Crankset wobble

JVB · Post by **JVB** » 20 Aug 2007, 11:22am

I've changed my Campag crankset for a Shimano Deore - both square taper. The leftside crank has a bit of play. I can tighten it so that the play disappears but this pushes the crank up against the BB causing it to rub. It either needs a different BB (with a marginally bigger taper) or a shim. Does anyone have any bright ideas about the material to use as a shim so that the crank doesn't become stuck?

Post by **Mick F** » 20 Aug 2007, 11:43am

Mixing BBs and cranks isn't a good idea. Shimano and Campag have the same taper angle (I think), but are of different lengths - hence your problem.

I suggest you get the right BB. I know that a shim might work, but for the low cost of a BB, I don't think it's worth it.

JVB · Post by **JVB** » 20 Aug 2007, 11:54am

Thanks Mick - a very clear and straightforward answer. I was looking at the Sheldon Brown website while you were replying - it amplifies exactly what you said - don't mix the Japanese and the European, particularly Japanese cranks and European BBs.

hamster · Post by **hamster** » 29 Aug 2007, 5:10pm

Shimano and Campag DON'T have the same taper. Campag needs a finer taper and mixing them in my (bitter) experience is a recipe for the crank falling off and being subsequently unusable.

Crazybiker · Post by **Crazybiker** » 29 Aug 2007, 9:32pm

The tapers are different. As you have found, you can torque the crank down enough to take the 'apparent ' play out, but this is still not a proper fit in engineering terms - thrashing uphill maysoon have the crank 'creeping' on the taper, which is only really fitting properly over a fraction of it's surface. In a battle between the alloy crank and steel axle the axle will win every time.

This is a shame, because if it were just a case of sorting out the clearance it is easy to do. You need a shop that deals with hub gears, especially the old Sturmey Archer ones. The shimming spacers used on the sprockets to adjust the chainline are a perfect fit on the BB.

But personally I wouldn't risk it.

ianr1950 · Post by **ianr1950** » 30 Aug 2007, 9:10am

The angle of taper is the same but it is where the cut off point is that makes the difference.
As Mick says for the price of a new BB its better to do that.

Sorebutt · Post by **Sorebutt** » 2 Sep 2007, 10:47am

If you are going to use a shim I'd suggest cutting out a piece of tin or aluminium from either a food or drinks can (pref alu), both materials are sufficiently malleable to work without damaging the existing parts, a non-metal shim would be a non-starter - but again if you afford a matching set, so much the better.