Chain slipping Between Chainrings

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iandusud
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Chain slipping Between Chainrings

Post by iandusud »

I've just fitted a new chainset on our tandem, a Spa TD2 triple. I'm having problems when changing from the large chainring (46t) to the middle (36t) where the chain doesn't engage with middle chainring but just slips against the inside of the outer ring. It is as if there is too much spacing between the chainrings. I'm running it with a Tiagra 4703 10 speed set up Spa claim that this chainset is suitable for 10 speed. Anyone come across this problem?
TheBomber
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Re: Chain slipping Between Chainrings

Post by TheBomber »

It’s a problem I’ve had when using very old chainsets with a modern chain. But generally even then only when down shifting at the front whilst still in a small sprocket at the rear (which is a very strange thing to do). Do you get the problem when in any sprocket at the rear? Increasing the chainline may help?
iandusud
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Re: Chain slipping Between Chainrings

Post by iandusud »

TheBomber wrote: 22 Jun 2022, 8:41pm It’s a problem I’ve had when using very old chainsets with a modern chain. But generally even then only when down shifting at the front whilst still in a small sprocket at the rear (which is a very strange thing to do). Do you get the problem when in any sprocket at the rear? Increasing the chainline may help?
It happens across the cassette.
slowster
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Re: Chain slipping Between Chainrings

Post by slowster »

Spa sell TD-2 chainsets with various different chainrings - TA, Vision (their own premium chainrings manufactured like TA's), and Spa's own brand zicral rings. The website states that all are 10 speed compatible (whereas the XD-2 with Stronglight rings is only rated for up to 9 speed), but it might help if you confirm which type you have, and also which brand/model of chain you have fitted.

It might also be worth checking the thickness of the washers fitted between the middle ring and crank - they should be 0.45mm according to this thread - viewtopic.php?t=145349.

I would have expected that Spa themselves do 10 speed builds using the TD-2 chainset and that derailleur, so I would email or telephone them to see if they can advise.
iandusud
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Re: Chain slipping Between Chainrings

Post by iandusud »

Chainring supplied with Spa zicral chainrings. I'm running a Shimano 10 speed chain. No washers between the middle ring and crank, in fact no washers at all.
peetee
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Re: Chain slipping Between Chainrings

Post by peetee »

Try backing out the bottom limit screw on the front mech a half turn. I don’t have a lot of experience setting up the 4700 series shifters but this seems to work for some others. I think what might be happening is that when changing down from the big ring the range of movement left for the mech is too short to give the chain a hard enough shove to provide a clean shift. In theory this doesn’t hold water as the shifter dictates the amount of slack but, as I say, it does seem to work with some other Shimano shifters.
The older I get the more I’m inclined to act my shoe size, not my age.
slowster
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Re: Chain slipping Between Chainrings

Post by slowster »

In the light of peetee's comments, presumably any excessive friction etc. in the gear cable could have a similar effect in reducing the force of the spring, and the extra length of the gear cable on a tandem might exacerbate that.

Maybe review which model of cable inner and outer you have, since there seems to be a range of different qualities of gear cable all at very different prices, although I don't understand all the differences myself (SP41?, 'Optislick'?, polished stainless etc. etc.). In the meantime I would double check the existing cabling for any irregularities, e.g. pull off the ferrules and check that the ends of the outers are cleanly cut etc.
peetee
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Re: Chain slipping Between Chainrings

Post by peetee »

I think slowsters comment is more pertinent than mine. I must admit that I missed that we were discussing a tandem and as such the set up of the front cable is the most likely culprit as the ‘new’ 10 speed, along with the 11, requires extremely precise and high quality cable set-up.
The older I get the more I’m inclined to act my shoe size, not my age.
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531colin
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Re: Chain slipping Between Chainrings

Post by 531colin »

Indexed tandem front shifting will flush all the gremlins out of the woodwork!
Sorry for the "teaching granny to suck eggs" element, but I assume you have checked
chainline?
Can you lower the mech. at all? I think it will be based on 11T difference big to middle (50/39/30?) ...I wouldn't expect 10T difference to be a big issue, but you never know?
Can you align the mech. so that the outer cage plate is slightly "toed-in" towards the front of the bike? (or....whisper it..."form" the outer cage plate a touch to get the same result)
As already said, look for draggy cables .....and maybe shifter function/trim positions, although thats outside my experience.

Re the washers on these Sugino cranks....I'm well out of date with all this stuff, but washers can't be missing, because if they were the big and middle rings would be too close together. (and if they are missing from a chainset where they are needed, it looks comic, because the gaps between the rings are obviously different....middle and big ring too close, granny ring in the next county)

Phone Spa its random who answers the phone, so make it clear you don't need an answer right now you want somebody to ring back with a considered answer.
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Mick F
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Re: Chain slipping Between Chainrings

Post by Mick F »

I have a Stronglight Z-Lite triple on my 10sp Moulton.
http://www.stronglight.com/stronglight/ ... uit?id=276
When the bike was new, it had a Connex chain on it.
I eventually replaced if with Campag, but the Campag chains are a tiny bit narrower, so it was often sitting between the outer and middle rings. On my 2nd or 3rd Campag chain on it. Excellent chains! :D

In the end, I took out the washers, and ground them thinner. No issues at all now!
Mick F. Cornwall
slowster
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Re: Chain slipping Between Chainrings

Post by slowster »

Brucey's thread with information about STI trim positions is in Too Good To Lose - viewtopic.php?t=124598. I note that the chart posted by Network Man in that thread refers to different 'Tension Adjustment Positions' depending upon the particular model, which I don't understand, but which seems to indicate that there is another variable which might affect shifting.
roubaixtuesday
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Re: Chain slipping Between Chainrings

Post by roubaixtuesday »

Am struggling to see how derailleur setup could possibly cause this issue - once unshipped from the big, surely it should nicely pick up the middle regardless?

Also very sceptical on the cable run theories. Tandem probably has external cabling which regardless of the run will likely have no significant difference to a solo, and much less issues than internal cabling.

Likely something wrong with the chainring setup? Washers, spacing, incompatible with chain...?

If nothing is apparent on talking to Spa, try changing the chain perhaps?
peetee
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Re: Chain slipping Between Chainrings

Post by peetee »

Is the nylon skid pad on the inside plate of the front mech in good order? If it is worn the gap is too large and adjustment for a good change up may mean the outer plate is too far out for a clean change down. It might have been ok on a previous chain set with profiled and worn teeth that provided less of an obstruction to sideward movement of the chain.
NB: this is my current and only theory. Please ignore my first post made at the end of a hot and exhausting day on the trails. (Bad Peetee, naughty Peetee :oops: :cry: )
The older I get the more I’m inclined to act my shoe size, not my age.
slowster
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Re: Chain slipping Between Chainrings

Post by slowster »

In the thread on STI trim click settings, Brucey linked to this document - https://si.shimano.com/pdfs/dm/DM-GN0001-21-ENG.pdf, which he said "is the information you really need which explains how the trim clicks are sequenced and how to adjust the system." The details for front road triple derailleurs are on page 60 onwards.

The troubleshooting charts in the document typically advise to "Loosen the cable" "If shifting is difficult from the largest chainring to the middle chainring.".

Does the STI have a T-trim position, i.e. a trim position in the large ring, and if so are the shifts to the middle ring the same whether from the standard position or the trim position?
zenitb
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