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From: barrys@tekecs.UUCP (Barry Steel)
Newsgroups: net.bicycle
Subject: Re: "Sealed bearings" ?
Message-ID: <5578@tekecs.UUCP>
Date: Wed, 7-Aug-85 11:32:51 EDT
Article-I.D.: tekecs.5578
Posted: Wed Aug  7 11:32:51 1985
Date-Received: Sun, 11-Aug-85 06:29:50 EDT
References: <8300005@ada-uts.UUCP>
Reply-To: barrys@tekecs.UUCP (Barry Steel)
Organization: Tektronix, Wilsonville OR
Lines: 35

>Anybody knows what 'sealed bearings' mean? How exactly are they sealed?

Sealed bearings are tapered roller bearings (like the kind you have on the
wheels of your car).  They require (almost) no adjustment and dirt can not
get into the bearing, as each one is a sealed unit.  They do, however require
special tools to service.

One the other hand, "sealed hubs" are more common and cheaper.  They consist
of a "maze" that is supposed to keep out the dirt.  They have the standard,
ball and cone bearing set up.  These should do a better job of keeping out
dirt than regular ball and cone bearings, which simply have a plastic shield
to keep out the dirt.

			|		|  <---- dirt must go through "maze"
		      | | |-----------| | |
		      |   |o	     o|   |
		   ========<=========>========  axle
		      |   |o	     o|   |
		      | | |-----------| | |
			|		|

			Sealed Hub

I have bikes with each type of bearing.  The good quality ball and cone bearings
seem to roll as well as the sealed bearings.  In rainy Portland, the sealed
bearings seem to be impervious to the wet, while the regular bearings require
more maintenance in the wet weather (no data yet on the sealed hubs).

My preference, given free choice would be the sealed bearings.  I believe
these will be standard on all *good* bikes in the future (like permanentantly
sealed bearings on cars are now).

Hope this helps,

barry steel