Author Topic: Chain Tension?  (Read 3455 times)

DONE

  • Newbie
  • *
  • Posts: 18
Chain Tension?
« on: July 24, 2013, 03:32:45 pm »
I have just fitted a 19 tooth rear sprocket onto my new Nomad (500 km) in order to help me up the hills on an upcoming Lake District trip. New combination 40-19 old 40-17, when refitting the chain it is quite tight about 1-2mm max up and down play. (the eccentric bottom bracket was loosened off and rotated into its shortest position pre refitting the chain). Is this chain tension too tight? Do I need a new chain, or are extra links available? I'm not sure if the complete chain would have been used when Thorn set up the bike originally or whether they shorten the chains dependant on gear setup.

Andybg

  • Hero Member
  • *****
  • Posts: 829
Re: Chain Tension?
« Reply #1 on: July 24, 2013, 03:46:57 pm »
Sounds a bit too tight to me. The chains are adjusted in length to the gearing so it is normal to have to change the chain length if you are changing the gearing. I am not sure if it would be cost effective to buy a few links but if you buy a replacement chain it may be long enough to "steel" a couple of links for this chain and then have a spare.

If you count the links you are using (eg 108) then buy a 114 then you can make two 110's out of them.

While you are at it, it may be worth adding a "missing link" (or even two to the extended chain)

I would go with a tension that seems on the loose side but that cannot come off (hope that makes sense

Andy

DONE

  • Newbie
  • *
  • Posts: 18
Re: Chain Tension?
« Reply #2 on: July 24, 2013, 04:23:10 pm »
Thanks Andy,  I will buy a replacement, same spec chain then be able to make a complete spare as you suggest.
Don

Andre Jute

  • Hero Member
  • *****
  • Posts: 4068
Re: Chain Tension?
« Reply #3 on: July 24, 2013, 09:09:24 pm »
Thanks Andy,  I will buy a replacement, same spec chain then be able to make a complete spare as you suggest.
Don

A split and rerivetted chain is always weakest at that spot, especially the modern chains with "special" techniques of pre-shaping and folding over the head.

I prefer the method of lengthening a chain by adding quick links, especially where the chain is still nearly new and can be expected to have a long life. That also makes it easier to split and adjust the chain if necessary.

Andre Jute

DONE

  • Newbie
  • *
  • Posts: 18
Re: Chain Tension?
« Reply #4 on: July 25, 2013, 10:01:10 am »
Thanks Andre, I have bought some additional "missing links" in order to join the additional length of chain.
Don

il padrone

  • Hero Member
  • *****
  • Posts: 1322
Re: Chain Tension?
« Reply #5 on: July 26, 2013, 09:12:47 am »
A split and rerivetted chain is always weakest at that spot, especially the modern chains with "special" techniques of pre-shaping and folding over the head.

Re-rivet it with the special Shimano joining pin and I've never known of any problem. If you try to re-join it wit the old rivet, well yes, then it is on a ticking schedule to break again.
« Last Edit: July 26, 2013, 10:29:30 am by il padrone »

Andre Jute

  • Hero Member
  • *****
  • Posts: 4068
Re: Chain Tension?
« Reply #6 on: July 26, 2013, 10:33:02 am »
Re-rivte it with the special Shimano joining pin and I've never known of any problem. If you try to re-join it wit the old rivet, well yes, then it is on a ticking schedule to break again.

Sure, but I wonder how many Rohloff-equipped bikes run on Shimano chains.

Andre Jute

il padrone

  • Hero Member
  • *****
  • Posts: 1322
Re: Chain Tension?
« Reply #7 on: July 26, 2013, 11:23:16 am »
Sure, but I wonder how many Rohloff-equipped bikes run on Shimano chains.


Those that don't run SRAM, Wipperman, KMC or similar and use their proprietary quick-links. Problem solved.

Andre Jute

  • Hero Member
  • *****
  • Posts: 4068
Re: Chain Tension?
« Reply #8 on: July 26, 2013, 11:29:53 am »
There's also the question of whether, what with today's puncture-proof tyres, good tubes, and longlasting chains, a really good quality chainsplitter is justified. The thing is expensive and presumes a certain amount of skill which you don't learn with very infrequent use. It's valid to wonder whether the art of roadside chain-splitting and -splicing is dead or merely dying.

Andre Jute

DONE

  • Newbie
  • *
  • Posts: 18
Re: Chain Tension?
« Reply #9 on: July 26, 2013, 09:50:09 pm »
Chain is a KMC X1 designed for Rohloff, so I have ordered the correct missing links to rejoin chain. With a virtually new chain I didn't think that it was worth compromising on a quality repair.
Don