Bicycle Mechanics - What size bearings for 1979 Motobecane Grand Sprint?
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I'll be attempting to repack the bearings on the hubs and BB on my "new used vintage bike", I'm just wondering what sizes of bearings and how many do I need (for each hub) for this job.
Also, is this worth investing on, or do I just leave it for the LBS mechanics?
Thanks in advance!
10-06-09, 09:17 AM
Typically front hubs use 10 x 3/16" bearing balls per side and rear hubs use 9 x 1/4" bearing balls per side. However, there are exceptions so the safest thing to do is disassemble the hubs and count and measure the current bearings.
New bearing balls are very cheap so if you know how to do a hub overhaul, it's a lot less expensive to get new bearings and do it yourself. Get "Grade 25" balls if you buy new ones.
10-06-09, 09:26 AM
Courtesy of Sheldon Brown:
A steel ball that is part of a ball bearing assembly. Most front hubs use 10 3/16" balls on each side; Most rear hubs use 9 1/4" balls on each side. Most bottom brackets use 11 1/4" balls on each side.
Bearing balls are made in batches, and within a batch the size is very carefully controlled. From one batch to another, however, there can be a considerable variation in actual size of balls of the same nominal size. For this reason, balls from different batches should never be mixed in the same bearing.
Bearing balls come in several quality grades, designated by numbers. Grade 25 is the best that is available for bicycle applications. Grades 100, 200, even 300 are commonly used in bicycles.
old and new
10-06-09, 09:43 AM
It may be difficult for you to brake down the BB. As for the hub brgs., a shop should have them too. I believe the bike has standard type English threading so you shouldn't get stuck with a problem. Some LBS get anxious over working on French bikes which is understandable as the mechanics don't see French bikes frequently. Particularly the younger guys. So you can prevail upon them to help if they're reluctant at first, such situations haver happened to me.
Your bike is by and large standard in all regards.
I've only ocassionally sought out the actual balls to replce, mainly if they'd spilled out an lost or if an insufficiant amount was found out the outset. If the balls show wear, the race is compromised. One could argue that the newer balls are less worn, still round but smaller, this is true but I still prefer to get complete or just lube, depends on what's handy. BTW, shops don't tend to over-sell BBs.
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