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I'm a bonehead(7 posts)

I'm a boneheadcrestlinefarm
Jan 24, 2004 8:02 PM
I'm out in the shop tonight repacking the bearings in my "classic" Euro bike. I pull the fork out and realize (too late) that the ball bearings in the bottom of the fork cup are loose! The top bearings were politely contained in a cage, when I lowered the fork out of the head tube and a herd of 26 tiny balls escaped and rolled to the farthest, deepest, darkest, and dustiest corners. Unfortunately, I only found 25.
My first question, is it possible that I bought the bike with only 25? Would you even notice a missing bearing? I mean it's a 1" threaded fork so we're talking a bunch of very small bearings.
My second question, should I reassemble it with only 25? Should I try to find a match (I read somewhere that a "close-but-no-cigar" bearing can cause trouble)? Should I replace all 26--or should I try to find a politely caged bearing that fits the cup?

arrrrrrrrrrrrrgh.....
re: I'm a boneheadrussw19
Jan 24, 2004 9:29 PM
Put a bead of grease in the cup so the bearings stick and then put all the balls back in. They should be close together but not quite touching. If there looks like there is not quite enough room to squeeze in one more, then you only had 25 to begin with. If there is more than one balls width left, you need the 26th. If that is the case, I would simply take one back out and go to either your LBS or a bearing shop or a very good hardware store. If you go to an LBS, they most likely would have higher grade bearings in stock, but are more likely to charge more than a bearing shop or hardware store. But, if you go to a bearing shop or hardware store, make sure you get Grade 25 bearings. That is what Campy's and Shimano Dura-Ace's bearing quality is. The lower the number, the better. The absolute worst you should settle for is Grade 100. But you might as well do it right and get good bearings.

Russ
Good Advise - also replace the entire setbimini
Jan 25, 2004 4:44 AM
Bearings coming from the same lot will be all the same nominal size within a few millionths (at grade 25). The nominal size betwen lots can varry quite a bit. A single bearing could be larger or smaler than the rest. If it is larger it could cause damage to the races.
What makes you think there were originally 26?Spoke Wrench
Jan 25, 2004 5:15 AM
If you didn't make a point of counting when you disassembled the bearing race, whether it's a headset, hub or whatever, it's kind of hard to tell how many were there before. The rule of thumb is that if it looks like there is room for just one more, you've got the right number. Lots of times it's hard to tell where the bearings actually roll in the race so your trial fit may have a smaller or larger "bearing circle diameter" than will be the case in actual use.

At this point if it was my bike it would depend on the situation. If I wanted to ride it tomorrow, I'd assemble it with the 25 bearings I had and not worry. Sometimes when you do that, however, you might have to readjust the bearing preload after the first short ride so be sure to check it. If I was doing a winter overhaul, I'd leave it until I could buy all brand new replacement bearings.
I see a trip to the LBS in my future...crestlinefarm
Jan 25, 2004 9:51 PM
This is for a winter project. I tried checking to see if I should have had 25 or 26 by placing the 25 in the cup and on the race, and sure enough there was room for "unlucky #26" on both.
I've decided to either replace all the bearings, or replace with a caged version, depending on what the LBS has in stock. I found standard loose ball bearing sizes, such as 1/8, 5/32, 3/16, 7/32, and 1/4--what size would I need for a 1" threaded fork--geometry was sooo long ago! Alternatively, are 1" caged bearings pretty standard? Unfortunately the closest bike shop to me hasn't proven overly technically capable, yet they seem to have a good selection as long as you know what you need.
Take a sample or two with you.Spoke Wrench
Jan 26, 2004 5:41 AM
If you're anything like me, they all look to be about the right size unless I have a sample for comparison. This is a case where close in size really doesn't cut it.
I believe that it should look like there is room for one more...TFerguson
Jan 26, 2004 12:08 PM
as the above poster states. I know I was fooled the first time I took apart a front hub. Luckily, I could just go to the Shimano site and look it up.

TF