BLYTZPK

pits suggest dirt in grease

wrong torque produces grooves. Hi torque narrow grooves, low torque wider grooves, more variation in size around the cones or base.

rydabent

Preload? Not good!!!! When the quick release is then set the bearings are being galled.

easyupbug 

While bearing overload can certainly cause galling I would be surprised to see the result being the ball track pitting the OP described. Would be interesting to see a good photo.

jsdavis

I took the bike to bike kitchen and took it apart and cleaned it out again. Cups still look good, but cones are no good.

Digging through a container about the size of a gallon milk bottle, I was able to find only two cones the correct size and taper. Suffice to say I think these hubs are not often rebuilt because they are low end even though Formula hubs are everywhere; I guess they are so cheap people don't bother with it. I put everything back together and one of the mechanics there helped with adjustment. Reflector broke off a week ago, but two cones on the valve stem cause that part to fall to the bottom of the rotation so I think it's adjusted correctly. Hopefully this time around it lasts longer - and I will not wait 2.5 years to change the grease again.

jsdavis

This is the best I can do with my point and shoot camera. Does it help? I don't have anything better.

easyupbug 

Wow, that is so far gone for a 1,000 miles if the pre-load was any where near correct and reasonably greased it would I think have to be a bad batch of cones from the factory. You should have felt side movement at the rim long before this, something to check closely with the new cones. I look over my tires/brakes etc. from time to time and in spinning the wheel would certainly have picked up this kind of condition.

Andrew R Stewart 

This looks more like fretting to my eyes. The roughened dimples suggest an erosion VS a compression. Andy.

FBinNY 

This is an example of thin case hardening which failed. Most cones are harder on the surface, then below (the core). In metal science they refer to different hardnesses as the case to core ratio.

By analogy imagine a frozen lake. The surface ice, gets little support from below, so if it's overloaded, it'll crack and break under load. the thicker the ice the more load it can support (why humans shouldn't go after dogs on frozen ponds).

In steel the under layer does provide some support if it's hard enough, otherwise the pat acts like a frozen lake. With wear the hard zone thins, and/or if the load is too high it cracks away and the load is taken by the metal below which isn't up to the task.

Looking at this, I suspect a cheap part, with a thin case, and a very poor case to core ratio. However it shows little wear, and I supect was killed off by being excessively preloaded (too tight).

One other possibility that I've seen cause similar damage is one ball too many.

jsdavis

To be honest, this isn't something I knew to check for aside from setting the cone adjustment correctly. I guess i will now. The only thing that tipped me off was that the front wheel would intermittently make a pinging sound.

jsdavis

I am not sure what you mean. Erosion meaning by contaminants grinding against this or corrosion and then the balls scrubbing the rust away?

garage sale GT

The pits caused the clearance to open up a bit, then the bearings weren't too preloaded and the bearing balls and wear particles rounded the edges of the pits.

Pitting is caused by fatigue failure. Too much preload or clearance. Dirt won't make the metal fail below the surface.

Andrew R Stewart 

Fretting is the loss of the bearing's race/cup's surface from the breakdown of the lube and then the erosion of that surface. The classic with bikes is with a headset. With very little rotation to distribute the grease and the often too high a preload (tight adjustment) the balls tend to sit on one point along the race/cup. In time the very slight movement with no lube will cause the surface to "flake" off. Many of the "brinelled' headsets that we see are actually eroded from the fretting action.

Brinnelled surfaces will have a smooth indent, as the balls are rounded in shape the compression they leave (from impact forces) are also rounded. The cone pictured has roughened pits that are spaced one ball apart from each other. Andy.

FBinNY 

The overall condition of the cones argues against rust being a factor. Go look at railroad tracks to understand why. If rust were a factor, we'd see a polished (or worn) area where the balls ran, with unremoved rust to either side.

While classic fretting is a possibility, that's a slow process, and is more common in stationary bearings (headsets). This is called a fatigue failure, which is a mechanism similar to the cracking of ice on a lake (as I described earlier). The moving local stress of the balls depresses the surface, which rebounds behind the ball. The constant movement, especially if not well supported from below flakes the meal. You can see a similar process in real time if you use a rolling pin to roll some pie crust, let it dry a bit, then try rolling some more.

jsdavis

Yes, train tracks are typically polished smooth where the wheel rolls, though other portions are a darker brown color - I roll over several sets of recessed tracks daily.

Now as for my hub adjustment, I could not feel any binding before I had the wheel in the fork. In fact there was a bit of play and the axle rotated smoothly in my hand. The play went away when I tightened the skewer and even then it was loose enough that I the reflector would pull that part of the wheel down to the bottom of the rotation. Does the condition of my cones and my adjustment still suggest the cones were too tight?

FBinNY 

Usually there's a clear wear line at the ball track before the case flakes or collapses. Not seeing that, my gut instinct is that i was a crappy cone with a very thin hardened skin, and zero core support below.

If you want, you can mail it to me, an I'll do a hardness test both on n undamaged area of skin, and then grind off a bit to test the core.

One way to tell the difference (by wear) between too tight and too loose, is the position of th ball track, but I suspect thes are too fargone for that. However tight cones wear exactly at the same ball track of perfectly adjusted cones, while cones run loose will have a wear track at a smaller diameter. Sometines the cups also give some clues.

3alarmer 

.
.
....on a side note, now that you've found the closest co-op, even if you cannot find any
suitable cones in their "can o' cones", it is often possible to find a collection of salvaged
hubs in a drawer or bin somewhere. You then find an appropriate hub (similar to yours)
and buy it for a few bucks, then strip out the axle and axle fittings, and swap them into
your hub, saving yourself the work of relacing the wheel. FYI #justincase

Kimmo

Sounds like you didn't mess it up; guess you must've been boned on the cone quality.

Anyone suggested Wheels Manufacturing yet? They make a wide range of quality replacement cones IIRC.

jsdavis

Someone posted it further up in the thread. I went to two shops that took out their Wheels Mfg Taiwanese kit, but the 9x1 cones are too tall

jsdavis

Are the parts there for sale? I saw drawers, boxes, and crates full of parts there, but didn't know if they were free or for sale. I also saw people digging around in them but wasn't really sure how it works. When I went to pay they told me the cones, grease, and ball bearings I used were free. Though I did pay to use their shop for the day.

As far as co-op, I'm still not entirely sure what this means. There are several of them in and around SF according to this site but some of them are regular bike shops as far as I can tell.

Kimmo

What, even the CN-R086?

rydabent

Let me say again the bearing on MOST bikes are not made to be preloaded. If the wheel is out in hand and preloaded, when it is put in the fork, it is compressed even more, and you will get what is pictured.

Preloading the bearing cause the thin hardened surface to deform!!! That leads to the failure shown.

3alarmer 

...it varies from place to place, which is unfortunate, but that's how it is.

Our place (Sacramento) sells parts to go out the door, as well as parts to use on your in the shop projects.

The San Fran Bike Kitchen in SOMA, when last i checked, has a rule that parts sales are limited
to in shop projects, unless you have "digging rights", which are procured in some convoluted fashion
that is specified on their website.

And some of them do seem to function more like regular for hire places, where paid staff do the work.
As opposed to educational, "do it yourself with advice from volunteer mechanics" places.


I find myself apologizing regularly for the differences, because there are so many and people don't
always understand that it's not a franchise model business. But we are the cheapest alternative.

I'd just try to call or e-mail ahead before I went very far out of my way for something.

jowilson

My 2 cents:


Since you replaced cones once because of pitting, it may be possible that the cups inside the hub were pitted slightly as well. The bearings binded and metal scraped off, caused further pitting, etc. When you had the wheel replaced to a new hub, were the bearings adjusted properly? Sometimes new hubs come over tightened and bind. You may be able to take the hub back to the LBS if it's under warranty and they'll replace what's needed. A co-op would be just as good, in fact better because you can learn how to correctly regrease and adjust a hub.

Josh

jsdavis

Am I using the word preload incorrectly? When I set the cones and locknut, there is still play in it before I insert it into the fork.

FBinNY 

OK, to try to set the record straight here.

Angular bearings, like on typical cup/cone bike hubs need to be preloaded. There are no exceptions. Otherwise the Ball track will be toward the smaller end of the cone, and there won't be constant contact. That causes the cone to try to wedge between pairs of balls when they're at the 5&7 position, then it has to move toward center to clear the ball as it rolls past 6. This cuases vibration, shock and excess wear.

Preload ensures that the ball track is at the zero clearance line so the balls at 5 & 7 support the cone at the same height as the one at 6, and all balls are in contact 100% of the time. Perfect preload is the least that will do this job, or at least well less than the bearing's rating.

Now, here's where confusion arises. The dimensions change under various conditions, so for example high sprrd spindles are set loose at room temperature, so they hit correct preload when warmed up. Bike bearings don't worry about heat, but the action of a QR skewer can compress the axle slightly, or mis-alignment of the fork ends can bow it. Either or both will tighten the bearing, so you compensate by setting it up slightly loose so that it's perfect when the wheel is on the bike.

My favorite way to determine if a bearing is adjusted correctly is what I call the Goldilocks test.
If when installed, you can feel any free play at the rim, it's definitely too loose.
If when installed, you're sure there's no play, and maybe the hub drags when coasting, then it's too tight.
If when installed, you think there may be play, but you, can't feel it clear enough to be sure, that's perfect.

I hope this helps.