Advice on chain(s) for IGH tandem

For discussions about bikes and equipment.
Post Reply
User avatar
RickH
Posts: 5377
Joined: 5 Mar 2012, 6:39pm
Location: Horwich, Lancs.

Advice on chain(s) for IGH tandem

Post by RickH »

The chains on my Circe Helios tandem are looking worn (the timing chain has a tensioner rather than an EBB & it is now touching the frame) so I'm looking to replace them soon.

Current chains have PC-830 (SRAM I presume?) stamped on them which, I gather from the chain wear topic, aren't the best.

The rest of the set up (basically as specced from new ~3 years ago, if it is of help) is a triple chainset (well 2 actually but the front only has an inner & a bashguard) with the inner running the timing chain & the middle (39t) and outer (52t) running as a double on an Alfine 8 with a 2 jockey wheel tensioner. Currently running a 16 tooth sprocket, but I'll probably swap to an 18 or possibly a 20 while I'm doing the chains - mainly to drop the bottom gear for the steepest of the hills that are hard/impossible to avoid round here. It doesn't do high mileage & is mainly a "grandchildren transporter" (stoker aged 5½ with his 2½ year old sister in a seat on the back) & occasional load carrier.

Would there be any advantage/disadvantage in swapping the inner chainrings for 32t (rather than the current 30t), primarily to give the tensioner on the timing chain a bit more room to work, while I'm at it?

Advice greatly appreciated.

Rick.
Brucey
Posts: 43113
Joined: 4 Jan 2012, 6:25pm

Re: Advice on chain(s) for IGH tandem

Post by Brucey »

larger timing chain chainrings give lower chain tension loads and are generally a good thing.

Check that they fit in the places where they need to, but I'd suggest that you get some 1/8" chains instead of 3/32" ones; many 1/8" chains (e.g.from Parker mail order), are cheaper, wear better, run smoother, last longer, and are usually easier to join, too.

They run fine on 3/32" chainrings BTW.

cheers
-------------------------------------------------------------------------------
~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~
rjb
Posts: 4373
Joined: 11 Jan 2007, 10:25am
Location: Somerset (originally 60/70's Plymouth)

Re: Advice on chain(s) for IGH tandem

Post by rjb »

Brucey wrote:larger timing chain chainrings give lower chain tension loads and are generally a good thing.

Check that they fit in the places where they need to, but I'd suggest that you get some 1/8" chains instead of 3/32" ones; many 1/8" chains (e.g.from Parker mail order), are cheaper, wear better, run smoother, last longer, and are usually easier to join, too.

They run fine on 3/32" chainrings BTW.

cheers


+1 and you can get 1/8" chains in large asda stores for £4 so pick a couple up next time you go shopping. (you will probably need 2 as timing chains are usually longer than standard) :wink:
http://direct.asda.com/Bell-Uni-Bike-Ch ... lt,pd.html
At the last count:- Peugeot 531 pro, Dawes Discovery Tandem, Dawes Kingpin, Raleigh 20, Falcon K2 MTB dropped bar tourer, Longstaff trike conversion on a Falcon corsa. :D
User avatar
RickH
Posts: 5377
Joined: 5 Mar 2012, 6:39pm
Location: Horwich, Lancs.

Re: Advice on chain(s) for IGH tandem

Post by RickH »

Thanks

Are there likely to be any problems with 2 1/8" chains running on adjacent chainrings? As I say, the timing chain runs on the inners of standard modern triple chainsets (can't see any brand names on them though).

Rick.
rjb
Posts: 4373
Joined: 11 Jan 2007, 10:25am
Location: Somerset (originally 60/70's Plymouth)

Re: Advice on chain(s) for IGH tandem

Post by rjb »

Argh! missed the bit about the timing chain being on the inside ring of the triple. The 1/8" chain would have been for the timing chain only but I don't know if it would clash with the normal 3/32" drive chain. I suggest you check the current clearance when the 2 chains are closest and assess the situation. If the gap is more than 2mm you may be ok to fit an 1/8" timing chain to the inner rings only. :wink:
At the last count:- Peugeot 531 pro, Dawes Discovery Tandem, Dawes Kingpin, Raleigh 20, Falcon K2 MTB dropped bar tourer, Longstaff trike conversion on a Falcon corsa. :D
Brucey
Posts: 43113
Joined: 4 Jan 2012, 6:25pm

Re: Advice on chain(s) for IGH tandem

Post by Brucey »

RickH wrote:Thanks

Are there likely to be any problems with 2 1/8" chains running on adjacent chainrings? As I say, the timing chain runs on the inners of standard modern triple chainsets (can't see any brand names on them though).

Rick.


if there is a problem you may be able to space the chainrings further apart. I was surprised to find recently that a nominally 1/8" chain would actually run OK on a 6s freewheel. They do vary though.

On a double chainring, the spacing is wider again (than a 6s freewheel), to allow for the chain angle onto a freewheel or cassette, which you don't have to worry about in the same way. So I think the chain will be OK on the double, but you might have to put some washers behind the timing chain chainring on the rear crank.

cheers
-------------------------------------------------------------------------------
~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~
Post Reply