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Road Cycling “It is by riding a bicycle that you learn the contours of a country best, since you have to sweat up the hills and coast down them. Thus you remember them as they actually are, while in a motor car only a high hill impresses you, and you have no such accurate remembrance of country you have driven through as you gain by riding a bicycle.” -- Ernest Hemingway

Body Weight Distribution?

Old 06-29-11, 03:41 PM
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SactoDoug
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Body Weight Distribution?

Does anyone know how the body weight is distributed on a bicycle at the five contact points: 2 hands, 2 feet and butt?

Every time I do a search for weight distribution it gives front/rear tire distribution which is 40/60 or 45/55. I am interested for ergonomic concerns.
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Old 06-29-11, 03:44 PM
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Shimagnolo
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Get a floor scales and an equal height block for the other wheel, then measure it yourself.
The size of the frame makes a difference;
The taller the frame, the more the saddle is shoved back toward the rear axle, putting more weight on the rear wheel. I measured one of my (very tall) road bikes, and had a 33/67 distribution.
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Old 06-29-11, 03:47 PM
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this is all bs guessing but:

(this is all flat ground cruising on the hoods. It'll change when on a curvy descent in the drops)
not much on the hands. If there's too much there, it's a problem. Maybe 5-10%
while pedaling I'm probably putting 25-35% on a leg at a time (maybe 1-2% being pushed around by the other leg when on the backstroke), although when hammering it's more like 60%
that leaves 55-70% on my butt.

anyone want to refine my numbers?
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Old 06-29-11, 03:54 PM
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Originally Posted by SactoDoug View Post
Does anyone know how the body weight is distributed on a bicycle at the five contact points: 2 hands, 2 feet and butt?

Every time I do a search for weight distribution it gives front/rear tire distribution which is 40/60 or 45/55. I am interested for ergonomic concerns.
And now this one will too.........

Originally Posted by Shimagnolo View Post
Get a floor scales and an equal height block for the other wheel, then measure it yourself.
The size of the frame makes a difference;
The taller the frame, the more the saddle is shoved back toward the rear axle, putting more weight on the rear wheel. I measured one of my (very tall) road bikes, and had a 33/67 distribution.
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Old 06-29-11, 04:05 PM
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My butt tells me that it's carrying more of the weight than it should be!
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Old 06-29-11, 04:12 PM
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Since your two hands and two feet should roughly bear the same weight as each other, as a practical matter there are three contact points.
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Old 06-29-11, 04:21 PM
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You should have very little weight on your hands. Support your upper body with your core, not your shoulders.

Distribution between your feet and your rear end depends on how fast you want to go. More power to the pedals means less weight on your rear end.
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Old 06-29-11, 04:29 PM
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Originally Posted by Shimagnolo View Post
Get a floor scales and an equal height block for the other wheel, then measure it yourself.
The size of the frame makes a difference;
The taller the frame, the more the saddle is shoved back toward the rear axle, putting more weight on the rear wheel. I measured one of my (very tall) road bikes, and had a 33/67 distribution.

That is exactly what I am not looking for.

I specifically stated that I don't want front/rear weight distribution. I am looking for hands/feet/butt weight distribution.

Fictitious example: Hands: 30# 17.6% Feet: 60# 35.3% Butt: 80# 47.1% for a 170# rider
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Old 06-29-11, 04:33 PM
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Originally Posted by SactoDoug View Post
That is exactly what I am not looking for.

I specifically stated that I don't want front/rear weight distribution. I am looking for hands/feet/butt weight distribution.

Fictitious example: Hands: 30# 17.6% Feet: 60# 35.3% Butt: 80# 47.1% for a 170# rider
Well in that case, the answer is there is no answer to your question. The weight distribution between the points you mention is not fixed and is changing throughout the course of a ride. Simple example: Standing to stretch much weight on hands, riding no hands 0 weight on hands. Weight varies continuously between these extremes during the course of the ride. Similarly for feet and butt.
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Old 06-29-11, 05:37 PM
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Studies on saddle pressure indicate that 45 - 50 % of bodyweight is on the saddle, depending on riding style (sitting up > tucked) and on power output. Note that the power outputs in the study were 100-200 watts and that doubling the power output caused a 10% change in saddle load.

The standard body segment mass distribution analyses used by physios ascribe 16% of bodyweight to each leg, it's probably not too inaccurate to ascribe all that load to each pedal. Again the pedal load will increase with increased pedalling power but the differences aren't huge.

The above leaves about 20% unaccounted for and 10% on each hand seems about right.

Another way around the problem would be to do a full segmental analysis, I might do that this afternoon if I get time.

Last edited by Mark Kelly; 06-29-11 at 05:48 PM.
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Old 06-29-11, 05:39 PM
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Originally Posted by asgelle View Post
Well in that case, the answer is there is no answer to your question. The weight distribution between the points you mention is not fixed and is changing throughout the course of a ride. Simple example: Standing to stretch much weight on hands, riding no hands 0 weight on hands. Weight varies continuously between these extremes during the course of the ride. Similarly for feet and butt.

I understand that weight shifts during riding and different positions. I am looking for an average, if such numbers exist.
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Old 06-29-11, 05:40 PM
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Originally Posted by Mark Kelly View Post
Studies on saddle pressure indicate that 45 - 50 % of bodyweight is on the saddle, depending on riding style (sitting up > tucked) and on power output (reduced saddle load with increased power).

The standard body segment mass distribution analyses used by physios ascribe 16% of bodyweight to each leg, it's probably not too inaccurate to ascribe all that load to each pedal. Again the pedal load will increase with increased pedalling power but the differences aren't huge.

The above leaves about 20% unaccounted for and 10% on each hand seems about right.

Perfect! That is exactly what I am look for. Thanks.
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Old 06-30-11, 04:23 PM
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That article on saddle pressure is very enlightening. It breaks down the saddle into three pieces, anterior, left posterior, right posterior. That breakdown makes sense.

The weight distribution is:

Hands: 10% each
Feet: 16% each
Anterior Butt: 28%
Posterior Butt: 10% each cheek


Using my roughly 200# of weight, my distribution would be:

Hands: 20# each
Feet: 32# each
Anterior Butt: 56#
Posterior Butt: 20# each

The number that concerns me the most is the Anterior number since that is the most weight but also the smallest area that it is distributed. It looks like there is only 3-4 square inches of area that the weight is distributed over. For someone of my weight, that is about 14-19 psi of pressure in some very soft tissue. If I raise the nose up on my saddle and increase the surface area by 1 square inch, that will drop the pressure to 11 psi. I would like to drop it below 10 psi.

Looking at it from the pressure standpoint, a saddle with a groove is superior to a saddle with a cutout because the groove can still support weight while a cutout obviously does not. My current saddle has a cutout. I might have to look at different saddles but at least I know what I am looking at now.
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Old 06-30-11, 04:54 PM
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You take pressure off the soft tissue by *lowering* the nose of the saddle.
That shifts it onto the sit bones.
SMP recommends their saddles be set somewhere between level, and nose lowered up to 20mm.
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Old 06-30-11, 05:27 PM
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I've tried that. It shifts more weight to my hands and made the pain worse. I suspect it is because the shift of weight to the rear of the saddle was not enough to offset the decrease of surface area at the front. The decrease of surface area increases the pressure and the pain.
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