Wheel out of balance? I need some expert advice!
 

This is a problem that has been bothering me all summer and I can't take it anymore.
When my bike is up on a stand or otherwise suspended the freewheel of my rear wheel makes a peculiar oscillating noise. Rather than the expected "rrrrrrrrrrrrrr" it sounds like "rrrrrRRRRRrrrrrRRRRRrrrrrRRRRR" (please forgive the strange means of expressing that sound). The freewheel is loud and the difference between that and every other bike I've had is unbelievably dramatic. This simply cannot be right.

Furthermore— when breaking at lower speeds the brake force oscillates at a period consistant with wheel RPM. I'm sure it happens at higher speeds as well, but it is more perceptible when going slowly. That does not in anyway inspire confidence.

The last time I was at my LBS (without my bike on that occasion) I mentioned the sound and the mechanic to whom I spoke told me that every freewheel had its own particular sound that that I probably shouldn't worry. I'm thinking about bringing it is soon-- and I hate to be a PITA-- but I feel I have to.

I thought that the wheel might have been out of balance but I made sure that the magnet was directly opposite of the valve stem, so there's not much more I can do.

I'm posting this inquiry so that I might better able to speak intelligently regarding the matter when I drop it off. Does anyone have any wisdom they could share? Please???? And thanks!

Wheels: Bontrager Aeolus 5 TLR clinchers. Shimano Ultegra CS-8000
Rim brakes, not disc.

Bring it in to the shop. I'm (pretty) sure there's nothing at all wrong with it, but having a shop mechanic check it out will give you some piece of mind. I've heard hundreds if not thousands of hubs do this over the last 25 years and it's never a problem.

Wheel balance is irrelevant on a bicycle wheel. Does it make noise when you are riding it?

What rear hub do you have? Whether you have a freewheel or free hub, some make different sounds both in volume of sound and seemingly the oscillation of the sound. What you describe sounds like what I percieve as a normal DT Swiss free hub sound.

As for brakes pulsing, a wheel needing truing, a seam in the rim, a bend in the rim. That needs some decent eyes on it. My son had a rim taco on him at speed around a curve simply because he thought dad's advice to check his wheels every so often was silly.

If you don't know what to look for, then let someone else with experience look. Take it to an LBS for a checkup and tune up. Don't let them just do it and then give it back to you. Ask them questions so you can get some experience from them just like you can get some here.

I wouldn't worry about the hub noise.
Note where the wheel "offends you". Look at that spot on the rim that is touching the brake shoes at that time.
It's not rocket surgery. It's paying a little bit of attention.
You are there. We aren't.

The undulating sound pattern is not universal, but certainly not unusual - I've had freehubs and freewheels do it, others not. For wheel balance, remove the magnet, put the bike in a stand and give the wheel a spin. Note where it settles. Repeat a couple of times to ensure that it settles at the same point, then reattach the magnet to a spoke opposite the low point . The magnet may not perfectly balance the wheel, but it'll mitigate the imbalance as much as is achievable. If you want to get really weird, rotate the tire by maybe 90 degrees and repeat the spinning expt (with the magnet in place) - there might be a spot where any imbalance in the tire cancels out any imbalance in the wheel (at this point, the wheel won't coast to a stop at a single consistent point, or will oscillate widely and slowly around a single point). Of course, this finding will only apply to that tire, and your tire logo will likely not align with your valve - an offense far worse than any free hub noise or wheel imbalance :innocent:. Ride unaligned at your own risk.

Also, threaded freewheel hubs will have a degree of wobble due to the fact they are threaded, and it could also be that your wheel is not perfectly round, but has a high or low spot vs being true to the brake pad. This will create a degree of imbalance. I believe cassettes don't suffer the same imbalance/wobble as they are not threaded on.

If your road bikes wheels have reflectors they will likely be the source of imbalance. With reflectors on a light road wheel set this can be felt by lifting the rear wheel off the ground and giving the wheel a brisk spin by pushing down on the pedal. Remove the reflectors and try again and you will feel the imbalance is gone.

I had a road bike with reflectors that created a very noticeable and unnerving out of balance at higher speeds, such as rolling down a hill. I added a second reflector on the opposite side to balance it. Later on, I bought some decent lights and removed the reflectors.

I'd be more worried about the brake pulsing and its worth having your LBS check that out as a potential safety issue. They can look at your noise while they've got it. If the noise is driving you nuts ask what they would charge you to replace the freewheel.

Put your bike on a bike stand. Watch the valve stem as the front wheel comes to rest. If you have a wheel magnet on your front wheel, take it off. Knowing nothing about your bike, my bet is that your valve stem will stop near the top making that the lightest part of the wheel.

Brake "pulsing" can be a sign that the rim is wearing thin on a localized part of the braking surface. Eventually the rim's wall can break off causing anything from a minor nuisance to a major catastrophe. This process can progress pretty quickly because every time the wide spot passes through the brakes, the rim is flexed as it is compressed against the tire's air pressure. On the rim below, when I noticed the bulge (before riding home from work), I lowered the tire pressure by about 50% and didn't use the rear brake.

Locate the area where the brake is binding and inspect both sides of the rim very carefully for cracks running along the circumference of the rim. If you see them, you're on borrowed time... replace the rim.


https://cimg4.ibsrv.net/gimg/bikefor...aa39b9a0fe.jpg
Brake track wear approaching failure.


https://cimg5.ibsrv.net/gimg/bikefor...f57e68b27e.jpg
Radial view of cracked rim displaced by tire pressure. This rim was thumping during braking.

Freehub and freewheel noises vary from hub to hub. Generally, the more expensive aftermarket wheelsets will have a louder ratchet sound. Shimano, which are the highest quality hubs in my opinion, often have very quiet or almost silent freehubs, probably due to the thick grease they use during assembly.

When a freehub starts to fail, you might notice a difference in the ratcheting sound. It will go from 'ZZZZZZZZZZZZZZZ...' to 'ZZZcrunchZZZZZZcrunchZZZ...', usually with the crunch occurring once per revolution. Some aftermarket hubs allow maintenance of the gubbins inside the freehub, while others, like Shimano, are designed for freehub replacement rather than repair.