. Just set us rolling and very soon I'm feathering the brakes to hold my spot in the line while the little guys are pedaling!
Back in the days of itinerant baseball teams, the promotors would get the local high school physics teacher to come out and discuss how throwing a curve ball was impossible because there would be no force vector on the ball after it left the pitchers hand - it could only be an optical illusion. Then they'd set up a couple tall poles and the pitcher would pitch around them in a way that proved the ball was curving. The problem wasn't that the physics was wrong, the problem was that the teacher didn't understand the whole problem.

I contend that what we have here is a lot of people who are missing parts of the equation.
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Old 07-25-11, 07:01 PM
  #38  
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Originally Posted by DiabloScott View Post
I contend that what we have here is a lot of people who are missing parts of the equation.
And a lot of you are over complicating it!

Technique, 'balls', aero profile, tubular/clincher, tyre size, rubber compound, tyre pressure, rim type, wheel stiffness, bike geometry, road surface material, road conditions, road design, clear lines of sight, weather, and more all play a factor.

However, to answer the question that was asked? Weight DOES make you descend faster. Simple.

Will taking on weight magically make you faster than the guy beside you? No - not if he's got any of the other things going for him.
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Old 07-25-11, 07:50 PM
  #39  
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Originally Posted by DiabloScott View Post
Back in the days of itinerant baseball teams, the promotors would get the local high school physics teacher to come out and discuss how throwing a curve ball was impossible because there would be no force vector on the ball after it left the pitchers hand - it could only be an optical illusion. Then they'd set up a couple tall poles and the pitcher would pitch around them in a way that proved the ball was curving. The problem wasn't that the physics was wrong, the problem was that the teacher didn't understand the whole problem.

I contend that what we have here is a lot of people who are missing parts of the equation.
hahaha
perfect
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