Bicycle Mechanics - Cones
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View Full Version : Cones
10-26-01, 06:56 PM
I'm overhauling the hub on my project bike and noticed some pitting on the cones. No problem I think, I head down to the bike store with one of the cones to get a couple of new ones. But no, It seems Shimano has used something like 5million different cones throughout the years.
I should be able to get some replacements, but one of the mechanics mentioned something about polishing the pitts out by mounting the cones to a drill press and using some steel wool on them. Has anyone done this or have details on this procedure?
As mike says the pitting shouldn't make too big a difference, but if you want to try to polish them use a 400 Emorey Cloth -not emory paper which is more common. The cloth will form itself around the radius of the cone and polish it, as well as remove the flaws in the surface. For best results the cone should be spinning rapidly. It's really more work than it's worth though.
10-26-01, 09:25 PM
Steel wool isn't going to remove any material and that is what it's going to take to remove pits. It should polish them up though.
10-26-01, 11:11 PM
Haven't tried that but I had a bottom-bracket that I was cleaning and re-packing on my old bike that had some rust and pitting on the bearings. I flushed all the grease from them and then held them to the brush side on my bench grinder. It cleaned and polished them nicely. I repacked the grease and reinstalled them thinking it would be great but felt little improvement when I spun them. Wouldn't hurt to try though. At least until you can find new ones. Good Luck! DG
The worst thing that is going to happen if your cones are bad is that your bearings will wear faster. You can replace all the bearings in your hub for around $1.00~$2.00.
It will cost you more than that to replace the cones IF you can get the correct cones.
Unless you are an extreme high performance rider who might notice the minimally greater resistance due to the imperfect cones, I say use the cones as is and change your bearings every 4,000 miles or so.
Your cones and cups should be of harder material than the bearings so there is little concern that the cone damage will be transferred to the cups.
10-27-01, 01:14 AM
REPLACE THE CONES AS SOON AS POSSIBLE!!!!!
You may get a few miles on your wheels, but any time you get "pitting" on your cones, your hubs are on their way to self destruction. If you mix new bearings and pitted cones there WILL material worn away due to friction and heavy wear at the damaged areas and the metal shavings will pitt your hub races, sometimes very quickly. The next step in the Self Destruct process is pitting on your bearing races. Unless you have Campagnolo hubs, that have replaceable races, your are risking having to buy a new hub and re-lace your wheel. I've seen too many wheels "go south" from people trying to "get a few more miles" on pitted races.
I almost had to walk a long way home a few years back from "trying to get a few more miles". By the time I got home the wheels would barely turn, and the cones where ruined. ( I had to buy new hubs and rebuild the wheels, or did I have to buy new wheels?).
If you MUST use the pitted races, position the pits on "top".
You can sometimes "polish" the pits out, but if they're very deep or if you're not extremely careful, you can have "fit" or uneven wear problems. Cones usually cost less than the time and trouble it would take.
Is getting a few more miles on some obviuosly damaged, (probably fairly inexpensive), cones worth risking your hub?
10-27-01, 09:12 AM
I agree with Pat, pitted cones are the root of all evil. Getting replacement cones of the same type from Shimano can be a drag, but as long as the thread is the same, most cones will work. The seal may not be as good, and you may have to ditch the rubber ring to make them fit, but they will work.
Good quality cones are much better than cheapo ones.
With quality hardened steel cones, how deep does the hardening go. I know with some engineering components, if you file or machine away at the surface you reveal the softer metal below.
11-28-01, 03:50 AM
Here's a tip: It's not crucial you get replacement cones of the same height as the old ones,shorter ones can be packed out with spacers to match your dropout width!. But what you should check for is the size/curve of the bearing faces : pack your cups with fresh grease then place the appropiate sized bearings in the cups 3/16 x 10 out front , 1/4 x 9 out back and then place a new cone in the middle of the bearings , it should sit snug with no rocking side to side , if it sits to proud, the bearings will run on the cones thin edge and as a consequence wear very rapidly !, what you're aiming for is the bearings to run in the middle of the cones bearing face..
12-02-01, 04:51 AM
Caution, the bearings are not always 3/16 or 1/4 (but most are)- match what you have
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