[CR] BB fixed cup wall thickness

(Example: Framebuilders:Tony Beek)

From: "CyclArt Shop" <shop@cyclart.com>
To: devotion finesse <devotion_finesse@hotmail.com>, CR discussion list <classicrendezvous@bikelist.org>
Date: Fri, 27 Mar 2009 16:22:39 -0700
Thread-Topic: BB fixed cup wall thickness
Thread-Index: AcmvMiNqMibuzMyIS0aQavuFyPPDug==
In-Reply-To: <COL113-W73600557278669343943D0F58E0@phx.gbl>
Subject: [CR] BB fixed cup wall thickness


In support of my earlier post, I grabbed a few fixed cups from a box in bac k and measured wall thicknesses. I laid them outer face down on my desk, an d used a micrometer caliper's depth gauge to measure from the inner face to the desk surface. Here's what I found, in order of thickness:

Campagnolo Record (thin): 2mm TA: 2.5mm Stronglight: 3mm Tange, no seal: 3mm Campagnolo Nuovo Record (thick): 4.5mm Suntour, sealed: 4.5mm Shimano BB-7400 Dura-Ace, sealed: 5mm (Note: I removed the lip seals from the Shimano and Suntour cups to measure )

I have quite a few more cups I can measure, but from my small sample and an additional visual inspection, cups with a lip seal are always thick-walled . Those without lip seals tend to be thinner, which stands to reason.

Wall thickness may be the most significant part of the difference between c ups, but they may not be all. I also noticed that while most cups have a st ep below the bearing race, others have the race blended seamlessly into the wall. So to accurately gauge the relative bearing offset, perhaps they sho uld be measured to the top of the cage of a standard bearing set.

Greg Reiche CyclArt Vista, CA USA

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