Bottom Bracket Cup Differences BB-633 vs BB-631

After removing the bottom bracket cups on my old Schwinn World bicycle
(spindle is 124.5 mm (3S) type) I found the cups look just like the
ones labeled BB-651 on the following YST product page. I came by a set
of BB-633 cups and bearings on the same YST page.

http://www.yst-corp.com.tw/bycicle3.htm

The BB-633 seems to fit fine, except the fixed cup stands out about
1/16"-1/8" further than the BB-633 type. I did a test fit of the
crankset and everything seems to clear so the standout seems ok..

My question is this. Other than the obvious difference in wrench types
to remove the fixed cup (I used Sheldon's homemade bolt and nut fixed
cup remover for that anyway), and the amount the BB-633 stands out,
is there any difference in these cups and bearings? Does anyone know
what they mean by the term, "U-type chain case," used to describe the
BB-633?

What does CP-UCP mean?

Is one better than the other?

smyrna45 wrote:

After removing the bottom bracket cups on my old Schwinn World
bicycle
(spindle is 124.5 mm (3S) type) I found the cups look just like the
ones labeled BB-651 on the following YST product page. I came by a
set of BB-633 cups and bearings on the same YST page.

http://www.yst-corp.com.tw/bycicle3.htm

The BB-633 seems to fit fine, except the fixed cup stands out about
1/16"-1/8" further than the BB-633 type. I did a test fit of the
crankset and everything seems to clear so the standout seems ok..

My question is this. Other than the obvious difference in wrench
types to remove the fixed cup (I used Sheldon's homemade bolt and
nut fixed
cup remover for that anyway), and the amount the BB-633 stands out,
is there any difference in these cups and bearings? Does anyone know
what they mean by the term, "U-type chain case," used to describe
the BB-633?

What does CP-UCP mean?

Is one better than the other?
CP = good chrome plate
UCP = bad chrome plate

On Thu, 05 Aug 2004 01:51:47 -0400, smyrna45
wrote:

Does anyone know
what they mean by the term, "U-type chain case," used to describe the
BB-633?

A chain case is like a chain guard, but encloses the chain completely
(top and bottom runs). MODEL SBHCC - 294 (FULL GEAR CASE) is shown at
http://www.safaribikes.com/mud.htm

I'm guessing here, but a U-type chain case may have a bracket that
installs using part of the fixed cup.

On Thu, 05 Aug 2004 18:00:04 -0500, dianne_1234
wrote:

On Thu, 05 Aug 2004 01:51:47 -0400, smyrna45
wrote:

Does anyone know
what they mean by the term, "U-type chain case," used to describe the
BB-633?

A chain case is like a chain guard, but encloses the chain completely
(top and bottom runs). MODEL SBHCC - 294 (FULL GEAR CASE) is shown at
http://www.safaribikes.com/mud.htm

I'm guessing here, but a U-type chain case may have a bracket that
installs using part of the fixed cup.

Thanks Dianne. I bet you are right about the chain case. The fixed cup
on the BB-633 has a extra set of threads beyond its lip, which jut out
another 1/8" to 3/16" or so. This would be a perfect place to attach
that enclosed chain guard with a hole big enough to slip over it.
Probably why they provided another lockring too for the fixed cup
side.