Shimano 6-7-8 chain connecting pin and careless installation

[Ben Pfaff]

I installed a new Shimano HG-50 chain on my old 5-cog bike. This
chain has a "special connecting pin" (Lennard Zinn calls it a
"subpin") that is supposed to be used only once and then a new
one installed after it is removed. However, just after I
installed it, and before I broke off the "guide" part of the pin,
I realized that I'd routed the chain the wrong way, so I removed
the pin, rerouted the chain, reinstalled the pin, and broke off
the guide.

Should I buy a new pin?

Also, this chain is labeled for use with a 6/7/8 cog system. The
bike shop said it should work okay for 5 cogs too. It seems to
work fine. Any disagreement?
--
"Welcome to the Slippery Slope. Here is your handbasket.
Say, can you work 70 hours this week?"
--Ron Mansolino

 

[Nate Knutson]

Ben Pfaff wrote:
> I installed a new Shimano HG-50 chain on my old 5-cog bike. This
> chain has a "special connecting pin" (Lennard Zinn calls it a
> "subpin") that is supposed to be used only once and then a new
> one installed after it is removed. However, just after I
> installed it, and before I broke off the "guide" part of the pin,
> I realized that I'd routed the chain the wrong way, so I removed
> the pin, rerouted the chain, reinstalled the pin, and broke off
> the guide.
>
> Should I buy a new pin?

It's actually kinda tricky.

The connecting pin is supposed to never be removed after it's
installed, and the outer plates are supposed to never go through more
than one removal of a normal pin and re-installation of a connecting
pin. Future replacement pins are supposed to take the place of regular
pins. Shimano's instructions are vague about the last bit - in the
current manual, they say as much in a warning clause regarding resizing
the chain, but don't mention that it shouldn't be done ever, which
doesn't make any sense.

The reason why replacement pins (and the much smarter 2-piece removable
link systems) exist, and also the reason why outer plates should only
ever go through one insertion of anything after their original pin has
been removed, is that on modern chains, the interference fit between
pins and outer plates is tighter, and both the pins and the plates are
subject to having their sizes change during removal and/or
re-installation. Shimano connecting pins have a diameter that's chosen
to compensate for all this.

Chain breakages can result from disregarding pretty much anything
involved here.

What you should do is complicated by another thing about Shimano chains
- they say in their manual
(http://bike.shimano.com/media/cycli...nents/CN/SI-CN-7701_v1_m56577569830558543.pdf)
that they "strongly recommend" that only links oriented on the leading
end, relative to the chain's rotation, of the outer plate be removed.

Assuming you sized the chain as short as it can go and you have some
chain left over, you could buy 2 new pins, remove the outer plates that
had the original replacement pin installed twice, as well as remove the
other links necessary to satisfy Shimano's "recommendation," and in its
place use the 2 new pins to install a new section of chain that was
discarded when you sized the chain. That would be a technically correct
solution.

Another thing you could do is remove the outer plates that you
currently have the connecting pin in, and in their place install either
a SRAM 8-speed (silver) Powerlink, which neither SRAM nor Shimano say
you should do but which a lot of folks do with no problems at all. I
haven't done this on any of my own bikes (mostly because I only use
chains that have their own replacement links) and wouldn't do it a
customer's bike because I still feel it's an "at your own risk" thing
and chain breakages can be very, very bad, but in reality I wouldn't be
surprised if it's more reliable than a Shimano chain with a few
replacement links in it.

Also, there's the Super Link, which is a 2-piece link that works with
anything of the right width. I don't know if 8-speed ones are still
around.

> Also, this chain is labeled for use with a 6/7/8 cog system. The
> bike shop said it should work okay for 5 cogs too. It seems to
> work fine. Any disagreement?
> --
> "Welcome to the Slippery Slope. Here is your handbasket.
> Say, can you work 70 hours this week?"
> --Ron Mansolino

 

[Werehatrack]

On 15 Feb 2006 15:04:21 -0800, "Nate Knutson" <[email protected]>
wrote:

>Another thing you could do is remove the outer plates that you
>currently have the connecting pin in, and in their place install either
>a SRAM 8-speed (silver) Powerlink, which neither SRAM nor Shimano say
>you should do but which a lot of folks do with no problems at all. I
>haven't done this on any of my own bikes (mostly because I only use
>chains that have their own replacement links) and wouldn't do it a
>customer's bike because I still feel it's an "at your own risk" thing
>and chain breakages can be very, very bad, but in reality I wouldn't be
>surprised if it's more reliable than a Shimano chain with a few
>replacement links in it.

I use SRAM silver Powerlinks with Shimano chains all the time. I've
never had a problem with them.


The OP wrote:
>> Also, this chain is labeled for use with a 6/7/8 cog system. The
>> bike shop said it should work okay for 5 cogs too. It seems to
>> work fine. Any disagreement?

5/6/7/8 can all use an 8s chain without problems in my experience.
--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Words processed in a facility that contains nuts.

 

[Ben Pfaff]

First of all, thanks for your very detailed explanation. I think
I understand the issue now--and I wish I'd gone to a bike shop
that sold chains that don't have this problem.

"Nate Knutson" <[email protected]> writes:

> What you should do is complicated by another thing about Shimano chains
> - they say in their manual
> (http://bike.shimano.com/media/cycli...nents/CN/SI-CN-7701_v1_m56577569830558543.pdf)
> that they "strongly recommend" that only links oriented on the leading
> end, relative to the chain's rotation, of the outer plate be removed.

I'm slightly baffled by the distinction in that manual between
"link pins" and "end pins". What is the difference? Google
shows these terms appearing mostly in Shimano documentation, and
neither Shimano nor Sheldon Brown's glossary defines them. I get
the impression from Shimano's diagram that end pins and link pins
alternate along the chain, but I want to be make sure that's
correct.

> Assuming you sized the chain as short as it can go and you have some
> chain left over, you could buy 2 new pins, remove the outer plates that
> had the original replacement pin installed twice, as well as remove the
> other links necessary to satisfy Shimano's "recommendation," and in its
> place use the 2 new pins to install a new section of chain that was
> discarded when you sized the chain. That would be a technically correct
> solution.

The chain may be longer than necessary at the moment. I did not
remove any links, because the old chain the same length as the
new chain without any removing any links (this is the first time
I've replaced a chain on this bike, which I bought used).
Assuming that it is indeed longer than necessary, could I just
remove the link that has the connector pin? If I understand all
the constraints correctly, I'd push out two link pins, one on
each side of the connector pin, then install a new connector pin
to join those two together.
--
Ben Pfaff
email: [email protected]
web: http://benpfaff.org

 

[Nate Knutson]

Ben Pfaff wrote:
> First of all, thanks for your very detailed explanation. I think
> I understand the issue now--and I wish I'd gone to a bike shop
> that sold chains that don't have this problem.
>
> "Nate Knutson" <[email protected]> writes:
>
> > What you should do is complicated by another thing about Shimano chains
> > - they say in their manual
> > (http://bike.shimano.com/media/cycli...nents/CN/SI-CN-7701_v1_m56577569830558543.pdf)
> > that they "strongly recommend" that only links oriented on the leading
> > end, relative to the chain's rotation, of the outer plate be removed.
>
> I'm slightly baffled by the distinction in that manual between
> "link pins" and "end pins". What is the difference? Google
> shows these terms appearing mostly in Shimano documentation, and
> neither Shimano nor Sheldon Brown's glossary defines them. I get
> the impression from Shimano's diagram that end pins and link pins
> alternate along the chain, but I want to be make sure that's
> correct.

The "end pin" is another type of special pin with a flat, featureless
tip (compared to the dot of the replacement pin and the rectangular
blob thing of regular pins). They're only used in OEM bike assembly at
a factory where they're installed using an impact tool, and like
replacement pins they're not supposed to ever be removed.

> > Assuming you sized the chain as short as it can go and you have some
> > chain left over, you could buy 2 new pins, remove the outer plates that
> > had the original replacement pin installed twice, as well as remove the
> > other links necessary to satisfy Shimano's "recommendation," and in its
> > place use the 2 new pins to install a new section of chain that was
> > discarded when you sized the chain. That would be a technically correct
> > solution.
>
> The chain may be longer than necessary at the moment. I did not
> remove any links, because the old chain the same length as the
> new chain without any removing any links (this is the first time
> I've replaced a chain on this bike, which I bought used).

Then most likely it's quite a bit longer than it needs to be unless it
has really long chainstays and/or weird gearing. You could check this
quickly by shifting into the large/large gear and looking at the
position of the rear derailer - if it's as short as possible, it will
be pulled in the direction of the cranks quite a bit in this position.
There's a lot of info on chain length in the usual places.

> Assuming that it is indeed longer than necessary, could I just
> remove the link that has the connector pin? If I understand all
> the constraints correctly, I'd push out two link pins, one on
> each side of the connector pin, then install a new connector pin
> to join those two together.

It depends on whether you want to abide by Shimano's advice to only
have the replacement pin be installed in a certain position on the
outer plate relative to the chain's rotation. If it was installed in
that position the first time, it won't be when you do what you suggest,
and vice versa.

The position of the replacement pin relative to rotation is a pretty
frequently ignored distinction and I have no real idea how much it
matters and under what circumstances, etc. Still, as much as I love
second-guessing Shimano, chain stuff is sensitive and you really don't
want your chain to break. Your chain is probably overlong by multiple
links anyway, and if so you could just set it up the "recommended" way.