I’m running a non boost rear wheel in a boost frame (Orange clockwork evo) with equal spacers either side of the hub.

Recently fitted a 46T cassette replacing a 42T, this amplified my poor chainline, but managed to make it workable by adjusting BB spacers, bringing chainring closer to the frame.

I’ve just swapped front chainring to an oval 34T which touched the chainstay, so I’ve adjusted the BB spacing again to suit, which has made the 46T noisy again. I managed to get a spacer behind the cassette which made it a bit better.

Visually, the chainline looks bad in the 46T and its makes a lot of noise of the bike stand. I think the noise is coming from the jockey wheel interface. It doesn’t drop the chain if pedalling backwards.

Rear hub is a fairly new DT Swiss 240 laced into a DT XR391 rims.

The only way I can see to improve it would be to get a slightly smaller spacer on the DS and a bigger one on the NDS, perhaps going from 3:3mm to 2:4mm, any bigger and I don’t think I’d be able to adjust the brake enough. But that would likely only make a small difference

Should I worry about it?

Solution seems to be a new rear hub?

It doesn’t drop the chain if pedalling backwards.

Well, that’s better than on my ‘proper’ Boost setup SRAM Eagle 12spd, then.

It’s hard to get a feel for how much of an issue the noise is. IME all 1x setups*, the large sprocket is a bit noisier than in the middle of the cassette. If the gears all index fine and it’s not something bad (E.g. the chain is catching the derailleur cage), then it might just be something you can live with?

As you say, the only ‘proper’ solution is a new rear hub and that might not even fix it completely to your satisfaction if you’re super fussy. But on the other hand, if it sounds like a bag of spanners then maybe it does need something more.

*I’ve had 1×10 Shimano, 1×11 Shimano, 1×11 SRAM and 1×12 SRAM over the years.

Solution seems to be a new rear hub?

You could also try a hub adapter kit which puts all of the spacer on the NDS (requires redishing and rotor spacer). That way the cassette is still in its original position relative to the dropout / BB and hence the chainline should be as intended (if the BB spacers are correct).

Thanks for replies. Seems like it might be sensible to take the rotor off, put both spacers on the NDS and see if I’m happy with how the gears are then, before getting too excited about doing anything else.

You could also try a hub adapter kit which puts all of the spacer on the NDS (requires redishing and rotor spacer). That way the cassette is still in its original position relative to the dropout / BB and hence the chainline should be as intended (if the BB spacers are correct).

If I dont re-dish the wheel, just use a rotor spacer and all spacers on NDS, presumably that just means that my rear wheel is 3mm off centre? How much of a difference can 3mm make, considering tyre is ~60mm?! I guess its easy to try and see before going to effort of getting wheel redished.

Just space the nds and redish the rim, will take about 20 minutes.

Yep, space it over with no spacer on the drive side and dish your wheel across to suit. Anything else will just be a bit poor.

Thanks guys.

There is a kit that boosts 240s properly. It’s not cheap but after a redish your issues is solved.

https://www.tredz.co.uk/.Wolf-Tooth-Boostinator_217915.htm

DT ratchet rear version

Just took the rotor off, moved both spacers to NDS and redished it. Took about 1 and 1/4 turns to get there, much more straightforward than I expected.

Chainline is much better, but still a bit noisy in the 46T. Think it might be related to chain tension rather than chainline, but still a better set up now.