Occasional chain suck - new components

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fausto99
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Occasional chain suck - new components

Postby fausto99 » 5 Dec 2018, 1:06pm

As mentioned in another thread I'm getting very occasional chain suck using a low cost chainset from Spa. It is brand new, less than 500miles, with a new chain and it can be very reluctant to release the chain from the larger and middle rings. I have changed the inner from 28 to 24, so that I now have 48/38/24, but it's the change up and down to and from the 38 and the 48 which sometimes is less than smooth. I can't see what's going on as I ride, but it feels like chain "suck". It's always perfect on the work stand of course.

I'm still hoping it will settle in with use, but, having read some of Brucey's comments, I tried a different brand of chain. I originally had a KMC 8 speed. I now have an IG 6/7/8 (sic) speed chain. It has not made any noticeable difference. Spa cycles are mystified and have not had anyone else reporting this. Nowhere I have I read of people getting chain suck with new, clean components. Am I the only one?

Brucey
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Re: Occasional chain suck - new components

Postby Brucey » 5 Dec 2018, 1:29pm

check it to be sure but IIRC IG chains have a slightly larger internal width than other 7/8s chains so that is a useful experiment to do; one reason that chains don't shift well on the chainset is that they are tight on the teeth. They don't need to be tight tight to inhibit shifting BTW; they actually need a clearance on the tooth width before they will unship when pushed by a derailleur. One thing that can happen with new chainrings is that the teeth develop tiny burrs on the sides (from where the rollers bear against them) and these can be enough to degrade shifting before they are so big the chain actually gets stuck.

Some chainrings have pressed ramps in them, near the base of some teeth; occasionally these are large enough (by design or accident) that they can 'hold' a chain and it won't disengage; like chainsuck you can get the chain hitting the underside of the chainstay. You certainly can't use 9s chain on some (new) 8s chainrings because of this.

In this case I'm suspicious that the FD isn't doing quite the right thing for some reason (how is it set vs the chainrings?) and/or that the external width of the chain isn't a perfect match for the chainring spacing. However the latter would mainly influence the upshifts (onto bigger chainrings) rather than the downshifts (onto smaller chainrings).

It occurs to me that it may be possible with 9/10/11s chainrings (which have narrower teeth) for the chain to have so much clearance that it is less likely to unship than normal, but this is not something I have encountered before.

Spa chainsets can be had with various different chainrings; which ones do you have?

cheers
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RickH
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Re: Occasional chain suck - new components

Postby RickH » 5 Dec 2018, 1:46pm

I had bad chainsuck on a 26T steel inner on a triple (eventually found it was producing burrs where the teeth deformed slightly under pressure - even after filing them off they formed again so it wasn't a one off event).

It was much worse with a new chain (so much that I resorted to not using the inner ring for a couple of hundred miles with a new chain. I presume the lateral flexing widened the chain (pushed the outer plates apart slightly?) so it caught less.

My eventual cure was to replace the inner with an alloy TA one.

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Mick F
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Re: Occasional chain suck - new components

Postby Mick F » 5 Dec 2018, 1:52pm

The only issue I've ever had, is fitting a brand new Campag 10sp chain to the Moulton. 61/48/34 triple chainset.
The chain was reluctant to move off the 61t down to the middle, and also down to the inner. It had issues going back up, but not so bad.
Putting the older chain back on, and it was perfect.

As the chain "ran in" over the miles, all became sweetness and light.
I put it down to the new chain not having enough sideways flexibility that sorted itself out over time.

Maybe that's the issue with yours?
Mick F. Cornwall

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Chris Jeggo
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Re: Occasional chain suck - new components

Postby Chris Jeggo » 5 Dec 2018, 2:42pm

RickH wrote:I had bad chainsuck on a 26T steel inner on a triple (eventually found it was producing burrs where the teeth deformed slightly under pressure - even after filing them off they formed again so it wasn't a one off event).

I had this too. After I filed off the burrs for the second or third time the problem did not recur.

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fausto99
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Re: Occasional chain suck - new components

Postby fausto99 » 5 Dec 2018, 4:35pm

Brucey wrote:...Spa chainsets can be had with various different chainrings; which ones do you have?

In the OP is says I had a 48/38/28 which I changed to 48/38/24
I do worry about you sometimes Brucey :lol:

Brucey
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Re: Occasional chain suck - new components

Postby Brucey » 5 Dec 2018, 6:05pm

what I meant was that the Spa chainsets optionally come with the standard chainrings, stronglight chainrings, or TA chainrings depending on how you buy them. Obviously the standard chainrings vary with the exact model of chainset; we don't know that either.

Plenty of people change the chainrings at the time of chainset purchase; so much so that if you want cheap chainrings of the standard type, Spa can often oblige.

cheers
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531colin
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Re: Occasional chain suck - new components

Postby 531colin » 5 Dec 2018, 6:14pm

To me, "chainsuck" means the chain doesn't peel off the chainring at the bottom, but instead it gets carried up until it hits the front mech. cage.
By that specific definition, I have had chainsuck with a brand new chainring, where everything is new and sharp. I think its the freshly-machined edges and corners of the chainring teeth which bind on or in the new chain. I think I took off the new ring and blunted the corners of the teeth with the handle end of a small file. (The bit thats supposed to fit into a wooden handle). In any case, the chainsuck soon stopped.

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fausto99
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Re: Occasional chain suck - new components

Postby fausto99 » 5 Dec 2018, 10:06pm

Brucey wrote:what I meant was that the Spa chainsets optionally come with the standard chainrings, stronglight chainrings, or TA chainrings depending on how you buy them.

This one https://www.spacycles.co.uk/m2b0s109p20 ... e-Chainset with standard Spa chainwheels.

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fausto99
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Re: Occasional chain suck - new components

Postby fausto99 » 5 Dec 2018, 10:08pm

531colin wrote:To me, "chainsuck" means the chain doesn't peel off the chainring at the bottom, but instead it gets carried up until it hits the front mech. cage.
By that specific definition, I have had chainsuck with a brand new chainring, where everything is new and sharp. I think its the freshly-machined edges and corners of the chainring teeth which bind on or in the new chain. I think I took off the new ring and blunted the corners of the teeth with the handle end of a small file. (The bit that's supposed to fit into a wooden handle). In any case, the chainsuck soon stopped.

Thanks. Worth a closer look on a rainy day. I may well do some pre-emptive filing.

bgnukem
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Re: Occasional chain suck - new components

Postby bgnukem » 6 Dec 2018, 12:35pm

+1 for the burrs theory. Especially for softer / cheaper 'rings.

Fitted a cheap Stronglight steel granny ring to one of my several Spa triples and within a couple of hundred miles was getting chain-suck changing up. The ring is fairly thick (maybe designed for 7/8-speed chains) and formed burrs at the edges of the teeth really quickly which grabbed the chain. Deffo worth a check and deburr.

When you replace the 'rings try harder ones, e.g. Spa Cycle's own zicral rings...

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fausto99
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Re: Occasional chain suck - new components

Postby fausto99 » 8 Dec 2018, 10:01am

bgnukem wrote:+1 for the burrs theory. Especially for softer / cheaper 'rings.... Deffo worth a check and deburr....When you replace the 'rings try harder ones, e.g. Spa Cycle's own zicral rings...

Happy to report no chain suck last ride. However it was a solo ride, so no surprise changes of pace or gradient. Not a severe test.
I've had a look at the chainwheel teeth and can't see anything that might hang on to the chain but I am posting some pictures in case I'm missing something. On the front side of the large chainring there are a few little nicks in the teeth - to the right in this pic but there are some all round; about a dozen in all.

Image

On the backside and the middle ring I can't see anything unusual in this pic:

Image

As a matter of interest, how much harder is "zicral"? How much longer would they last?
Last edited by fausto99 on 8 Dec 2018, 11:06am, edited 1 time in total.

Brucey
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Re: Occasional chain suck - new components

Postby Brucey » 8 Dec 2018, 10:38am

is it my imagination or is the FD well above the big ring? If so, that won't help downshifts.

I also note that there is particle of aluminium on one of the teeth in your pictures, which suggest that 'something is happening' to the chainring teeth as they run-in.

Zicral chainrings wear quite a lot more slowly than cheaper chainrings do. However the thing that keeps chainrings good for longest is not running worn chains on them.

cheers
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fausto99
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Re: Occasional chain suck - new components

Postby fausto99 » 8 Dec 2018, 11:03am

Brucey wrote:is it my imagination or is the FD well above the big ring? If so, that won't help downshifts.
It just the angle I shot. The FD is positioned correctly 1-1.5 mm above the teeth of the big ring and parallel with same. Changes are super slick 99% of the time. It's not knowing when that 1% suck is going to happens that is cause for concern.

Brucey wrote:I also note that there is particle of aluminium on one of the teeth in your pictures, which suggest that 'something is happening' to the chainring teeth as they run-in.
Sorry I can't see it.

Brucey wrote: zicral chainrings wear quite a lot more slowly than cheaper chainrings do. However the thing that keeps chainrings good for longest is not running worn chains on them.
Couldn't agree more about worn chains.

PJ520
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Re: Occasional chain suck - new components

Postby PJ520 » 8 Dec 2018, 6:59pm

531colin wrote: (The bit thats supposed to fit into a wooden handle).
Is known as the tang.
You only live once, which is enough if you do it right. - Mae West