Chain slipping Between Chainrings

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531colin
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Re: Chain slipping Between Chainrings

Post by 531colin »

slowster wrote: 25 Jun 2022, 8:19am I wonder if raising the derailleur by 2mm-4mm might be enough to make the shifts work cleanly. Indexing works by always moving the the derailleur cage on its pivot by the same angle. Placing the pivot point of the cage a bit further away from the chain may increase the distance which the cage moves the chain when downshifting by just enough to stop the chain falling between the chainrings.

Edit - Ignore this as it is garbage. There are two pivots and the cage moves horizontally through the same distance for any given amount of cable pull..
Are you sure its garbage? Your memory for this stuff is usually better than mine, and your ability to dig out stuff from old threads is unsurpassed, but.......
I think I remember Brucey writing that correct chainline was important not only so the mech. could reach both ends, but also the "throw" of the mech. wasn't strictly linear with cable pull, so that you had to get the rings in the right place for the mech. to deliver the right amount of throw for each change.

I also seem to remember something about the STI pulling differing amounts of cable depending on which shift it was, but that might be for the rear.

Having re-read it all, I'm not certain we are talking about the same stuff......... :(
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Mick F
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Re: Chain slipping Between Chainrings

Post by Mick F »

My issues were with friction DT shifters.
The chain would often slip between the outer and middle, and the cranks had no purchase, just a grinding noise.

The Moulton originally came with a Connex (like I mentioned) as well as STIs.
I hated the STIs so fitted friction.

All was perfect and well until I fitted a Campag chain.

No matter how I shifted, the chain would often drop between the rings. What I got into the habit of, was to shift outer to inner, then back up to middle. It drove me mad until I bit the bullet and took out all the spacers I ground them down.

Trial and error got them perfect.
No between rings issues at all now, and I don't expect them either.

How Stronglight can produce a 9sp/10sp compatible triple, I don't know. Chain widths vary even on 9sp and on 10sp too ........... as I found out with 10sp. No doubt it works perfectly with all 9sp chains without modification, but 10sp is does not.
Mick F. Cornwall
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CyberKnight
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Re: Chain slipping Between Chainrings

Post by CyberKnight »

late to the party but my tuppence with regards the 1st post
ride mate had the same issue and it turns out the inner chainring was fitted with the inner side facing outwards
John Wayne: "I won't be wronged, I won't be insulted, and I won't be laid a hand on... I don't do these things to other people, and I require the same from them."
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531colin
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Re: Chain slipping Between Chainrings

Post by 531colin »

CyberKnight wrote: 25 Jun 2022, 7:37pm late to the party but my tuppence with regards the 1st post
ride mate had the same issue and it turns out the inner chainring was fitted with the inner side facing outwards
That should be obvious if you look at the middle chainring and compare the gap to the big ring and the small ring. Chainring teeth are usually offset a bit from centre....if the teeth are offset 2mm, that makes a 4mm difference between the two gaps either side of the middle ring, if the middle ring is the wrong way round.
iandusud
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Re: Chain slipping Between Chainrings

Post by iandusud »

CyberKnight wrote: 25 Jun 2022, 7:37pm late to the party but my tuppence with regards the 1st post
ride mate had the same issue and it turns out the inner chainring was fitted with the inner side facing outwards
Thanks for chipping in. However the rings are fitted correctly.

I haven't had the opportunity to try it since I last adjusted everything but if I continue to get the same issue I think I'll carefully file down the outside of the spider lugs to bring the outer ring in slightly. Reading all of the above makes me think that Shimano have designed their triple STI front gears to work with absolutely an optimal setup, using only their own chainset, meaning that any other setup leaves little or no margin for deviation.
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531colin
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Re: Chain slipping Between Chainrings

Post by 531colin »

iandusud wrote: 26 Jun 2022, 6:57am ............. I think I'll carefully file down the outside of the spider lugs to bring the outer ring in slightly. ..........
If you get it wrong, its a less expensive mistake if you file the chainring rather than the spider.
You aren't going to try a 9 speed chain, are you?
iandusud
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Re: Chain slipping Between Chainrings

Post by iandusud »

531colin wrote: 26 Jun 2022, 9:03am
iandusud wrote: 26 Jun 2022, 6:57am ............. I think I'll carefully file down the outside of the spider lugs to bring the outer ring in slightly. ..........
If you get it wrong, its a less expensive mistake if you file the chainring rather than the spider.
You aren't going to try a 9 speed chain, are you?
I take your point re filing the spider but I think I'll find it easier to file the spider accurately and if I change my mind I can always pop along to Spa and buy some of their shims! :)
I'm assuming that a 9 speed chain won't work with a 10 speed cassette?
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531colin
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Re: Chain slipping Between Chainrings

Post by 531colin »

iandusud wrote: 26 Jun 2022, 9:14am .............
I'm assuming that a 9 speed chain won't work with a 10 speed cassette?
I don't think you will know unless you try it on your machine.
An 8 speed chain works on my 9 speed bike.....
a page or so back......
531colin wrote: 24 Jun 2022, 12:06pm
Mick F wrote: 23 Jun 2022, 7:55pm
iandusud wrote: 23 Jun 2022, 3:59pm ..................
I assume that a wider chain (9 speed) wouldn't work with a 10 speed cassette.
Of course not.
My issue was swapping a 10sp Connex chain for a 10sp Campag one.
Indexing was, and still is perfect but the Campag chain, being narrower, would often sit between the outer and middle rings, and the cranks would spin................
If nominally 10 speed chains from different manufacturers are different widths, what is the basis for the assertion that a 9 speed chain won't work on a 10 speed setup?

I have a couple of 8 speed bikes and only one 9 speed. The 9 speed bike works perfectly fine with an 8 speed chain, and always has done, because when I built it up I thought it would be easier for spares if they all ran the same "8 speed" chain. (which has been whatever was around at Spa at the time....originally Connex I think, recently KMC
Mine are all friction front shift, I guess its possible that an indexed front shift (and trim) wouldn't cope with a wider chain, but I wouldn't write it off without trying it.

What is the (nominal) difference in chain widths, does anybody know where we might find the information?
Some information here......https://en.wikipedia.org/wiki/Bicycle_chain
roubaixtuesday
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Re: Chain slipping Between Chainrings

Post by roubaixtuesday »

iandusud wrote: 26 Jun 2022, 6:57am
CyberKnight wrote: 25 Jun 2022, 7:37pm late to the party but my tuppence with regards the 1st post
ride mate had the same issue and it turns out the inner chainring was fitted with the inner side facing outwards
Thanks for chipping in. However the rings are fitted correctly.

I haven't had the opportunity to try it since I last adjusted everything but if I continue to get the same issue I think I'll carefully file down the outside of the spider lugs to bring the outer ring in slightly. Reading all of the above makes me think that Shimano have designed their triple STI front gears to work with absolutely an optimal setup, using only their own chainset, meaning that any other setup leaves little or no margin for deviation.
I've no experience with Tiagra, but 9 speed Sora triple on our tandem with stronglight chainrings works impeccably.
iandusud
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Re: Chain slipping Between Chainrings

Post by iandusud »

roubaixtuesday wrote: 26 Jun 2022, 9:33am
iandusud wrote: 26 Jun 2022, 6:57am
CyberKnight wrote: 25 Jun 2022, 7:37pm late to the party but my tuppence with regards the 1st post
ride mate had the same issue and it turns out the inner chainring was fitted with the inner side facing outwards
Thanks for chipping in. However the rings are fitted correctly.

I haven't had the opportunity to try it since I last adjusted everything but if I continue to get the same issue I think I'll carefully file down the outside of the spider lugs to bring the outer ring in slightly. Reading all of the above makes me think that Shimano have designed their triple STI front gears to work with absolutely an optimal setup, using only their own chainset, meaning that any other setup leaves little or no margin for deviation.
I've no experience with Tiagra, but 9 speed Sora triple on our tandem with stronglight chainrings works impeccably.
What front mech and lever are you using?
roubaixtuesday
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Re: Chain slipping Between Chainrings

Post by roubaixtuesday »

iandusud wrote: 26 Jun 2022, 2:24pm
roubaixtuesday wrote: 26 Jun 2022, 9:33am
iandusud wrote: 26 Jun 2022, 6:57am
Thanks for chipping in. However the rings are fitted correctly.

I haven't had the opportunity to try it since I last adjusted everything but if I continue to get the same issue I think I'll carefully file down the outside of the spider lugs to bring the outer ring in slightly. Reading all of the above makes me think that Shimano have designed their triple STI front gears to work with absolutely an optimal setup, using only their own chainset, meaning that any other setup leaves little or no margin for deviation.
I've no experience with Tiagra, but 9 speed Sora triple on our tandem with stronglight chainrings works impeccably.
What front mech and lever are you using?
It's 9 speed current Sora.

I think R3030 is the model number
20220626_143729.jpg
zenitb
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Re: Chain slipping Between Chainrings

Post by zenitb »

iandusud wrote: 26 Jun 2022, 9:14am
531colin wrote: 26 Jun 2022, 9:03am
iandusud wrote: 26 Jun 2022, 6:57am ............. I think I'll carefully file down the outside of the spider lugs to bring the outer ring in slightly. ..........
If you get it wrong, its a less expensive mistake if you file the chainring rather than the spider.
You aren't going to try a 9 speed chain, are you?
I take your point re filing the spider but I think I'll find it easier to file the spider accurately and if I change my mind I can always pop along to Spa and buy some of their shims! :)
I'm assuming that a 9 speed chain won't work with a 10 speed cassette?
Ian I had this same "chain riding" problem yesterday (on a Tandem Club group ride) so I still have the issue ..and my stoker is pushing me to get it fixed ASAP. My rear cranks are (now sold out) 160mm Thorn ones which although very effective are not well finished on the inside. I am going to take the rings off and look at the crank faces ..with a view to also filing them down. Please let us know how you get on with your fix...
Cheers :-)
peetee
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Re: Chain slipping Between Chainrings

Post by peetee »

These cranks are supposed to be compatible with ten speed. My question to the supplier would be’which ten speed?’
The original derivative of ten speed introduced in the 2000’s had mechs of much the same, if not identical, geometry as 7, 8 & 9 speed mechs so the spring rates, lever action and cage movements were all much the same. ‘New’ ten speed follows the 11 speed rules where the shift is much more snappy, much quicker when set up correctly and, it has to be said, from a set up perspective much more finicky.
I could see how a common fit, all-things-to-all cyclists crankset would indeed suit old ten speed but wouldn’t have the more exacting compatibility/precision that is needed to work with current groupset standards
The older I get the more I’m inclined to act my shoe size, not my age.
iandusud
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Re: Chain slipping Between Chainrings

Post by iandusud »

peetee wrote: 27 Jun 2022, 2:04pm These cranks are supposed to be compatible with ten speed. My question to the supplier would be’which ten speed?’
The original derivative of ten speed introduced in the 2000’s had mechs of much the same, if not identical, geometry as 7, 8 & 9 speed mechs so the spring rates, lever action and cage movements were all much the same. ‘New’ ten speed follows the 11 speed rules where the shift is much more snappy, much quicker when set up correctly and, it has to be said, from a set up perspective much more finicky.
I could see how a common fit, all-things-to-all cyclists crankset would indeed suit old ten speed but wouldn’t have the more exacting compatibility/precision that is needed to work with current groupset standards
Without stripping the rings off a Shimano triple road crankset and the same with the Spa one, and then doing some careful measuring it's hard to say, but I suspect that you are correct. Our second "beater" tandem is going to get a set of bar-end shifters later this week. None of these problems with those.
slowster
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Re: Chain slipping Between Chainrings

Post by slowster »

I think the following might be a factor. From another thread:
iandusud wrote: 26 Dec 2021, 9:50am We are currently having a tandem frameset built. I have specified 26" wheels.
The Tiagra front derailleur is a road front mech. It has been designed to work on bikes with a seat tube to chainstay angle of 63 to 66 degrees. On a 26" wheeled bike that angle will typically be larger. Consequently the angle of the chain run relative to the derailleur cage will be altered.

I think that during the downshift the channel in the outer cage is designed to pick up and hold the chain until the cage has moved far enough inboard to ensure that when the chain drops out of the channel it falls cleanly onto the middle ring. I suspect that too large a seat tube/chainstay angle results in the chain not being properly picked up and held by that channel, with the result that the chain drops down to the middle ring before the cage has moved far enough inboard to ensure that the chain will fall cleanly onto the chainring's teeth.

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