It’s all just maths, folks – put in which ever assumptions take your fancy and see how it comes out 😛

I’m not trying to prove anything – just curious to see how the numbers looked, but bear in mind –

Full body weight on a crank in 24:36 means mashing up a 1 in 1 (i.e 100% gradient) hill on a 26″ wheel, and even then, you’d only see that torque stalled with the pedal at the 3 O’Clock position – if you’re still moving forwards, the torque will be lower.

In more realistic gears (say 32:28) the torque on the cassette is much less – it would need a 140kg / 22 stone rider out of the saddle up a 1 in 2 (i.e 50% gradient) hill to reach the ~230 Nm at the cassette;

Wear comes about from things that happen repeatedly. If a sprocket slipping is marginal in a one off, worst case scenario, then it’s unlikely to happen repeatedly in “normal” riding and hence unlikely to be the cause of wear.

FWIW, I use a torque wrench, because I don’t trust myself. I tend to be a bit ‘agricultural’. My baseline is the rear hubs on bay window VW busses – 340Nm (bent a 3/4″ drive tommy bar!).

Working out the rough figures above has convinced me that I should make sure to give it enough beans when tightening the locking ring – YMMV 🙂

“Torque figures for bike components are very often a maximum measurement,”

Not really. Ime they are optimistically under speced or totally irrelevent – ie handlebars with torque values.

If the lockring is insufficiently tight the different parts of the cassette can move independently so the load is not spread and the cog that’s being driven by the chain is the only one pressing into the freehub, this is when it can mash the freehub body.

The sprockets also bend if the lock ring is not tight enough. I have an odd shape XT cassette from not having tightened the lock ring properly.

It’s one place that torque doesn’t really matter that much. I’ve had a lockring loosen up once, and apart from a bit of a rattle and perhaps less than perfect shifting, I wouldn’t have noticed. Was a bit surprised as I always thought it didn’t need to be tight at all, since then I’ve given them a bit of grunt.

Even a one-piece cassette digs into freehub bodies under tandem torque, I have my doubts that tightening more would help much. Just tap with a hammer (or whatever comes to hand), no real problem.

Good thread.

My hunch is that lots of people don’t apply enough torque and lots of people moan about the cassette mashing the freehub body. Go figure