Bike Forums - Mixing Bearings

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I am in the process of overhauling my pedals. I opened them up and I came up two short. They must have fell on the floor. Is there a problem of using the same size from another lot?

Bearings are inexpensive. A common practice is to replace them all when the opportunity arises.

Generally, I avoid mixing. I either use the existing balls or I replace them all.

It's not the cost. I cannot buy them locally and I will have to wait for an Amazon delivery.

Quote:

Originally Posted by daniell (Post 22768439)

….I will have to wait for an Amazon delivery.

If I were in your situation on my transportation bikes I would compare size carefully and not look back because I’m too lazy to pull it apart again when the bearings arrive.

I bought a selection of balls a few years ago and I expect enough will be left that some will be an issue for the probate court.

Define "lot". Do you have a clue what the vendor sold you?

Just put them in. It's a pedal going 100 RPM with minimal load, not an F1 car

are you SURE that "two are missing" ? there MUST be space between the bearing balls for them to roll correctly...... ;-)

In answer to the OP, there is no problem mixing new balls from one lot with new balls from another lot. I might not do it in a nuclear reactor, but there is no real difference from one new bearing to another for our purposes.

Yes I am missing two. There should be 11 on each side. I have found 20. I will have to wait for the new ones to arrive after all. I need 5/32 inch. The extra ones that I have are 3/16 inch.

Quote:

Originally Posted by Kontact (Post 22769366)

^This. In high precision applications it is useful to have high precision bearings with very tight specifications. The fact that the OP is reporting missing bearings strongly suggests that he is not in that realm. Campagnolo has been rigorous in specifying high grade bearings (better than Grade 10) and the result has been very durable components with proper maintenance. The bike in general is more like Grade 25 bearings and low end components are probably more in the Grade 100 range. The OP can probably go to any local hardware or mechanical supply store and find the 5/32" bearings he needs.

No problem. When you get to it, you get to it.

If you have 7 or more bearings in each, then you'll have enough. But get a full set to put in there when you can. However you can button it up and still ride today if you hurry. The only thing about using the other bearings is bearings are something that need to be within a few 10,0000ths of each other or else the larger ones are the only thing bearing the load.

Quote:

From: jbrandt@hpl.hp.com (Jobst Brandt)
Newsgroups: rec.bicycles.tech
Subject: Re: How Bearings are Made
Date: 22 Nov 1999 23:05:20 GMT

Roger (who?) writes:

> Did you know you should only ever use ball bearings from the same
> batch in one side of a race? They're not exactly the same size
> between batches. Never simply replace that naughty one that bounced
> into the corner of the garage - replace the other 10 (or whatever)
> too!

You are making this up. The tolerance between bearing balls is so
small as to be below a small fraction of the elastic compliance of the
steel bearing. Besides, the races of bicycle bearings are so rough
that a tight bearing feels lumpy. In high precision bearings used on
computer disk storage devices, preload causes a smooth viscous drag.
Even for these bearings the balls are not identical but are made to a
prescribed tolerance. I don't believe I understand what you mean by
the same batch. Each bearing is not made in the same finishing
process as the others in a shipment of balls.

Jobst Brandt <jbrandt@hpl.hp.com>

Quote:

One of the reasons why I suggest routinely replacing the balls is that it is very easy to fall to see pitting or crud on a ball, since you can't be sure that you have seen every side of it. When I am repacking a hub, if I drop one of the new balls on the floor, I don't even bother to pick it up. I use another new one rather than contaminate the bearing by putting in a possibly dirty one.

It is particularly important that all of the balls in a given race come from the same production run. They are made to tolerances of 3 or 4 millionths of an inch. One batch may be oversize, while the next batch may be several millionths undersize. If some of the balls in a race are that much smaller than others, the smaller ones might just as well not be there, because only the larger ones will be taking the load.

-Sheldon Brown

One of them was an engineer and the other one sold ball bearings, take your pick.

In modern mass production what is even a "batch"? Who documents and tracks it, much less how and where it is divided up in the supply chain.

I found the missing balls on the floor. The pedal is now reassembled. Contrary to the advice on You Tube videos, I picked up the bearings with a magnet.

Quote:

Originally Posted by daniell (Post 22770823)

I found the missing balls on the floor. The pedal is now reassembled. Contrary to the advice on You Tube videos, I picked up the bearings with a magnet.

Wait are people saying to not pick up bearings with a magnet on the youtubes? Sometimes those places can be a cesspool. Steel bearings are perfect for being picked up by a magnet. I would probably clean them which I would be doing anyway but magnets to pick them up are a fine choice.

Quote:

Originally Posted by veganbikes (Post 22770966)

They argue that the balls will become magnetized and then pick up metal shavings.

The deal with magnets and bearings is that the now magnetized balls will attract metal grit and shavings. IME, it's a non-issue with bike parts but with my old 14k rpm racing motorcycle engine I stayed away from picking up small engine bits with a magnet.

Quote:

Originally Posted by daniell (Post 22771015)

They argue that the balls will become magnetized and then pick up metal shavings.

Ok that makes a small bit of sense but not enough to really worry about it.

Quote:

Originally Posted by Soody (Post 22770150)

One of them was an engineer and the other one sold ball bearings, take your pick.

Sheldon Brown was a lot more than a ball-bearing salesman. :innocent:

Quote:

Originally Posted by sweeks (Post 22777696)

Sheldon Brown was a lot more than a ball-bearing salesman. :innocent:

Yeah, he was the man, and i've learnt and continue to learn a lot from his excellent website and writing.

Someone who doesn't sometimes spout nonsense probably isn't very interesting.

Quote:

Originally Posted by daniell (Post 22770823)

I found the missing balls on the floor. The pedal is now reassembled. Contrary to the advice on You Tube videos, I picked up the bearings with a magnet.

I use a magnet all the time to pull bearings out of hubs/head tubes/freewheels/etc when cleaning and re-greasing. I should probably stop now because everyone knows that everything you read online has to be factual. Right?
And I should add, when fixing bikes for free that aren't worth the cost of the parts combined, I RE-USE old bearings from other bikes. Close enough for a bike that probably won't be ridden more than 2 miles in the next century but will be left outside in all kinds of weather.