Professional Cycling For the Fans - Taking on extra weight to descend faster

I wonder if any TdF rider has taken on a waterbottle filled with rocks or other such heavy objects to help them descend faster, and toss it at the end of the descent. Might be a good 'tactic' for some of the lighter climbers.....

I suspect that the amount of weight that a rider could actually attach to the bike in a brief few seconds is too small to make a significant difference.

Jean Robic was supposedly handed lead-filled 'water' bottles at the summits of some climbs to be able to descend faster.

I suspect that the amount of weight that a rider could actually attach to the bike in a brief few seconds is too small to make a significant difference.

It depends on what they put in the water bottle. A bigger factor is whether the puny arms of a climber could handle such weight.

Jean Robic was supposedly handed lead-filled 'water' bottles at the summits of some climbs to be able to descend faster.

Thanks for that fine example. That's exactly what I was wondering, ie, if it's ever been known to be done.

They won't descend faster due to being heavier. Gravity is gravity. I expect this to be refuted hotly. Hum. (They will achieve a higher terminal velocity but I doubt they reach that kind of speed!!)

They won't descend faster due to being heavier. Gravity is gravity. I expect this to be refuted hotly. Hum. (They will achieve a higher terminal velocity but I doubt they reach that kind of speed!!)

Terminal velocity is when the force of the wind and road friction slowing you down equals the force of gravity speeding you up (ie you are no longer accelerating) - and it happens on virtually all descents to all riders. Heavier riders have a higher terminal velocity - they DO descend faster. The lead bottle (actually I think it was shot pellets in the bottle) idea works, but it's not a huge factor.

The descents are already so fast that if you don't touch your brakes you often go into the corners too hot. A lot of the riders just have very little experience in handling corners at high speed. Maybe some of the teams should hire a motorcycle racer as a consultant to give them a few lessons.

Yup I know the terminal velocity definition, I just really didn't think riders hit it. But if you know better, which I have no doubt that you do, then I bow to your greater knowledge Sir!

Yup I know the terminal velocity definition, I just really didn't think riders hit it. But if you know better, which I have no doubt that you do, then I bow to your greater knowledge Sir!

Maybe you just need to ride with some fat guys to observe this phenomenon in person. ;)

Descending is a combo of skill, psychology, courage, gravity and other parameters. In my view, even if you wear a jersey made of lead, you only cover one aspect. And it can even be dangerous, if you are descending way faster than your skill level.

They won't descend faster due to being heavier. Gravity is gravity. I expect this to be refuted hotly. Hum. (They will achieve a higher terminal velocity but I doubt they reach that kind of speed!!)

Yahhh right. Try to convince me of that when clydesdales almost always pass me on descents.

Maybe you just need to ride with some fat guys to observe this phenomenon in person. ;)

Maybe he's one of those fat guys, and never sees anyone go faster than him....

haha this one I can gladly refute myself.

Extra weight would throw them off balance and probably make them slower in the long run I would think.

Extra weight would throw them off balance and probably make them slower in the long run I would think.

Yeah maybe it would help on descents that are very mild technically - with no significant braking sections - just a flat out -4% gradient downhill or something - while not being worth it because of the problem it would cause on the seemingly more typical twisty descents? Just a guess.

yeah, gravity effect is minimal. what it does do is increase inertia. once going the bike doesn't want to slow down and will go thru the air better. that has some impact on cornering too, the bike wants to turn less the heavier it is. if the weight is below the center of gravity it would tend to stabilize, if above to de-stabilize.

They won't descend faster due to being heavier. Gravity is gravity. I expect this to be refuted hotly. Hum. (They will achieve a higher terminal velocity but I doubt they reach that kind of speed!!)

It's true, weight doesn't matter for gravity. Light and heavy fall at the same rate unless effected by wind resistance or other forces. So the bigger guy actually has slightly more wind resistance. But the extra weight does give him more inertia which can help to maintain high speeds over slightly changing pitches. But, as has been pointed out being able to brake quickly is very important on steep twisty roads and the lighter guys can brake more quickly. So it's kind of a trade off. Having more nerve, daring and bike handling skills seems to be more important than weight for descending.

Another issue is strength. The big guys can usually output more wattage for short durations on the downhills to get their speed up. So if they have the nerve and the handling skills combined with their greater inertia they can really fly on straight downhills with varying pitches. On steep curvy stuff the lighter guys seem to have an advantage. Not only can they brake easier but they can accelerate faster coming out of the curve. And because they have less inertia they can corner faster without crashing since inertia tends to want to keep going in a straight line. So it seems that in the end things come out rather even for descending and races are only occasionally decided on the descent.

actually gravity is computed by mass, not weight. but adding lead weights does add mass, so for common understanding they are about the same. However, more massive objects do fall faster than less massive objects. It's just that the formula for gravity is computed between 2 objects and includes both masses (the object in question and the earth) and the earth's mass is so much greater than the lighter object's mass (be it a feather, cannon ball, bike and rider or whatever) that the difference in gravitational force between the earth and these different objects is negligible. Further, with any resistance (like falling through air) that effect is much greater. gravity is actually a pretty weak force. even a small magnet can overcome it. Pick up a paper clip with a magnet and it's overcoming the entire force of the earth-paper clip gravitational force.

I agree that extra weight won't improve a rider's speed on the descents, at least for the pros.

Basically they're going so fast that descending is all about handling skills and getting aero.

For example, look at Christian Vande Velde's power chart from Stage 14. Change the elevation to "time" and you'll see that his power output drops significantly, and often to zero, on the descents.

http://connect.garmin.com/activity/99936583

Extra weight isn't going to help them around corners, and that seems to be where the biggest difference is between riders.

Put them all on a straight line decent, and they're all within a couple of seconds of each other.

I love when people give their opinions on science.

They tried that with Jean Robic in the early postwar years.

I love when people give their opinions on science.

The problem is that the real world is complicated. A real situation isn't just going to match up with one law of physics. Going downhill, the big boys go faster. There are a variety of reasons for this, but whatever reasons people to chose to cite won't effect the reality of it.

The problem is that the real world is complicated. A real situation isn't just going to match up with one law of physics. Going downhill, the big boys go faster. There are a variety of reasons for this, but whatever reasons people to chose to cite won't effect the reality of it.

Good Lord...

Good Lord...

My point is that you are oversimplifying it. Different scientific laws are going to contradict each other in this.

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.

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...

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!

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.

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

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.

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.

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.

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.

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.

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.

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.

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