Wheel balancing weights?

Fredrico · Sep 25, 2016

JCavilia said:
We have two subjective accounts from non-blinded uncontrolled experiments in which riders say they could perceive a subtle effect that they expected to perceive. This last guy says his bike rode smoother than his friend's bike. Were the bikes identical but for the tiny weights?

Contradictory statements in the same sentence.

We have nothing but wishful thinking. We should call it "placebo balancing."

Well ok, can you feel the modulus of elasticity of a nice steel frame from the harsher stiffness of a carbon or aluminum frame?

It's like listening to music. The experience is more pleasurable when the third harmonics are faithfully reproduced!

Lombard · Sep 25, 2016

JCavilia said:
We have two subjective accounts from non-blinded uncontrolled experiments in which riders say they could perceive a subtle effect that they expected to perceive.

Ahhh, blindfold riding test! Wouldn't that be interesting!

MMsRepBike · Sep 25, 2016

JCavilia said:
We have nothing but wishful thinking. We should call it "placebo balancing."

Again, I have the new Silca weights and they're installed correctly on a set of my wheels. When spinning the wheel and letting it rest on it's own, it picks a different spot each time, it's fair to say they worked in balancing out the wheels. Before they would always rest valve down.

Now... how do they feel? They don't. How do they work? They don't outside of what I said above. Am I faster? No. Is descending more stable? Not that I can feel. Are there any real tangible benefits? Not that I can make out.

I'm the perfect test subject I would think. High speed descending right? Can't feel a damn thing. They succeeded in making my bike heavier, I can assure you of that. They succeeded in "balancing" out my wheels, that's for sure. That's all though.

Kerry Irons · Sep 26, 2016

Fredrico said:
Well ok, can you feel the modulus of elasticity of a nice steel frame from the harsher stiffness of a carbon or aluminum frame?

It's like listening to music. The experience is more pleasurable when the third harmonics are faithfully reproduced!

We all know that you really want to believe this balancing nonsense. But it is not true.

And your frame reference simple goes to point out that you don't understand the interactions of materials and design. CF or Al frames are only "harsher/stiffer" if they are designed to be. It's NOT about the modulus of elasticity of the metal.

Superstitious belief is not how engineering progresses.

cxwrench · Sep 26, 2016

Fredrico said:
Well ok, can you feel the modulus of elasticity of a nice steel frame from the harsher stiffness of a carbon or aluminum frame?

It's like listening to music. The experience is more pleasurable when the third harmonics are faithfully reproduced!

I guess you've never ridden an old Vitus or a Calfee carbon frame. As Kerry posts, it's not about the material but how it's designed/used.

Marc · Sep 26, 2016

Fredrico said:
Well ok, can you feel the modulus of elasticity of a nice steel frame from the harsher stiffness of a carbon or aluminum frame?

It's like listening to music. The experience is more pleasurable when the third harmonics are faithfully reproduced!

This had better be a troll...because it is getting damn funny.

Fredrico · Sep 27, 2016

Kerry Irons said:
We all know that you really want to believe this balancing nonsense. But it is not true.

And your frame reference simple goes to point out that you don't understand the interactions of materials and design. CF or Al frames are only "harsher/stiffer" if they are designed to be. It's NOT about the modulus of elasticity of the metal.

Superstitious belief is not how engineering progresses.

Of course it is. It all adds up. Builders have tried to make aluminum and carbon "feel" as comfortable as steel. 20 years later, they're still trying. They failed. So now we've got "elastomer shocks." Gosh, I wonder how those work?

Bikes are manual instruments intimately connected to the rider. Everything: construction materials, shapes of tubing, geometry, handlebars, drive train components and wheel bearings, determines the quality of the ride. We may agree rim weights might be taking things a bit too far, but it all adds up to a certain ride characteristic, whether by design or luck. Great bikes do everything well. Average bikes do some thing well and others not so well. So I'm not going to write off rim weights. Two posters have said they can feel the difference. I responded that "feel" is so subtle, it's hard to put in words.

We had this problem discussing aerobic vs. anaerobic muscular performance, as it determines power and endurance, the most basic skill we all go after as enthusiastic riders. Everything relates and contributes to the workload in constantly changing parameters. How it all adds up is the challenge. So many of you guys just throw up your hands and say, "Let's not confuse the issues! Just ride!"

Fredrico · Sep 27, 2016

Marc said:
This had better be a troll...because it is getting damn funny.

Hey, I'm glad somebody got it!

jjaguar · Sep 27, 2016

Most likely the reason the rim seam is opposite of the valve stem is so that they are drilling a hole through the rim as far away as possible from a joint, for strength.

FWIW, I balance motorcycle wheels on a static balancer, which is basically a rod on bearings with a couple of centering cones. You give the wheel a light spin and an out-of-balance wheel will always stop with the heavy side down. When the wheel is in balance, it will stop in a different, random position each time. I suppose you could use a similar technique to check the balance of a bicycle wheel, but it's never occurred to me to even try. If it made a real difference, you would see the pro peloton use wheel weights on the bikes they use for mountain descents, at least. Do they? I don't think they do, but I really don't know.

Fredrico · Sep 28, 2016

cxwrench said:
I guess you've never ridden an old Vitus or a Calfee carbon frame. As Kerry posts, it's not about the material but how it's designed/used.

Vitus were flippy back in the 80s, but they were aluminum frames, with oversized lugs and 1" top tubes, 1 1/8th down tubes, that fit the same jigs as the steel frames. I've heard the Vitus lugged carbon bikes LeMond rode were maybe a little lighter than steel but performed as well. By today's carbon standards, they were probably stiffer, but the skinny 1" tubing probably absorbed shocks satisfactorily, despite the stiffer tubing.

It took Cannondale 10 years before they got the nerve to skinny down their fat tubing for fear the stuff might tear apart from torsional flex. Manufacturers also put alloys in aluminum tubing to give it a greater "modulus of elasticity," mainly as a safeguard against breaking rather than shock absorption and rider comfort. That would be handled by the tires and forks. Tubbies give such a nice ride! And they stuck with steel forks 10 more years after aluminum and carbon frames came on.

Calfee and Colnago have stuck to skinny tubing and lugs to absorb shocks like steel. Chinese carbon frames all have really skinny seat stays to absorb shocks. Don't have to go pencil thin with steel and it's thus stronger and more durable.

So I must disagree that a good builder can make any material, steel, aluminum, or carbon, ride the way he designs it. The first parameters are in the tubing choice, the second, in the geometry. These determine the personality of the bike. The wheels and drive train dress it up, but don't change this personality.

Ask any builder what he thinks of steel, aluminum, carbon? It's very difficult to engineer aluminum or carbon to equal the combination of response and comfort that comes naturally in 1" steel. Sure, builder can screw up with steel, but designers of carbon and aluminum have to jump through hoops and still can't get it quite right compared to steel.

The subtleties of the machine are a nice part of riding. Don't knock it! Wheel balancing weights? Sure, if it floats your boat!

cxwrench · Sep 28, 2016

jjaguar said:
Most likely the reason the rim seam is opposite of the valve stem is so that they are drilling a hole through the rim as far away as possible from a joint, for strength.

FWIW, I balance motorcycle wheels on a static balancer, which is basically a rod on bearings with a couple of centering cones. You give the wheel a light spin and an out-of-balance wheel will always stop with the heavy side down. When the wheel is in balance, it will stop in a different, random position each time. I suppose you could use a similar technique to check the balance of a bicycle wheel, but it's never occurred to me to even try. If it made a real difference, you would see the pro peloton use wheel weights on the bikes they use for mountain descents, at least. Do they? I don't think they do, but I really don't know.

^This This This^

mfdemicco · Sep 29, 2016

My Shimano wheels are balanced. Shimano put a weight opposite the valve stem integrated with the rim. They don't even advertise this as far as I know, but I tested it and the wheel is balanced. Hmmm...

What about balancing low pressure gravel, touring, or mountain bike wheels? Would you feel difference at high speed? Don't know, but I suspect you could, depending on the degree of imbalance. 50 psi for the gravel/touring bike, 25 psi for the mountain bike.

TmB123 · Sep 29, 2016

Do you know what length valve stem they allow to offset?
the other thing, seeing how they already drill through the rim (and remove material in doing so) to accomodate the valve, there is already some missing weight that side of the wheel.

Fredrico · Sep 30, 2016

jjaguar said:
Most likely the reason the rim seam is opposite of the valve stem is so that they are drilling a hole through the rim as far away as possible from a joint, for strength.

FWIW, I balance motorcycle wheels on a static balancer, which is basically a rod on bearings with a couple of centering cones. You give the wheel a light spin and an out-of-balance wheel will always stop with the heavy side down. When the wheel is in balance, it will stop in a different, random position each time. I suppose you could use a similar technique to check the balance of a bicycle wheel, but it's never occurred to me to even try. If it made a real difference, you would see the pro peloton use wheel weights on the bikes they use for mountain descents, at least. Do they? I don't think they do, but I really don't know.

The pros ride what their sponsors give them. The captains can dicker about stuff like geometry, gears, handlebars and saddles, but they probably haven't demanded balanced wheels. Some of their wheels are balanced to being with. They could probably care less about wheel weights.

However! Check the picture below, skeptics! :yesnod: Shimano engineers think this little weight, smaller than a dime, finesses the wheel in perfect balance. Other rim makers probably also do that, if Shimano does.

So there ya go. You guys better get hip.

cxwrench · Sep 30, 2016

They're not 'balanced' just because there is a bit of weight somewhere. There just happens to be a weight opposite from a hole. Whether they're actually 'balanced' is something else entirely.
If the weight of the weight(!) is equal to the weight of whatever valve you happen to use minus the weight of the material that used to be the valve hole, then you're balanced.

Mike T. · Sep 30, 2016

cxwrench said:
They're not 'balanced' just because there is a bit of weight somewhere. There just happens to be a weight opposite from a hole. Whether they're actually 'balanced' is something else entirely.
If the weight of the weight(!) is equal to the weight of whatever valve you happen to use minus the weight of the material that used to be the valve hole, then you're balanced.

You and I know bike wheel balancing is bollocks. For there to be a felt vibration, the force of the oscillation would have to overcome the tire pressure and compress the tire - or lift the bike and rider. A car's suspension is more easily overcome by the oscillation because the amount of unbalance will probably be far greater than a bike tire and the speed greater - plus with a car we're talking (approx) 30psi pressure and <60mph> oscillation speed. Car tire imbalance is rarely felt at slower speeds

The car's tire has much greater relative "width" to a bike tire and if the heavy spot was away from the center line of the car tire, it would oscillate back & forth thus giving the characteristic shimmy that indicates a tire out of balance. That's why car tire balancing machines (I balanced thousands of tires when I was an auto mechanic) tells us where on the rim the weigh goes and whether it's on the outside or inside of the rim - or both sides equally.

Fredrico · Sep 30, 2016

Mike T. said:
You and I know bike wheel balancing is bollocks. For there to be a felt vibration, the force of the oscillation would have to overcome the tire pressure and compress the tire - or lift the bike and rider. A car's suspension is more easily overcome by the oscillation because the amount of unbalance will probably be far greater than a bike tire and the speed greater - plus with a car we're talking (approx) 30psi pressure and <60mph> oscillation speed. Car tire imbalance is rarely felt at slower speeds

The car's tire has much greater relative "width" to a bike tire and if the heavy spot was away from the center line of the car tire, it would oscillate back & forth thus giving the characteristic shimmy that indicates a tire out of balance. That's why car tire balancing machines (I balanced thousands of tires when I was an auto mechanic) tells us where on the rim the weigh goes and whether it's on the outside or inside of the rim - or both sides equally.

That's interesting a car tire shimmies because it's out of balance on one side only. If it's out of balance on both sides in the same place, it hops, right?

Bike wheels are going to be out of balance only vertically. So they won't shimmy, but "hop," vibrate uncertainly on the road, subtly loading and unloading the tires, making the tire slightly less firmly planted on the tarmac. My friend told me he noticed the smoothness on very smooth pavement, less so on bumpy pavement. It's very subtle.

mfdemicco · Sep 30, 2016

Fredrico said:
That's interesting a car tire shimmies because it's out of balance on one side only. If it's out of balance on both sides in the same place, it hops, right?

Bike wheels are going to be out of balance only vertically. So they won't shimmy, but "hop," vibrate uncertainly on the road, subtly loading and unloading the tires, making the tire slightly less firmly planted on the tarmac. My friend told me he noticed the smoothness on very smooth pavement, less so on bumpy pavement. It's very subtle.

I have felt road wheels bounce slightly on a smooth road when the tire was slightly out of round.

Fredrico · Sep 30, 2016

mfdemicco said:
I have felt road wheels bounce slightly on a smooth road when the tire was slightly out of round.

So have I with a badly repaired tubular tire.

Those old fashioned round wheel reflectors used to make the wheels pulse slightly and you'd notice it around 18 mph. Of course, those things were considerably heavier than a valve stem, and also whacked the air coming in from the front.

Lombard · Sep 30, 2016

mfdemicco said:
I have felt road wheels bounce slightly on a smooth road when the tire was slightly out of round.

Out of round is not the same as out of balance.

Wheel balancing weights?

Fredrico

Lombard

MMsRepBike

Kerry Irons

cxwrench

Marc

Fredrico

Fredrico

jjaguar

Fredrico

cxwrench

mfdemicco

TmB123

Fredrico

cxwrench

Mike T.

Fredrico

mfdemicco

Fredrico

Lombard

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