Surprising

A couple days ago, I bought a Park Tool BBT-5 cassette lockring tool. It claims to fit all Campagnolo lockrings.

Uhhh… no.

I have two Campagnolo lock rings. One came with my 13-29t cassette and the other came with my rear hub. I can’t remember which one came with what now but here they are.

The splines are different on the two lock rings.

Different.

The tool fit the right lock perfectly but it wouldn’t go into the left one at all. I measured the distance from a protruding spline down to the opposite protruding spline on both lockrings. There was a difference of 0.07mm which is about 2.7 mils – or about the thickness of a sheet of paper.

Different.

Now that doesn’t seem like a lot for a difference but it was enough for the tool not to be able to fit. I wondered if the lock ring was out of round. Nope. I wondered if the tool was out of round. Nope.

2.7 mils!

I ended up filing the splines down in lockring number two by about 0.09mm.

I can't believe I'm filing a Campy part!

Would you believe it that now the tool fits?

Fiat used to sell cars in the US before pulling out in the 80s with a notorious reputation for poor quality. Remember the old slogan of “Fix It Again Tony”? Could it have happened because of 0.07mm difference between designed-as and built-as?

Yikes!