Rear D touching spokes Tink tink tink tink

[redir]

Because this is only happening on one wheel of several that I have tried I think it rules out a bent RD hanger. The bike is a C'dale Synapse with a Powertap G-3 Hub and a 11-32 cassette.

The RD hanger is brand new, it's the kind that bolts on. By eye it looks straight and again this is the only wheel doing it. I've set the stop so that the chain barely gets on to the lowest cog. It only does it while under stress, so like a really steep hill. Once the hill levels out it goes away.

This led me to believe that dish or spoke tension had something to do with it so I gave each drive side spoke a half turn and trued it up. Still does it. My other PT G-3 wheel does not do it though that cassette is a 11-28 I think. I do not have a spoke tension meter but the other G3 wheel definitely has a higher pitch when plucking the spokes, audibly, and the spokes are actually longer on that wheel.

I cannot fit a spacer with the 11-speed cassette. Unless they make a thinner one then the one I have which is pretty thin.

When it's in the stand of course it doesn't do it but eyeballing it the RD looks to be at least 3-5mm away from any spokes so I'm not sure what is going on.

[Dude]

if you can't fit a spacer in there...
- make sure the low limit screw is set properly.
- you can't fit any spacer in there?
- ensure rear der is aligned with cassette properly - this is a function of the der itself might actually be bent and/or the brand new der hanger coulc still be bent and/or the dropout might be bent.
- ensure b screw is set properly

[oldguy00]

So in the work stand, when in the easiest gear, the cage is 3-5mm away from the spokes?
Are you sure the sound you hear when riding is the cage hitting the spokes? Is the cassette on tight, no play?

[CampyGrampy]

There may be interference between the cassette and the spokes. Powertaps have unusual hub geometry. I have had this issue with a G3. It was carrying the cassette when it should have been coasting. Turned out the issue was very occasional rub between the inner cog and where the spokes crossed. The fix was a changing to a cassette with a smaller inside cog. You might want to pull the cassette and check for any abrasions where the spokes cross nearest the flange.

[Alistair]

Swap cassettes - does the noise move with cassette?

Swap FH body - does the noise move with FH?

All else fails, time to N+1 your stable.

[November Dave]

11-32 cassette should have more clearance than an 11-28 cassette, so out of the gate this is funky.

If the wheel with the 11-28 cassette has a significantly deeper rim, that would increase the clearance as well as making it a stiffer wheel all else being equal.

As David Kirk suggests, different spoke patterns could affect this but with 3-5mm clearance by eye in the stand that should be plenty. PTap hubs drive from the ND side so this is one of the rare hubs that could be laced radially on the drive side - that's not what's happening with the wheel with the 11-28 cassette, is it?

I'd stop adding spoke tension without a good measurement. One wheel could be laced with thinner spokes than the other which would yield a different tone. If the 11-28 wheel has a deeper rim, the shorter spokes would make a higher tone. Etc.

If the wheel is moving around that much, you'd probably be seeing other funky things.

If it's a 10 speed cassette on an 11 speed freehub, you need that 1.85mm spacer between the cassette and hub, and the 11t is barely hanging on the freehub until the lock ring is tightened. If it's an Ultegra hub, they used another spacer behind but time is making memories of that hazy.

Assuming these are QR wheels, are you using different QRs with each? A crappy QR could let things move and cause weird things.

[CNY rider]

Originally Posted by November Dave

11-32 cassette should have more clearance than an 11-28 cassette, so out of the gate this is funky.
.

This is non-intuitive, at least for me.
Could you explain why?
Thanks.

[AngryScientist]

Originally Posted by CNY rider

This is non-intuitive, at least for me.
Could you explain why?
Thanks.

The further you get away from the centerline of the hub, tangentially, the further the spokes should be from the largest cog. Spokes angle in toward the rim, so a 32 cog, which has a larger diameter than a 28 should have the RD "lower" and closer to the rim than on a 28, which should decrease the chances of spoke contact.

man, what a ramble. does that make any sense?

[CNY rider]

Originally Posted by AngryScientist

The further you get away from the centerline of the hub, tangentially, the further the spokes should be from the largest cog. Spokes angle in toward the rim, so a 32 cog, which has a larger diameter than a 28 should have the RD "lower" and closer to the rim than on a 28, which should decrease the chances of spoke contact.

man, what a ramble. does that make any sense?

In fact it does, thank you.
I did not think about how the position of the RD changed with the larger cog.

[redir]

Looks like I have a lot of work to do tonight. Thanks for all the valuable info. I would have thought the opposite of a larger cassette too, intuitively. I think the 32 is the biggest one I have.

I forgot to mention it's the G3 laced to a Zipp 303. The other G3 hub I have is laced to an Open Pro.

Good suggestion looking for scratch marks. Yes it only does it under stress. I don't necessarily need to stand on the pedal but just sit and spin hard. I'll have to see on my morning commute tomorrow if it's the drive side pedal only.

[redir]

Is there a way to accurately measure a hangar to see if it's bent without special tools?

[Nomadmax]

Last time this happened to me it was the end of the RD cable hitting the spokes.

[tctyres]

Originally Posted by redir

Is there a way to accurately measure a hangar to see if
it's bent without special tools?

The easiest thing is an old wheel with a threaded axle. If you thread the axle into the derailleur hanger, the wheel is large enough that you will see a bend.

Originally Posted by Nomadmax

Last time this happened to me it was the end of the RD cable hitting the spokes.

+1 The last two generations of Shimano rear derailleurs send the cable right into the spokes, and it is not easily predictable in the stand.

EDIT: sorry you said a different wheel, not a different bike ...

[marciero]

To be clear, the two different wheels you tried have the same size large cog?
Also, regarding spoking that was mentioned- I would be curious if the they are the same- same number of spokes, and if so are drive side pulling spokes elbow in or out and do they cross under or over the first spoke. This wont fix your problems but might explain partly why one is fouling and one is not.

[Tandem Rider]

If the pulling spokes on the rear are "heads in" they will slightly move the crossing point towards the derailleur. This is only a problem when in the cog closest to the spokes and usually when climbing hard. Check the spoke tension if they are hand builts.