Balancing wheels?

[BHOFM]

Is balancing wheels necessary? Or is my engineering back ground getting in the
way?

I ended up with 1/2oz on the front and 3/4oz on the rear to get near perfection.
I did three spins to stop in both directions and they never stopped twice in the
some spot.

Most of my riding is under 30mph. My average is just over 14mph.

 

[dhk2]

It must be an engineer thing. When I got my new bike years ago, I noted the wheels were out of balance when fine-tuning the shifting on the repair stand. (The seat shook very noticeably when the rear wheel was spun up to 25 mph). Surprisingly, I had to add weights right next to valve stem. Believe this is due to the weight of the steel pins used to join the rim 180* opposite. I sometimes have to readjust the weights slightly to maintain balance when changing tires.

As I said, it must be an engineer thing. Several people have asked me about the weights, and when I explain what they do, I generally get a non-response back. Some have tried to argue that (unlike a car) we don't go fast enough on our bikes to notice the out-of-balance condition. I point out to them that we routinely exceed 40 mph on local descents, and that I like to have my wheels firmly planted on the road for max grip at high speed. Besides, I routinely have the wheels rebalanced on my cars because out-of-balance is very noticeable to me, even on a heavy vehicle with springs and shocks to dampen out vibration.

 

[alfeng]

Is balancing wheels necessary? Or is my engineering back ground getting in the
way?

I ended up with 1/2oz on the front and 3/4oz on the rear to get near perfection.
I did three spins to stop in both directions and they never stopped twice in the
some spot.

Most of my riding is under 30mph. My average is just over 14mph.

Okay, here's the non-engineer's point of view:

While balancing the wheels probably has some benefit (I presume you did this with the tire/tube in place AND you are not using a SLIME-type sealant which sloshes around in the tube with each rotation) ...

AND, while someone else can calculate the RPMs which a 700c wheel is turning at about 30 MPH ...

I'm just going to ballpark the RPMs as being under 360 @ 30 MPH ... I think you might have to triple-or-quadruple your wheel's RPM before the typical imbalance (whatever THAT might be) is felt on the typical (whatever THAT might be) roadway would be noticed.

So, I'm going to say that there is NO benefit to balancing your wheels other than whatever therapeutic value the manual endeavor imparts while you are doing the balancing ...
​

Of course, SOMEONE ELSE may have a different opinion with regard to the value of (statically) balancing a bicycle wheel the way you have, and s/he may be right!?!

 

[alfeng]

Let me add (and, you can take this as just 'my' opinion) that I think that an eccentric wheel, or one that wasn't laterally true, OR comparatively loose or unevenly tensioned spokes will have a greater negative effect at cycling speeds than the imbalance you observed.

 

[BHOFM]

One of the concerns I had was that the rear wheel when the bike was inverted for
service, was spun fairly fast would cause the bike to almost jump off the table. Now
it doesn't even move.

Tire is 80.6" circumference.

At 30mph the wheel is at 393.05rpm.

5280X12=63,360/80.6=786.1 (for 60mph)/2=393.05

It is Sunday, it is hot, the shop is cool and I have nothing better to do.

 

[Resistorlead]

I think unbalance is detectable when riding and I usually wind a short piece of plumbing solder around a spoke to balance a wheel. I also like 'em running true!

 

[BHOFM]

Let me add (and, you can take this as just 'my' opinion) that I think that an eccentric wheel, or one that wasn't laterally true, OR comparatively loose or unevenly tensioned spokes will have a greater negative effect at cycling speeds than the imbalance you observed.

Your opinion is important to me.

I have checked the wheels for run-out and straightness, they are "on the money"!
I have thumped the spokes and they all sound true.

Being an old pilot, the first thing I did when I got the bike was to tear it down and
check all the bearings and fasteners. It was new from Wal Mart and already put
together. Wal Mart here does not sell boxed bikes any more.

Thanks to all that replied.

 

[BHOFM]

I think unbalance is detectable when riding and I usually wind a short piece of plumbing solder around a spoke to balance a wheel. I also like 'em running true!

I used 1/4oz split fishing weights.

 

[dhk2]

alfeng, agree that wheel and tire roundness are important to a smooth ride as well; balance by itself isn't enough. But disagree that the rpm's of our wheels are too low. Besides, I hit 38-42 mph every day coasting down my home hill, which is over 500 rpm.

BHOFM, your observations match mine. People have argued that it doesn't matter if the seat vibrates 1cm vertically at the "one per rev" frequency because their body damps it out and their butts aren't that sensitive anyway.
It's just strange to me that people believe they can feel the difference in frame materials, tires or pressures, yet think that they would't detect imbalance in their wheels.

As I said, it must be an engineer thing. My best riding buddy thinks I've fussed over nothing, and that doesn't bother me at all. He also doesn't believe it's important to re-balance and rotate his truck tires periodically; that the tire companies and installers are just out to make extra money when they recommend that service every 5-6K miles and sell the "lifetime rotate and balance" packages for a few extra bucks a tire.

 

[64Paramount]

I used 1/4oz split fishing weights.

Good idea!

 

[alienator]

I've never balanced a bike wheel and have never had any issues, even on fast descents (60+ mph). That history spans a lot of different wheels: deep CF rims, boutique wheels, custom built wheels, low spoke count wheels, high spoke count wheels.

Of course, you have to do what makes you feel comfortable.

 

[tafi]

We discussed this a while back. I did some calcs and found you would have to be doing several hundred km/h before the wheel would be spinning fast enough to make the bike loose contact with the ground.

The bike would physically have to lift off before the rider can feel any effect.


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