Chain slipping Between Chainrings

For discussions about bikes and equipment.
zenitb
Posts: 832
Joined: 7 Aug 2018, 9:59pm
Contact:

Re: Chain slipping Between Chainrings

Post by zenitb »

iandusud wrote: 22 Jun 2022, 7:48pm ..... 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. ....
I also have this problem Ian. My 11 year old viking tandem now has a 10 speed Shimano setup which has a huge range and is generally great. For now I still have the original 8 speed Altus ("SIS") front mech and corresponding Altus flat bar index shifter. My cranks are the 160mm length Thorn (SJS) tandem cranks broadly similar in configuraton to your Spa ones (ie 110 BCD). If I recall correctly the rings are from Spa..so essentially a very similar setup.

On some changes from big chainring to middle chainring the chain would just "ride" the teeth of the middle ring...clicking but not dropping onto the teeth .. which sounds like what you have.

That first 10 speed chain had had some bad crunches around the bottom bracket over time finally refusing to hold gears at all..while miles from home. By the roadside I discovered the chain was twisted out of true in one section and i used a thin allen key and a thin screwdriver inserted in adjacent chain links to twist it straight and get back home. I wondered how long it had been twisted but it certainly explained some of the weird shifts i had been having.

I have a new 10 speed chain and block now and all seems well with decent big to middle changes although the front indexing is clearly not really right with a quick "two down one up" being required some times

I am now planning to install a non index shifter for the front mech..probably an old Ultegra bar end shifter mounted on the flat bar "bar end" (if you see what I mean). I think using the old "original with cheap tandem" Altus left hand front index shifter is just too brutal on the chain. A non index shifter will hopefully be more gentle.

Not sure this is your issue but check chain twist !!!

I will be watching the thread with interest...great post...
iandusud
Posts: 1577
Joined: 26 Mar 2018, 1:35pm

Re: Chain slipping Between Chainrings

Post by iandusud »

Thank you for all the replies. I'll try and cover all topics raised. The cables and outers are all new and very carefully cut and set up (I'm very conscious of the need for this, particularly on a tandem). The front mech is new so not worn. Chain was recently replaced as is in good condition. I am getting all the trim positions. As mentioned by someone else, my expectation has always been if the chain is unshipped from the big ring it should automatically engage with the middle ring (unless of course the inside plate of the front mech is preventing it). This does not appear to be the case. I have been working on bikes (for many years professionally) for over 40 years and am aware of the need for careful set up of front mechs, particularly with indexing. However I have never come up with one as finickity as this one. Having fiddled with it some more I think it is working reasonably well but I think I'm likely to get the chain rubbing on the outer plate of the front mech when using the big chainring and smaller sprockets. If I adjust the cable to irradiate this I will likely get the problem of the chain not engaging the middle ring and/or difficulty dropping onto the inner ring. Had I built this bike up from new I would have without a doubt fitted bar end levers but I bought it second hand with the Tiagra 4703 set up and, to be fair, on the whole it has performed well.
peetee
Posts: 4292
Joined: 4 May 2010, 10:20pm
Location: Upon a lumpy, scarred granite massif.

Re: Chain slipping Between Chainrings

Post by peetee »

Is it possible the middle ring has been fitted back to front?
The older I get the more I’m inclined to act my shoe size, not my age.
bgnukem
Posts: 694
Joined: 20 Dec 2010, 5:21pm

Re: Chain slipping Between Chainrings

Post by bgnukem »

I had a similar issue with a basic version of the Spa triple, i.e. the one with two steel rings fitted (inner and middle), in that a 9-speed chain would fall into the gap between the big and middle rings.

This was resolved by machining some material off the spider (and granny ring bosses) to bring the rings closer together. Oddly, I am running the same chainset but with Spa aluminium alloy rings on another bike with 9-speed without issues.

I suspect either quality control variations or that the steel rings were thinner than the ali rings, but I think the triples are based on the old Sugino XD2 cranks and so perhaps were designed for 7/8-speed chains.
iandusud
Posts: 1577
Joined: 26 Mar 2018, 1:35pm

Re: Chain slipping Between Chainrings

Post by iandusud »

bgnukem wrote: 23 Jun 2022, 12:14pm I had a similar issue with a basic version of the Spa triple, i.e. the one with two steel rings fitted (inner and middle), in that a 9-speed chain would fall into the gap between the big and middle rings.

This was resolved by machining some material off the spider (and granny ring bosses) to bring the rings closer together.
This same idea has occurred to me although I think I would only need to bring the two outer rings closer together. 1 mm would do the trick.
slowster
Moderator
Posts: 4629
Joined: 7 Jul 2017, 10:37am

Re: Chain slipping Between Chainrings

Post by slowster »

I would definitely give Spa a call. It might be that although the chainsets as sold are suitable for a wide range of different speeds as advertised on the website, their mechanics may have experience and knowledge of how to fine tune them to make them work better for particular configurations or in the event of a more demanding set up, such as on a tandem.
User avatar
Mick F
Spambuster
Posts: 56359
Joined: 7 Jan 2007, 11:24am
Location: Tamar Valley, Cornwall

Re: Chain slipping Between Chainrings

Post by Mick F »

Either use a wider chain, or grind down the spacers.
Been there, done that.
Nowt to do with indexing.
Mick F. Cornwall
bluespeeder
Posts: 101
Joined: 9 Nov 2021, 3:40pm

Re: Chain slipping Between Chainrings

Post by bluespeeder »

I agree with the above. I had this happen with a 9spd chain where the small ring would slip a quarter turn before engaging. No problems with any 8spd chains I have used. I could have messed with the spacing but easier just to use a wider chain.
roubaixtuesday
Posts: 5814
Joined: 18 Aug 2015, 7:05pm

Re: Chain slipping Between Chainrings

Post by roubaixtuesday »

slowster wrote: 23 Jun 2022, 2:24pm I would definitely give Spa a call. It might be that although the chainsets as sold are suitable for a wide range of different speeds as advertised on the website, their mechanics may have experience and knowledge of how to fine tune them to make them work better for particular configurations or in the event of a more demanding set up, such as on a tandem.
Whilst the consequence of this might be more severe on a tandem, I don't at all understand why it being a tandem is "more demanding" from the POV of the basic function of a chainsaw? It's identical surely?
iandusud
Posts: 1577
Joined: 26 Mar 2018, 1:35pm

Re: Chain slipping Between Chainrings

Post by iandusud »

slowster wrote: 23 Jun 2022, 2:24pm I would definitely give Spa a call. It might be that although the chainsets as sold are suitable for a wide range of different speeds as advertised on the website, their mechanics may have experience and knowledge of how to fine tune them to make them work better for particular configurations or in the event of a more demanding set up, such as on a tandem.
I called Spa this morning and had a chat. They were happy that this chainset works with all setups up to 11 speed.
iandusud
Posts: 1577
Joined: 26 Mar 2018, 1:35pm

Re: Chain slipping Between Chainrings

Post by iandusud »

Mick F wrote: 23 Jun 2022, 3:19pm Either use a wider chain, or grind down the spacers.
Been there, done that.
Nowt to do with indexing.
I assume that a wider chain (9 speed) wouldn't work with a 10 speed cassette.
iandusud
Posts: 1577
Joined: 26 Mar 2018, 1:35pm

Re: Chain slipping Between Chainrings

Post by iandusud »

roubaixtuesday wrote: 23 Jun 2022, 3:47pm
slowster wrote: 23 Jun 2022, 2:24pm I would definitely give Spa a call. It might be that although the chainsets as sold are suitable for a wide range of different speeds as advertised on the website, their mechanics may have experience and knowledge of how to fine tune them to make them work better for particular configurations or in the event of a more demanding set up, such as on a tandem.
Whilst the consequence of this might be more severe on a tandem, I don't at all understand why it being a tandem is "more demanding" from the POV of the basic function of a chainsaw? It's identical surely?
I think it is the gear cable, being longer, that adds potential issues, assuming that the gear cable has a certain amount of elasticity.
User avatar
531colin
Posts: 16083
Joined: 4 Dec 2009, 6:56pm
Location: North Yorkshire

Re: Chain slipping Between Chainrings

Post by 531colin »

Unless you have a "Carpenter drive" the triple chainset is also rather a long way from the captain who is (presumably) operating the shifters.
I found this makes it just a bit harder to sense whats going on, but perhaps thats irrelevant with indexed shifting?
Jdsk
Posts: 24635
Joined: 5 Mar 2019, 5:42pm

Re: Chain slipping Between Chainrings

Post by Jdsk »

roubaixtuesday wrote: 23 Jun 2022, 3:47pmWhilst the consequence of this might be more severe on a tandem, I don't at all understand why it being a tandem is "more demanding" from the POV of the basic function of a chainsaw? It's identical surely?
That's a serious multitool!

: - )

Shirley
slowster
Moderator
Posts: 4629
Joined: 7 Jul 2017, 10:37am

Re: Chain slipping Between Chainrings

Post by slowster »

roubaixtuesday wrote: 23 Jun 2022, 3:47pm
slowster wrote: 23 Jun 2022, 2:24pm I would definitely give Spa a call. It might be that although the chainsets as sold are suitable for a wide range of different speeds as advertised on the website, their mechanics may have experience and knowledge of how to fine tune them to make them work better for particular configurations or in the event of a more demanding set up, such as on a tandem.
Whilst the consequence of this might be more severe on a tandem, I don't at all understand why it being a tandem is "more demanding" from the POV of the basic function of a chainsaw? It's identical surely?
I am supposing that the derailleur cage may need to move with a minimum speed for a clean downshiftshift, and that too slow a movement of the cage might cause the problem that the OP is experiencing, which might in turn be caused by more friction in the cable run on a tandem.
Post Reply