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Upgraded from 3x9 to 1x12 and encountered the problem with cassette touching spokes.

Cassette-spoke interference is barely noticeable it touches spokes ever so slightly only when bike is tilted particular way. I assume the freehub body has a little bit of play / float which is normal under other circumstances. The interference is absolutely minimal. Anyway, I am trying to solve this problem.

Obvious thing to do is to stick a spacer between the freehub and the cassette. I have tried 1mm spacer and it immediately removed the interference. However with 1mm spacer I do not have enough room for a lock ring. I can screw the lock ring on but it is holding on too little thread (1 - 1.5 full turns only). I was naive and thought this will do but ruined a lock ring after a few rides. It was original aluminium lock ring from Sunrace.

Any ideas? Did anyone have similar issue with upgrading to 12 speed on standard hyperglide hub?

I see posts all over the interwebz about people successfully using MZ90 with Shimano HG hubs and so far I have not seen anyone reporting the same issue. I wonder, did I do something wrong?

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Update: Found a longer lock ring (from another Sunrace cassette) and assembled the whole thing in order: 1mm spacer, cassette, new lock ring. Managed to torque lock ring with no problem, there was enough thread. Will ride in that setup and see what comes out of it.

Big thanks go to @Nathan Knutson who's answer ended up being my solution and also to @Fred the Magic Wonder Dog for detailed explanation. I can only mark one answer as "accepted" ))

  • At a guess your wheel is a touch over dished/dished differently and the spokes are more parallel to the cassette plane than other wheels. The extra cogs are fit in by using the space beyond the limit of the hub. People who build wheels on this site might be able to tell you if you can correct that with a little re-truing. – Warren Burton May 3 '20 at 22:41
  • Dish was amongst my first guesses. I checked and the wheel is dished properly. Sits right in the centre of the space between chain stays / seat stays. I am considering changing the dish slightly to offset the wheel away from the cassette however it is not my preferred solution as I would be moving away from good/normal dish. Also interference occurs very close to the hub, therefore to achieve small change there I would need to accept a substantial offset at the rim, which I would prefer to avoid. – Art Gertner May 3 '20 at 23:19
  • Please remember comments are for clarifying or improving the question. We have a general purpose Bicycles Chat for those tangential discussions, or some points merit their own question. I'll pop these ones off into their own chat (which is not ideal but the best option available short of deleting it all. – Criggie May 5 '20 at 12:00
  • Comments are not for extended discussion; this conversation has been moved to chat. – Criggie May 5 '20 at 12:00
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Sounds like the easy solution is going to be get an extra long lockring. Wheels Mfg and another company I can't remember both used to offer them. I believe current Chris King ones are longer than average but I couldn't come up with a number.

Double check your wheel dish is right, because if it happened to be way over to the right, it could cause or contribute to this problem. But it would have to be extreme and you'd probably notice.

Another approach would be lacing tricks. I'm assuming it's 3x now. FH-M756 is the sort of hub where the shell has a fairly large smallest inscribed diameter and so torsional loads can be handled all by the left flange if you want, meaning you've got all sorts of options for half-rebuilding it, but not knowing where exactly the rub is I won't speculate what would be best in terms of being able to solve the problem while giving up the least bracing angle. The lower a cross number you choose, the further away from the hub the cross will be, and it's usually the cross area where you don't have the clearance you need in these situations. Just making it 2x or 1x on the drive side could very well solve the problem. There's also options that involve moving some or all of the drive side spokes to being heads-out, which also threatens to reduce the lateral strength of the wheel.

  • Ah, that's a lot of useful info. I will leave lacing tricks as a last resort. Not because I don't want to re-lace the wheel, but rather because this is my touring bike and I often load it up heavy. Going from 3x downwards will decrease durability and I am not the lightest of riders... I have never heard of extra long lock rings. Going to look for one now. – Art Gertner May 3 '20 at 23:33
  • Wheel dish checked. That would be easy to fix, but does not appear to be a root cause. On a side note: iterference is only observed when I spin the wheel of the bike on the repair stand. When the bike has some load (at least myself riding it) I have not yet heard cassette catching the spokes. – Art Gertner May 3 '20 at 23:42
  • @ArtGertner the risk there is you're running things so close that it won't take a lot for spokes to catch and then you're walking (assuming you still can walk after the sudden stop) – Criggie May 4 '20 at 0:00
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    @Criggie. I agree. And I would not take the bike in that state on anything more than a short test ride. That is why I am trying to resolve this. – Art Gertner May 4 '20 at 10:01
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There are unfortunately two HG standards. There is road HG and MTB HG. They were both the same for 9 speed, but diverged as the number of speeds went up. Basically MTB 11 spd cassettes with fit on a 9 spd hub of either standard. Road 11 spd require a slightly wider freehub ( you can put an MTB standard 11spd on a road 11spd hub with a thin spacer..)

It looks like you are trying to use a cassette for the wider road standard on an MTB hub. IMHO, you should either swap the hub or cassette.

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