Asymmetric - What does it mean?

[Mick F]

Here's a conundrum.

I happen to have measured some Campagnolo BBs.

I have a Mirage 111mm, a Mirage 115mm and a Chorus Triple 111mm.

The Chorus Triple is described as Asymmetric, and the Mirage's not.

The tapers stick out from the bearings by the following distances:
Mirage 111mm - Rh 18.2mm Lh 21.5mm
Mirage 115mm - Rh 20.0mm Lh 24.5mm
Chorus 111mm - Rh 18.9mm Lh 18.9mm

It appears to me that the only one Symmetrical, is the one that's described as Asymmetrical! Is there something I'm missing here?

Actually, it may not have anything to do with measurements. The Chorus has a double bearing on the Rh side and a single on the Lh side.
Is that what they're referring to?

[Steve]

Mick - I know the days are getting shorter and the nights longer but I'm sure you can find something better to do!

[Mick F]

I'm not well. Sniffles and snot and headaches - you know the scenario.
I have to do something.

Seriously though, I've finally got round to buying the correct BB for my Chorus Triple chainset. It wasn't cheap, and when I added the little tool to fit it, the bill came to over £50.

The BB is described as Asymmetric, whereas the others I've used weren't. So there was a little doubt in my mind whether it would fit or not. It fitted, of course. But I'm puzzled.

[Bob S]

A lack of symmetry. ie. eccentric

[Deckie]

No, eccentric is when an axle is offset within its bearing, such as the front BB on a tandem (or just strange!)

Could be that the designer thinks one side of the crankset takes more pressure that the other?

[Mick F]

My point is that if that what "asymmetric" means axle length with respect to BBs, then why is the only BB I have that is described as asymmetric the only one that isn't?

As I said before, my Asymmetric BB has equally sized axles, but it has a double bearing on the drive side.

So Asymmetric must have something to do with the bearings.

[Bob S]

I do not know, but could the outer case for bearings be bored out slightly eccentic to give small adjustment. you could check on V-blocks or between centre's