just fitted new components to my bike, cassette, rear mech, front mech, new bb and chain set, working smoothly but when the 8th and 9th cog and on the front small chain ring the chain rubs on the outer large chain ring, almost to the point where it moves from small to large without using the front mech, totally lost, all components shimano tiagra, any ideas.?
chain alignment
- Thread starter cerenko
- Start date
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Steve Malkin
Veteran
- Location
- Cheshire
I'm no expert, and I dare say others on here will be able to advise you better, but from the symptoms you describe it does sound as though your chainline is out of alignment.
You would get these symptoms if the front chain rings were too close to the frame, making the angle of the chain more extreme when running in the small front / small rear combinations.
Since you say you've changed the bottom bracket and chain set then that sounds like the most likely explanation to me.
Did you replace the bottom bracket with one of the same axle length as the previous one? a shorter axle would cause the chain rings to be closer to the frame.
In terms of sorting it out, I think the options are a BB with a longer axle length, or spacer washers between your new BB and the BB shell to make the chain rings sit further out from the frame. There may be something you can do at the rear end to correct it by bringing the cluster further inboard instead, but I don't know how you would do that, others on here may be able to advise.
Of course running in these 'extreme' gear combinations is not really recommended anyway because the bend they induce in the chain is likely to lead to high wear rate but it should be possible to get them to work without any significant rubbing if the chain line is optimal.
Best of luck in getting it sorted!
You would get these symptoms if the front chain rings were too close to the frame, making the angle of the chain more extreme when running in the small front / small rear combinations.
Since you say you've changed the bottom bracket and chain set then that sounds like the most likely explanation to me.
Did you replace the bottom bracket with one of the same axle length as the previous one? a shorter axle would cause the chain rings to be closer to the frame.
In terms of sorting it out, I think the options are a BB with a longer axle length, or spacer washers between your new BB and the BB shell to make the chain rings sit further out from the frame. There may be something you can do at the rear end to correct it by bringing the cluster further inboard instead, but I don't know how you would do that, others on here may be able to advise.
Of course running in these 'extreme' gear combinations is not really recommended anyway because the bend they induce in the chain is likely to lead to high wear rate but it should be possible to get them to work without any significant rubbing if the chain line is optimal.
Best of luck in getting it sorted!
baldycyclist
Über Member
- Location
- Sunderland
I would not be running on smaller front and smallest rear - the rear pulls the chain to the right and yes it will rub and or change
advice is usually to not go to the highest gears whilst on the small front. middle front can use majority of rear, bigger front tends to mean that you need to stay in the higher range in the rear.
If you occasionally need to mix it up then fine but not fo rlong periods or the chain, cassette and chain set wears badly.
I think you know all this though
!?
advice is usually to not go to the highest gears whilst on the small front. middle front can use majority of rear, bigger front tends to mean that you need to stay in the higher range in the rear.
If you occasionally need to mix it up then fine but not fo rlong periods or the chain, cassette and chain set wears badly.
I think you know all this though
!?
Thanks for the reply, i am now sure that it needs a spacer on the drive side, only about 3 mm, when i say
rubbing I mean really rubbing, only problem is I can only find a spacer on a American web site, unless anyone knows of somewhere else. its a holloewtech 2.
Thanks
rubbing I mean really rubbing, only problem is I can only find a spacer on a American web site, unless anyone knows of somewhere else. its a holloewtech 2.
Thanks
Steve Malkin
Veteran
- Location
- Cheshire
steve52
I'm back! Yippeee
- Location
- bottesford scunthorpe
may be a small matter of adjusting the limit screws, but as others have said you really shouldent be useing smallest frount and smallest rear, keep the chain as st8 as possible for the gear range you need its more efficent, next time you go shopping carry the bag keeping a bend in ur elbow see how much easyer it is to keep it st8,
fossyant
Ride It Like You Stole It!
- Location
- South Manchester
You aren't supposed to use those sprockets on the small front ring. The pins and ramps on the larger ring will indeed try to pull it up. I wouldn't go fitting spacers to the bb on a hollowtech - for one you aren't supposed to and it will then end up off setting the drive side - could cause hip and knee issues.
ok, job done by me not the shop, fitted a 2.5mm spacer to drive side, i now have use of the 7th 8th and 9th cog, i know i should not use small small but at least its there should i need it, should have at least been able to use 7 and 8 with out it rubbing on large chain wheel badly. I also took the new KMC chain off and put the old one back on, shimano and it worked like a dream so went out and paid more money on a new shimano chain and everything is now running smothly, seems the KMC chain was not compatable with my set up ?
