nirakaro wrote: ↑9 Oct 2021, 12:30pm
andrew_s wrote: ↑9 Oct 2021, 12:17pm
If you follow Shimano's recommendations, and tighten your cassette lockring to 40 Nm, in the absence of a torque wrench (which those of us brought up on steel bikes commonly don't have), you look at the spanner (25 cm), do a little mental arithmetic, and say "pull hard enough to lift 16 kg" (or 35 lb if you are an imperial dinosaur).
Returning to the original question, how would you apply that to a quick-release skewer? Alternatively, how would Mr. Shimano have you apply a torque wrench to a QR skewer?
40Nm, incidentally, seems a huge torque to apply to a cassette lockring, unless it's for a serious athlete. I've always done mine up to finger-tight-plus-a-little-bit, and never had a problem.
You apply a torque to the QR by making the same calculations as I did. It's only a rough indication of how tight is suitable, as indicated by the fairly wide range originally quoted.
As for 40 Nm for a lockring, that's what Mr Shimano prints on them.
It's tighter than I would use too (I judge by the number of clicks on the ribbing), but I use a steel freehub body, so the fact that the load on the freehub body isn't properly shared between the individual sprockets doesn't matter all that much.
If you use an aluminium freehub body, and don't torque up the lockring fully, you'll find that the edges of the sprocket splines get embedded into the edges of the freehub body splines, and it's difficult to get the cassette off even after the lockring is removed.