Shift problems after installing Stronglight CT2 chainrings

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jsprbcn
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by jsprbcn

Hi all,

Yesterday I replaced my Rotor Q-rings (50/34 compact) with Stronglight CT2 chainrings (50/34 compact).
I am running Ultegra Di2 and with the Rotor Q-rings I had use of all gears exept for the 34/11 (I never got that one right but I wasn't using that one due to the cross chain line). I adjusted the front derailleur in order to shift with the round chain rings v.s. Q-rings so that should work.

With the Stronglight chainrings on the 34 chain ring when shifting up the cassette at gear 8-9-10 the chain is hitting the little iron plugs in the chainring (On the picture there are two of them).

Image

I tried all adjustments that I am aware of, but maybe I am overseeing anything?

The rotor crank is 10 speed, so the Q-factor should be good as it worked also before with the Q-rings....

Thanks inadvance.

jsprbcn
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by jsprbcn

When changing the cassette I found out that my Fulcrum Racing zero's have a 11sp hub with a spacer. I have 10sp Ultegra and the hub came with the wheels from a shop.
Can it be this hub combination? and that a normal 10sp hub wil solve the slightly to the right chain line which cause this rubbing?

https://www.youtube.com/watch?v=GFQhiRGEGyM

by Weenie


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dofman
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by dofman

I'm having a very similar issue with my strong light ct2 36-52,running a Fsa slk crankset with 11s ultegra di2.. Sent an email to strong light but no answer...

eric
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by eric

An 11sp hub + 1.8mm spacer will put the 10sp cassette in the same place as on a 10sp hub. I can swap between 11sp and 10sp hubs on my 10sp bike without adjusting the derailleur.

The small pins are there to help the chain shift.

There is no standard for the spacing between chainrings. Crank spider widths vary as do chainring width and the machining around the chainring bolts. You may need to add some thin spacers between one of the chainrings and the crank.

GT56
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by GT56

i know this does not resolve you specific problem but, why not put the ultegra crankset back on ?

compare the inside of the large chainrings, and you will find that shimano is becomes relatively slim (from relatively wide) towards the outside

this shape works as a guide for the chain preventing what you are describing (and on the road may lead to chain suck..)

jsprbcn
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by jsprbcn

My Ultegra cranks were sold over 1 year ago, so that's not an option.

Somone on another forum advised me to file off some of the "pins" in order to avoid the chain to be caught? can anyone confirm this?

mattr
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by mattr

They won't shift as well.

The catching is a combination of chain line, chain stay length, chain ring sizes (smaller rings with a larger difference will tend to do it more) and spacing between the rings.
The only thing you can really do is space out one ring by a fraction of a mm. Just so the chain clears the pins.
A thickness of coke can is probably enough.

mattr
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by mattr

FWIW the only bike I currently have with no catching in any gear (with the exception of small/small) is built up with a complete factory fresh 6800 group.

jsprbcn
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by jsprbcn

mattr wrote:They won't shift as well.

The only thing you can really do is space out one ring by a fraction of a mm. Just so the chain clears the pins.
A thickness of coke can is probably enough.


Okay, so by pushing the 34 chainring 1mm inwards with a spacer this should get some clearence in order to have at least untill gear 9 on the cassette without this issue (as mattr stages his small/small gear also did not work 100%)

mattr wrote:FWIW the only bike I currently have with no catching in any gear (with the exception of small/small) is built up with a complete factory fresh 6800 group.

Good to know. I don't remember if my Ultegra crank had this as well...

mattr
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by mattr

LOL.
1 mm is probably enough to run all your gears at the back from the little ring. And it'll probably cause shitting issues at the front.
If you needed an extra 1 mm clearance, you wouldn't have catching, the chain would be trying to actually start the shift.......
Start with coke can shims. That's about 0,1-0,15mm.
You may need 2 or 3 thickness, depending on how bad the issue is. But you can cut it with scissors.
Then you can (probably?) buy proper shims in the correct thickness.
As far as I know, it's only the very latest (last 1 or 2 generations?) of shimano kit that doesn't rub on a normal build (some frames have long enough stays not to rub with any set up, most don't)
I know almost all the builds/service I've done over the last ~20 years have had some rubbing in some combinations. Exceptions seem to be latest shimano road stuff, and campag 8 and 9 speed.
Though to be fair, I don't tend to use the gears that do rub, as they are almost all duplicates. So it's never caused me an issue (tho I have fixed it for friends who insist that every gear should work flawlessly!)

jsprbcn
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by jsprbcn

I have the same: 34T in the front and 11T-12T in the back is a cross chain line so I prefer to shift to the 50T.
It's just that I want to understand why, and try to fix it.

mattr
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by mattr

Be careful that fixing it doesn't cause bigger issues. Rattling chains in gears you don't use is less annoying than missed shifts or dropped chains

jsprbcn
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by jsprbcn

mattr wrote:Be careful that fixing it doesn't cause bigger issues. Rattling chains in gears you don't use is less annoying than missed shifts or dropped chains

True. Do you suggest to keep it how it is and not using those 2 gears or sent back the chainrings and stick to the Q-rings for a while longer?

audiophilitis
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by audiophilitis

jsprbcn wrote:
mattr wrote:Be careful that fixing it doesn't cause bigger issues. Rattling chains in gears you don't use is less annoying than missed shifts or dropped chains

True. Do you suggest to keep it how it is and not using those 2 gears or sent back the chainrings and stick to the Q-rings for a while longer?


Agree with mattr on this. Fixing the lift pin rubbing issue may compromise front shifting, or introduce new issues. I have the same issue on all of my bikes with Campy shifters/derailleurs and aftermarket cranks/chainrings. Since you shouldn't be riding on that gear combination anyway (small/small), I wouldn't mess around with filing down the pins or altering the distance between rings. Just my opinion.

mattr
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by mattr

It's your call really as to what you do.
My personal fix is to check which gears I can't use on a gear chart and to make sure I still have 2 or 3 over lapping/duplicated ratios on the gears I can use.
It might mean me needing either a different chain ring or cassette, but I usually base my buying decisions on what ive experienced in the past.
Hence the nice surprise on my 6800 group.

Prior to this there has usually been some sort of compromise. i.e. running a 36 inner ring as 34 is too small and rubs in gears I'd like to use, 36 moves me one or two sprockets over. But I need a 25 at the back instead of 23.......

FWIW. I've very very rarely found it a problem on 53/39 as the spread of gears works well. Even with rubbing.

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