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I'm pro-actively replacing the chain on my son's bike (the first time I neglected this cost me dear for replacement of derallieur, cassette and cranks at the LBS) which is used daily for commute to school (about 8.5 miles/day round trip). The previous chain was a KMC which came with a quick-link, this time I am back to the original.

The new chain is Shimano 8S CN-HG71, and comes with a connecting pin rather than quick-link. I'm looking at the Dealers Manual DM-GN0001-23-ENG.pdf pages 68 onwards. I have all the necessary tools.

On page 70 it states: As illustrated in Fig. [A], we strongly recommend to set the connecting pin in the hole of the outer link on the front side in the direction of travel. The chain’s level of strength is enhanced compared to the method in Fig. [B]

This is accompanied by an image but unfortunately, rather than clarify, this has left me with a level of doubt.

The picture shows the chain broken below the crank therefore travelling right-to-left, if the figs. [A] and [B] correspond to this then they are the opposite way around to what the words suggest. Or is the pulling-force being applied from the right-hand-end of those diagrams (so they are not a direct zoom-in to the crank diagram, despite that being suggested)?

NOTICE from page 70

Image credit: Shimano

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  • I've never seen this before, and I doubt that it makes much difference.
    – Daniel R Hicks
    Commented Mar 8, 2020 at 13:07
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    Essentially you want to break/rejoin the chain at the leading pin of an outter link. The diagram has the break in the chain on its bottom run and is travelling right to left. Thus, the correct placement is thru the left hole of the outter link as viewed from the bike's drive side.
    – Jeff
    Commented Mar 8, 2020 at 22:08
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    TBH I've never noticed a difference which way round the chain is joined, so while one way might be "technically better" the practical difference is likely to be small.
    – Criggie ♦
    Commented Mar 8, 2020 at 22:25
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    Don't use the Shimano pin. Pop out the rivet hold the outer plates on the "open" end of the chain, take off both outer plates, and reuse the quick link from the old chain.
    – Andrew Henle
    Commented Mar 9, 2020 at 9:28
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    @Carel Quick links don't have any real wear surfaces - it's the rollers at each joint that undergo most wear, and the only reason KMC links aren't "reusable" is SRAM has a patent on "reusable" links. I have some 10-speed KMC links that have been reused for probably close to 10 years over many chains.
    – Andrew Henle
    Commented Mar 11, 2020 at 15:26

2 Answers 2

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The way they've worded and shown this in diagrams has always been a little nutty. You can pretty much see what they mean if you max zoom on the full res pdf though.

You are looking at the drive side of the bike. You are holding the chain stretched end to end between your hands. Your left hand holds the end that terminates in an inner link, your right one with an outer link. Put the outer link end on the crank and through the front derailleur as applicable. Put the inner link end through the rear derailleur. Do your sizing on the inner link end such that you're still left with an inner link when done. Then connect it all with the one-time pin.

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    OK. So at the join, the inner link is doing the pulling when pressure is applied on the pedals. Thanks!
    – Ed Randall
    Commented Mar 8, 2020 at 10:33
  • @EdRandall - All links pull equally.
    – Daniel R Hicks
    Commented Mar 9, 2020 at 1:44
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    @EdRandall, the inner link may be pulling, but by the Newton's 3rd law the next link is pulling equally hard on it in the opposite direction. I strongly suspect this all is a fallacy. However, there is a difference when the pin (or rather its roller) is engaged on a tooth. With the suggested connection (A), it is the whole inner link that transfers the force. With (B), the force is transferred via the pin to the outer link, which is less desirable if the connection is not perfect.
    – Zeus
    Commented Mar 12, 2020 at 0:11
  • @Zeus That is really astute, thanks for pointing that out.
    – Nathan Knutson
    Commented Mar 12, 2020 at 3:39
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I would suggest that the text is meant to say:

"We strongly recommend to set the connecting pin in the hole of the outer link on the leading side in the direction of travel"

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    Just an arrow at the top of the inset diagrams stating 'Direction of chain travel' would have disambiguated it sufficiently.
    – Ed Randall
    Commented Mar 9, 2020 at 14:55

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