Bicycle Mechanics - Overtightened hubs?

I brought my beater bike in for a tune up. It rode fine when I brought it in, and dude said I would need new rims soon, but in the meantime, he tightened the hubs. But now, the wheel feels "knocky" when it rides. Could it be that the hubs are overtightened, or are my wheels just that bad? :-/

Koffee

If they feel knocky they are either usually loose, or the seam of the rim is smacking the brake pad on every revolution. If they feel gritty, or like there is a vibration caused by grinding then they may be overtightened. Quick way is to give your wheel a spin and see how long it goes. When the wheel starts to come to a stop, it should roll back in the other direction a bit.

I check for grit in the bearings such as your 'grind' by spinning the wheel and holding the frame right next to the axle. Generally if it has grit you will feel a slight vibration.

This guy is really very thorough. How would grit get into the bearings? I mean, with all that goop and new bearings, plus a tightened hub, grit would really make the wheel feel all wobbly like that when I'm riding?

Koffee

Sometimes the balls can wear unevenly or rough, which does not become apparent until it is disturbed by rebuilding. There are ways to correct that, I'm not going to go into the details since they are really not doable without the bearing tools. To check for bearing loosness, just grab the wheel and push it side to side while holding the frame. If you feel a tap, or really anything other than the wheel turning, the bearing is loose. Either condition, loose or tight, is bad in the long term.

Dang it... and I dont' have the tools to fix it myself either. I'll do a check on it in the morning (got the laptop and laying in bed), and if that's the case, I'll bring it back in. I'm sure he'll fix it right up.

Thanks everyone!

Koffee

Anytime

Dang it... and I dont' have the tools to fix it myself either. I'll do a check on it in the morning (got the laptop and laying in bed), and if that's the case, I'll bring it back in. I'm sure he'll fix it right up.

If you have that much confidence in your mechanic, it sounds like pitted cones to me. That'll give you the choice of either hubs that are a little bit loose or else hubs that feel a little gritty.

(got the laptop and laying in bed)

Such dedication to the forum... wow.

Seriously.

Good luck with the wheel, hope you sleep well.

it sounds like pitted cones to me. That'll give you the choice of either hubs that are a little bit loose or else hubs that feel a little gritty.

I'll second that. Especially if it is a beater bike that has not had a lot of TLC.

What are pitted cones?

I only ride the bike in the winter, and I thought I had it tuned up at the end of winter. Then again, I just can't remember for sure.

Somehow, I think this bike is done for. I might just strip it for parts at the end of the winter or something. Or maybe just strip it to the frame and take it with me when I move. I have two other good bikes to work with.

Koffee

The cone shaped nuts that hold the ball bearings in place have become pitted from either rust or excessive wear.
Just remove one and check it to be sure. There should be an even, thin, shiny wear line around the perimiter of the cone. If the line is wide (50% or more of the ball diameter) or has several pits or scars then the cones require replacement.
(~20 minute job to dissassemble check and replace)
Enjoy

Pitting is little etched lines in the channel (race) the bearing is running in.
It's from the bearings brunelling (denting\ un-rounding) lack of lubricant.

A cone is a hub bearing race. Race is refered to in loose ball bb's and headsets.

I might be wrong. Never fixed one.

To quote from the mechanics book on my desk: ;)

Pitting is small hollows of irregular shape in the surface, usually caused by corrosion or mechanical chipping of the surfaces.
Pitting in a hub would most likely happen if the bearing was left to sit for a long time with bad lube or lube that had water contamination in it. Chipping forces happen when there is grit such as sand in the grease.

Brinelling is one or more indentations on the bearing races usually caused by high static loads or application of force during installation/removal(mainly on cartridges). Indentations are round or spherical due to the impression left by the contacting balls or rollers of the bearing.
For the bike application, brinelling occurs when the bearing is set too loose and impacted(such as trails would).
I don't want to offer any conclusions since I can't see the peice, but thats the definition of the day. :)

I totally didn't have the time to check, but tomorrow, I have to do all my bike-related errands. I'll try to get over to the LBS tomorrow.

Thanks everyone!

Koffee

http://www.ebearing.com/glossary/b.html

Bottom: false brinelling.

Touche`
I like your source better, but this book is what the FAA made me learn with :rolleyes:

Nope i'm off.

http://www.timken.com/products/bearings/services/valueadd/prevent.asp

I thought brinelling WAS a deformation of the ball. Incorrect.
I confused this with Brinell ball hardness test.
Pitting would be irregular race surface from wear. Brinelling.
False brinelling would be wear marks from shock\no lube\ stationary or irregular bearings.

I think...

Correct on the false brinelling. I thought we were referring to the races not the balls. Oval worn balls is really easily fixed though. Bicycling Magazine's manual details the procedure for resetting the oval balls if not replaced. For as little as new balls cost it really would be a hassle to do so though.

All you old schoolers with loose balls...

Get your balls checked. ;)

False brinelling is preventable.

a summary:

The grooves the bearings run in (races\cones) are worn 'brinelling' normally.
False brinelling occurs when bearings are>

:worn\irregular balls
:stationary\no lube
:undue stress\shock

Some of this is preventable, bearings need to be inspected\ replaced in>

:hubs
:headsets
:loose ball bb's
:non-sealed bearing system pedals

All these systems need regular cleaning\ lubricant re-packing.

This will decrease both the effects of brinelling and the occurance of false brinelling. :)

precisely why you should never let the bike sit! ;) Run 'em and maintain 'em.

The latter you mentioned(being stationary) is actually the number one bearing problem in the aircraft hangar. Planes are build to withstand massive loads, but they generally sit idle for extended periods. Once a bearing has done that beyond a certain extent, we are not allowed to legally put it back in.

Brinelling (true or false) should not be a problem with hub bearings. In hub bearings everything is constantly moving so the balls cannot pound against the cones or races in the same spot over a long duration. Hub bearing wear is usually seen as roughness of the cones and balls. Bike hub races usually do not show these signs as they are a harder material and very long lasting.

On a bike, you generally have brinelling problems with headsets since they spend most of their time in the same position and the balls do not get repositioned relative to the races.

Thats why headsets always get 'spun' when I do rebuilds for people. I've seen it mentioned in a few places, and it works pretty well.

Brinelling (true or false) should not be a problem with hub bearings. In hub bearings everything is constantly moving so the balls cannot pound against the cones or races in the same spot over a long duration.
I disagree with that assertion. The cones being dented or Brinelled is caused by the instantaneous impact that a loose or overloaded bearing would have. If the bearing is impropperly tensioned then it is prone to this. What I see most in cones is not the false brinell, which is evidenced by a discoloration of the surface of the race, rather it is true brinell.
If there is any brinelling in the hub race it would be false brinell. That is caused by static corrosion. True brinell, while possible, is unlikely due to the increased contact area of the outer race.

I had true brinelling in my loose ball bb.

Koffee...just walk up to the mech and say "I need my balls pulled out and inspected." :roflmao:

Possibly..if...you over-tightened..AND if you didn't lube, it might cause false brinelling.
Tightening would not be the same as pulling the hub..ones a 'job' other is maintenance =meaning the inspection -replacement\grease packing is a service fee.
Tightening is a service inside the maintenance run.
Perhaps you've just found a new thing to maintain\ fix (replace bearings)..or the nuts were clamped, maybe no grease.
they should be inspected -cleaned regularily.
If the cones have fresh marks\scratches into the races, the tightening probably did it?

I use an areosol 3 in 1 white lithium grease to clean and regrease bearings.
(it foams out grit, settles leaving grease).

Any opinions on effectiveness?? (new idea). seems to be working o.k.

I wish the SunTour Greaseguards were still around. A grease fitting on a hub was so cool.

There's just something about a hand in a tub of moly grease that feels good :D Does wonders for the skin too.

Thanks for the debate. I needed to refresh the memory after finals week :)