chainset noise

[le.voyageur]

I wnoder if folks can offer some advice please.

I have a 9 speed double setup and when in the small at the front and from about the 3rd smallest) to the smallest at the back my chain hits the ramps on the outer chain ring.

I know small/small is not advisable but I should be still able to use it without it hitting the ramps shouldn't I?

In case it helps, it's 135mm oln rear hub and the cranks are HT2 cranks so I can't fiddle too much with the chainline.
I could put a spacer between the DS cup and the BB shell?

Any advice welcome.
Thanks.

[mercalia]

apparantly not

[Eyebrox]

Reset the derailleur. Follow the steps on the Park Tools guide. Remember the cage will have extra fine-tuning facility via the trim function. Could even be a worn BB.

[Samuel D]

I know small/small is not advisable but I should be still able to use it without it hitting the ramps shouldn't I?

Not necessarily. Depending on a few things (chain stay length, chain width, chainring spacing, etc.), it’s often the case that the chain will hit those ramps. Most road bikes I’ve ridden have suffered some form of chainring rubbing in small-small.

This isn’t ever a sensible gear to use anyway (unlike big-big, which is sometimes useful for a brief period).

I wouldn’t try to ‘fix’ this. Fixing it by changing the chainline will worsen the more serious problem with typical double set-ups: that the chain often runs at a bad angle on the large chainring and the commonly used inner half of the cassette.

[gregoryoftours]

It's normal on a road double chainset for the chain to catch the lifting pins on the inside of the big ring when in small/small, and maybe just a slight tickle occasionally when in second smallest rear sprocket, but third one in is pushing it a bit. Maybe your frame has a mtb chainline but has been built up with a road double chainset and associated chainline so there is a mismatch between front and rear? If you measure this and it turns out to be the case you could try spacing the driveside cup of the bb a bit. You might have to sort out front shifting if you did this, possibly with use of an eccentric front mech shim and 34.9 band on mech if your seat tube is not already 34.9mm diameter. If your front mech is a mountain model the mech will need adjusting but should work fine with the wider chainline at the front. Just a thought, it would also be worth checking that your smaller front ring is not mounted the wrong way around, it's probably not as there would likely be other more serious problems if so, like the chain throwing off when changing, but another symptom would be the chain catching on the big ring pins in more gears than usual due to the narrower than normal chainring spacing.

[le.voyageur]

Thanks guys for the input, I'll do some measuring and see if anything jumps out but it's sounding like hitting the ramps in 2nd and smallest cog is expected.
I think the group all matches, it's a compact road double on audax bike.
I'll check the chainring are mounted corerctly.
thanks

[iandusud]

I would suggest that a slightly longer BB is called for.

[reohn2]

Thanks guys for the input, I'll do some measuring and see if anything jumps out but it's sounding like hitting the ramps in 2nd and smallest cog is expected.
I think the group all matches, it's a compact road double on audax bike.
I'll check the chainring are mounted corerctly.
thanks

If it's compact road double ie; 34/48,50,52 then larger the difference between inner and outer rings also increases the likelihood of the chain scraping the front mech in small/small gears,whereas a larger inner ring such as the old 42/52 lessened the chance.
The way around this is a friction front changer but as Samuel has posted small small gear use causes cross chaining so isn't ideal.

[Samuel D]

If it's compact road double ie; 34/48,50,52 then larger the difference between inner and outer rings also increases the likelihood of the chain scraping the front mech in small/small gears,whereas a larger inner ring such as the old 42/52 lessened the chance.

Not only does a large chainring difference increase the risk of the chain rubbing the derailleur (solvable with a friction shifter as reohn2 mentions), it also increases the risk of the chain rubbing the inside of the large chainring. So that’s another contributing factor when present.

[reohn2]

If it's compact road double ie; 34/48,50,52 then larger the difference between inner and outer rings also increases the likelihood of the chain scraping the front mech in small/small gears,whereas a larger inner ring such as the old 42/52 lessened the chance.

Not only does a large chainring difference increase the risk of the chain rubbing the derailleur (solvable with a friction shifter as reohn2 mentions), it also increases the risk of the chain rubbing the inside of the large chainring. So that’s another contributing factor when present.

That's what I trying to say

[gxaustin]

I note that you have a 135mm rear spacing which will put the smallest rear cog a little bit more outboard and hence make rubbing more likely. On the other hand I know plenty of people with disc braked road bikes and compact chainsets (34/50) who run that setup without problems. What sized chainrings are you using? Do you have the correct chain? It sounds like a daft question but I did mismatch mine once and it worked mostly - but not quite.
Have you checked the chainline by measuring the distance from the centre of the down tube to the big cog? That's 46mm to the centre of the big ring and 5mm less for the small ring, from memory. It should be OK considering its HT2 but just a thought.

[le.voyageur]

thanks again for all the input.
It looks like the inner is mounted incorrectly as all the writing is facing inwards.
I'll flip it over and see if it resolves.

I dont understand the comments about the bar end shifter as once I've shifted (and trimmed if required) the chain isn't touching the FD, how would a different shifter help?

[Samuel D]

I dont understand the comments about the bar end shifter as once I've shifted (and trimmed if required) the chain isn't touching the FD, how would a different shifter help?

It wouldn’t if your existing trim function adequately solves the problem. Sometimes it does not, again depending on a host of factors.

Why do you wish to use small-small gears? They are less efficient at power transfer, incur greater chain and sprocket wear, suffer from chordal action (vibration), make more noise, and prevent quick up-shifting if unexpectedly needed.

[Brucey]

if it is HT-II then it seems likely that the chainset is really a 10s one? If so, fitting the slightly wider 9s chain will cause this exact problem.
I would suggest that you can fit thin spacers between one of the chainrings and the spider and resolve the problem this way. If you overdo it the chain may skid on the tops of the small chainring teeth when you downshift; you will soon know if this is happening or not.

Very often if you swap chainring manufacturers on a 10s or 11s compact double, you end up in the same pickle. I have even known folk grind off the pins to stop the noise. This works, but does nothing for the shift quality, obviously.

You can buy spacers down to 0.6mm

https://www.sjscycles.co.uk/chainsets/06-alloy-chainring-spacers-pack-of-5/

cheers

[foxyrider]

thanks again for all the input.
It looks like the inner is mounted incorrectly as all the writing is facing inwards.
I'll flip it over and see if it resolves.

When you say facing inwards do you mean in towards the frame or into the chainset? It actually takes some effort on most chainring to mount them wrong as the bolt heads sit into a recess around the hole. If you mount the wrong way the bolts will usually come up short or only just catch.

I find any chain noise from s/s to be a useful aid in telling me I need to change chainring. The short wheelbase on my race bake exacerbates the issue for me so whilst I can get all 22 gears in the small ring I get rubbing in the smallest four sprockets. (this is running 52/34 with 11-27 cassette which runs straight through from 11 to 16 before bigger jumps up to the 27)