Slipping chains, exploding bassoons

by Martin Thomas   January 25, 2011  

Chainrings (photo: Martin Thomas)

I’m beginning to wonder if I made a rather expensive mistake last year.

In September I realised that my Campag Centaur chain, cassette and rings were wearing out so I treated myself to two TA Nerius 110 PCD chainrings (50 & 34) and a KMC 10-speed SL chain, together with a new Centaur cassette. 

Right from the outset I had shifting problems - specifically I kept losing my chain off the big ring when shifting up. Occasionally it would come off when shifting down too but that happened less often. I figured it must be an adjustment issue so I tweaked it as accurately as I could but still no joy - I'd lose the chain at least a dozen times every 50 mile ride. So I went to two separate LBSs and they tried to adjust it right but still the chain kept coming off. 

One mechanic said it's because they're not specifically designed to work together like my old all-Campag set-up and advised shifting more gently, but however gentle I am with it I still lose the chain at least four or five times a ride. This is particularly grating when I’m out on a club run and 20-odd cyclists are forced to wait while I fumble with my chain for the umpteenth time with oil-stained fingers. Not great for an outlay of nearly £200 (including the cassette).

Has anyone else had this problem? I've emailed the supplier, Dotbike, about it but I'm not really expecting them to do anything. 

Seems like I have to either live with it or shell out again - even though there's barely any wear on rings or chain. Or am I missing something obvious?

Seems to me it’s possible to learn some important lessons in life from cycling. Lessons like not messing with things when they’re not broken. Or that saving a handful of grams isn’t quite as important as things working properly in the first place. Or that, appealing though a change can be, it isn’t always as good as a rest. Or that wisdom after the event is sometimes about as much use as an exploding bassoon.

15 user comments

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aint that weird as just this weekend i had similar problems.
i swapped a 50T (SRAM rival) for a TA 48T chainring, although it is 9/10 speed it is a bit thicker than the SRAM ring, but the chain fits so no problem i thought. but the chain kept jumping off when shifting up (from the 34 to the 48) or not shifting at all when i adjusted the front mech. after an hour or so of messing with the front mech (try'd moving it up a few mm, down, left a bit then right etc) i swapped it for an old ultegra mech that i had knocking around. it worked first time, went out on sunday (157km) and not one slip or jump etc.

go figure eh!. Big Grin

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posted by Fringe [1081 posts]
25th January 2011 - 16:52

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And the lesson? Never throw anything away! If only I'd kept my old Campag rings...

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posted by Martin Thomas [567 posts]
25th January 2011 - 17:10

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I would take the set-up back to the LBS where you purchased them, reason with them that the set-up is not working. If they want you as a log term customer they should work with you............If you bought the items from an online retailer then, Blahahahahahahahahahahaha

posted by Fatrider [3 posts]
25th January 2011 - 19:48

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stiff link?

Binky

posted by davebinks [125 posts]
25th January 2011 - 20:18

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Totally frustrating to change something for the sake of spending money . Towards the end of a season you are better off relying on the old setup and tinkering with a new setup as the new season starts.
Found that the colder weather covers for a lot of bedding in problems. Past weeks in Austria the temperature has varied from -15c to +15c and the changeup & down has been difficult with a bit of slippage on the 11cog.
LBS people do their best but some problems elude the best of them.

Skippy(advocate for "Disabled / Para Sport")@skippydetour. blogging as skippi-cyclist.blogspot & Parrabuddy.blogspot currently on the road with ProTour Grand Tour Events .

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posted by skippy [383 posts]
25th January 2011 - 22:11

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Hiya, is the picture at the top of your article your bke? If so the problem is very obvious... the front Mech is in the wrong position on the seat tube far to high up... surely two lbs can't have both missed that? Si

posted by rootes [39 posts]
25th January 2011 - 22:20

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Cool Looks to me if the front mech is way too high-even for elliptical chainring. There can be other issues, of course, but I would start by lowering (and being sure to keep/obtain plate/ring alignment too) the mech until only 2mm between lower part of outer plate and teeth of the big ring exist. Modern systems can be so fickle. I love diversity of product, but after time and money wasting projects, have accepted to stick (or be stuck-as some would say) with same makers same tier products.

posted by Kim Chee [13 posts]
25th January 2011 - 23:52

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Perfecting the art of getting your chain back on with your shoe will keep your hands clean

If cycling is indeed a sport of self-abuse why aren't more cyclists sectioned under the mental health act?

posted by hairyairey [279 posts]
26th January 2011 - 0:30

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I agree that the changer looks too high up the seat tube. Also... if you stop pedaling as soon as you feel it derail, you can get the chain back on by reversing the change. It's not as easy with Ergo levers as it is with downtube levers, but it can be done fairly reliably.

Grizzerly

posted by Grizzerly [119 posts]
26th January 2011 - 8:08

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Thanks all. That front changer does look high doesn't it? Can't believe I've not spotted that before. I'll tinker with that and see how I get on. But it's been that height forever (AFAIK) and there were no problems with the all-Campag set-up so it's not *just* that. @Grizzerly, I've tried that finessing you talk about...sometimes works, usually doesn't, but that's probably just my hamfistedness.

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posted by Martin Thomas [567 posts]
26th January 2011 - 9:32

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Front derailleur set too high, yes, but also it looks like the cage on the mech is too wide for the chain. This could mean that when you change up, the inner cage plate pushes the chain out but the outer plate is not close enough to the chain to stop it coming off the ring. Same in reverse when changing down.

Also, is the front mech worn, especially the cage pivot? Play here could mean it's not holding the chain in place when completing a gear change.

I fancy that a new, tight, narrower, properly adjusted front mech would have a good chance of solving the problem.

Presumably your chain ring bolts are tight? No play in the bb? Can't see how any LBS would have missed any of this though!

posted by bikeylikey [163 posts]
26th January 2011 - 12:16

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had the same issue when i fitted KCNC rings to a 6600
Ultegra setup .... the spacing was wider than the
original Shimano setup by a couple of mm !!!!

still on the 3rd switch-back of Bwlch !

posted by therevokid [698 posts]
26th January 2011 - 13:12

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The spacing could be different with the TA rings whihc in trun will efefct the indexing - you could try spacing the rings out a little bit - I'm pretty sure someone (Problem solvers?) makes some washers specifically to do this.
It has to be done sometimes on singlespeed moutain bikes to get the chainline just right

posted by Duc [24 posts]
29th January 2011 - 22:06

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Well I moved the derailleur down a mil or two (the photo's deceptive actually...it wasn't very far out to start with) and that seems to have done the trick. NO chain loss on a 40-miler on Friday. Hurrah!

But now it kind of squeaks at me instead - once per chain revolution. So more investigations are called for [sigh].

The path of cycling efficiency rarely runs smoothly does it?

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posted by Martin Thomas [567 posts]
30th January 2011 - 11:55

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Congratulations! 2mm above the big ring works well.

Try two turns of PTFE tape on both pedal threads to see if the noise goes. Presumably it isn't the chain rubbng the front mech?

Also check the tightness of the chainring fixing bolts
, and that there is not play in your bottom bracket.

Nerd

Argon Welder

posted by Argon Welder [15 posts]
30th January 2011 - 23:18

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