Suggested replacement please for weird CS20 bottom bracket

[slomo]

Scratchy bottom bracket means out with the old and in with the new
But google reveals all sorts of horror stories regarding these CS20's - thought i had better do some checking as mentioning 'standard' size/fitting and 'bicycle industry' in the same sentance just makes me PMSL.
Apart from being weird in the sense that it goes into the frame the wrong way around :? .....
This CS20 looks pretty symmetrical.
It seems the weirdness can increase with different varieties of CS20 with things like different sized spindles on the left and right side, cranks contacting the frame when a different variety used etc.....
The frame is a 92 Rockhopper.
The cranks are Exage LX500 with Biopace chainrings.

Anyone know if i can just replace this BB with a 'standard' 73 x 122.5 square taper?
Or do i really need like for like

Much appreciated.

 

[Yogi bear]

Looks to be the standard English threaded, 73mm body 123mm axle.
I cant see any issues.

 

[mynchiboy]

Re:

Looks to be the standard English threaded, 73mm body 123mm axle.
I cant see any issues.

Yep, bang on, although you'll need a 122.5 axle. The axle length is sometimes stamped onto one side of the axle, just under the cup before it meets the bearing.

The Shimano parts code corresponds to the overall quality of materials, including bearings most likely - the lower the number the lower the spec. They also were issued on groupset packages according to the level. Codes went from UN10 (Tourney level) all the way through through to UN91 (XTR Level).

I would suggest sourcing a new UN55 unit, which are readily available, well priced, a nice upgrade and should last you ages. Fit and forget

 

[slomo]

Blessed relief - many thanks
I didn't even want to start looking for a 1992 BB - CS20 :roll:

 

[hamster]

Some of the early Shimano BBs indeed had the body screw in from the left not the right, I remember one BITD...it puzzled me no end when its replacement screwed in from the other side!

 

[mynchiboy]

Re:

^ Good point, I've also had this happen to me

 

[slomo]

Yep - i've always wondered about it.
But it's been a long time since it was replaced so i just got used to it.
I googled 'replacing CS20 bottom bracket' and the first page i looked at suggested that the fact that it goes into the frame the wrong way around is (potentially) the least of your worries.
But as suggested - mine seems quite 'normal' - apart from the orientation.
Fingers crossed.....

 

[legrandefromage]

I have one of those things here and remember well when my one failed sometime back in 1993

 

[slomo]

Just to be clear.....
It failed in 1993.....
And you've still got it?

That is.....awesome! :shock:

 

[legrandefromage]

nah, not that bad, its a different BB