[CR]Cartridge Bearings


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From: BobHoveyGa@aol.com
Date: Thu, 24 Jun 2004 12:42:56 EDT
Subject: [CR]Cartridge Bearings
To: classicrendezvous@bikelist.org, Carb7008@cs.com


In a message dated 6/24/04 11:36:43 AM, classicrendezvous-request@bikelist.org writes:


> This question has been bugging me and this knowledgeable list undoubtedly
> knows the answer.  Since I play with almost exclusively vintage lwts, I had
> no
> experience with cartridge bearings until I got this Ral Pro which had a new
> Shimano cartridge bb installed.  Very smooth and zero play granted, but it
> has
> more drag than my meticulously adj bbs. This reminded me of my long-standing
> question:
>
> Do racers use low viscosity grease or even heavy oil to reduce drag?  If
> grease, why put oil holes in hubs and other bearing areas up until (a couple
> of
> decades ago) ala Campy Record hubs.  Isn't it an advantage to oil bearings
> every
> race day as opposed to fighting viscous grease?  Are contemporary racers now
> using cartridge bearings?
>

To the best of my knowledge, nearly all if not all racers these days are using cartridge bearings. Some of the tightness you're noticing is not the viscosity of the grease, but the friction of the seals. The first Phil Woods BB I got back in the 70's seemed VERY stiff, but it was just the friction of the rubber seals. After a while, the seals wore a bit and the BB spun much more freely (though never as easily as the original Stronglight). Likewise, the new (off-topic) Chorus hubs I just got seem to have seals in them (even tho they are regular cup and cone designs) and they too are a bit hard to spin. About the only sealed bearings I've ever come across that seemed to spin (almost) as freely as unsealed bearings were Weyless hubs which used a very thin seal of teflon-impregnated cloth. They not only put very little pressure on the bearing race when new, but they wore very quickly (thus destroying some of their sealing propertites, but they still kept out most of the dirt) and so would spin even better after a very short break-in period. But no matter what the material, as long as a seal is in contact with the inner race and one of the two is moving (the seal in the case of a hub, or the race in the case of a BB), there's going to be significant drag and you're not going to see any of that glorious free-spinning action (unless you've got something to act as a flywheel, like a rim and tire).

I guess the best seal design would be the labyrinth seal (Maxicar?), where dirt is kept out by thin intereaved washers that do not actually touch. No contact, no friction, just a torturous zig-zag path that only the most determined dirt particle could navigate.

Bob Hovey
Columbus, GA