rear derailleur rubbing spokes

[TheDrownedApe]

Recently bought a new wheel.

On the stand I've checked the position in the lowest gear and there is a decent gap between the derailleur and the spokes.

When i sit on the saddle on a hill i get the clang on the derailleur hitting the spokes, if i stand up it stops.

I'm a hefty lad (110kg); would tightening the spokes help?

[joshleb]

How do the spokes feel by hand? I can’t imagine there should be that much movement!

[Maximus_Meridius101]

Check that the mech hanger is straight, and not twisted, then get someone to look at how much the spokes ‘bow’ when you sit on the bike. It could be a single ( or couple ) of loose spoke(s) or that the hanger is twisted slightly.

[TheDrownedApe]

They feel "normal" (at least compared to the front spokes). Looking closer it seems the jockey pulley is the one that's probably rubbing as it's closer but the mech looks straight (tension pulley probably 1-2mm further away from the vertical)

Would a 1/4 turn of each spoke make that much of a difference (I'm new to this level of maint)?

[joshleb]

If the spokes feel ok, not being able to move them overly I doubt you are compressing the wheel to make them bow out.

As mentioned above, the mech hanger could be twisted slightly and when cycling under load this could pull the mech towards the wheel slightly.

What gearing set up does your bike have? Ie 3 front gears and 8 at the rear.

A solution could be to drop into the easiest front gear and then hopefully be able to not need to use the easiest rear gear to make it up.

[Mars]

Is it the upper or lower jockey wheel that's impacting the spokes? If it's the lower one, then the hangar or derailleur itself may be bent, either of which is an easy fix but you should get the hangar straightened first to be 100% sure. Not many people have a hangar straightener (I do - North Worcs if you're in the area) so maybe your local bike shop could be persuaded to check first for a tenner.

The upper jockey wheel shouldn't impact the spokes because it shouldn't move any further inward than it needs to push the chain onto the largest sprocket... unless there's something wrong with the dishing of the wheel itself. Possible and this would not be an easy fix - you're talking quite advanced level bike mechanics here. Even I would have to think hard about whether I wanted to get into that fix myself.

I would not try tensioning the spokes if you are unaware of the possible repercussions.

[TheDrownedApe]

As mentioned above, its the jockey pulley that is rubbing and the mech is straight

34-50 front and 11 speed 11-28 rear and yes I need the 28 around here (Infact new order bike has 11-32 in prep for JOGLE)

I've tried reindexing and managed about 1 turn further away so I guess I will see.

Thanks for the advice about not messing with the spokes (my limit is getting rid of buckles)

[Mars]

TheDrownedApe said:

As mentioned above, its the jockey pulley that is rubbing and the mech is straight

34-50 front and 11 speed 11-28 rear and yes I need the 28 around here (Infact new order bike has 11-32 in prep for JOGLE)

I've tried reindexing and managed about 1 turn further away so I guess I will see.

Thanks for the advice about not messing with the spokes (my limit is getting rid of buckles)

There are two pulleys in the derailleur, a guide (top one) and tension (bottom one). Which one is contacting your spokes?

And how do you know the hangar is straight? You can't eyeball this - the differences are small.

[TheDrownedApe]

Mars said:

There are two pulleys in the derailleur, a guide (top one) and tension (bottom one). Which one is contacting your spokes?

And how do you know the hangar is straight? You can't eyeball this - the differences are small.

Thanks for the reply

Weirdly I've been calling the two pulleys the jockey (top ) and tension (bottom) forever. Seems i mean the guide pulley then.

Its an educated guess as the issue only arose after changing the wheel. I guess if it is bent it will stay that way until i sell it.

[RC1807]

Look on YouTube how to check for and then realign a bent hangar. It's not *that*difficult, and it's certainly needed if your derailleur hits the spokes and stops the wheel turning.

[aka_kerrly]

RC1807 said:

Look on YouTube how to check for and then realign a bent hangar. It's not *that*difficult, and it's certainly needed if your derailleur hits the spokes and stops the wheel turning.

Many years ago me and a group of mates were out mountain biking. Firing down a twisty single track all following each other reasonably close and a mate caught his handle bar on a tree flipping him off the bike. The next guy ran over his bike and the guy behind him bailed over the bank.

The hanger on my mates bike was bent about 45* causing the derailleur to smash the spokes. In the middle of the woods several miles from home a small adjustable spanner and some man handling was required to straighten the hanger to an acceptable amount.

Comparing the old one with the new one , i agree with someone else's view that you cannot straighten them accurately enough by eye and if they are easily obtainable for your bike it could be worth getting a new one if after playing around with the spokes/the derailleur.

Another thought, is there any play in your hub bearings ?

[johnpsanderson]

aka_kerrly said:

if they are easily obtainable for your bike it could be worth getting a new one

I’d never try and bend a sacrificial hanger back straight, apart from as an emergency fix to try and get home, it’d expect a fair chance it’d snap in the future. If it’s bent, definitely replace!

[jfdi]

Are you on a 9 or 10 speed cassette? If so have you put the spacer on the hub first?

[Maximus_Meridius101]

jfdi said:

Are you on a 9 or 10 speed cassette? If so have you put the spacer on the hub first?

Or get another small shim spacer, and move everything out a bit, if there’s space on the freehub.

[David_M]

jfdi said:

Are you on a 9 or 10 speed cassette? If so have you put the spacer on the hub first?

+1 - this was what I was scrolling down to suggest - 1mm spacer goes on first for 10-speed cassette.

[Mars]

johnpsanderson said:

aka_kerrly said:

if they are easily obtainable for your bike it could be worth getting a new one

I’d never try and bend a sacrificial hanger back straight, apart from as an emergency fix to try and get home, it’d expect a fair chance it’d snap in the future. If it’s bent, definitely replace!

Depends how bent it is. They are very tolerant of minor corrections. In fact, even fitting a brand new one should involve you tweaking it with a straightener.

[Mars]

TheDrownedApe said:

Thanks for the reply

Weirdly I've been calling the two pulleys the jockey (top ) and tension (bottom) forever. Seems i mean the guide pulley then.

Its an educated guess as the issue only arose after changing the wheel. I guess if it is bent it will stay that way until i sell it.

If your gears index OK, your derailleur is likely to be straight... but worth giving it a look-over once in a while. I'd say 75% of the bikes I get in to check-over need their hangar straightened. Gear adjustment is so much easier once this is addressed.

However, in this case, as other people have noted, it does sound like you're missing the spacer. This should be the comprehensive write-up for this:

https://www.slowtwitch.com/Tech/Cassette_Spacers_2...