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Shimano 6-7-8 chain connecting pin and careless installation
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 |
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#2
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Shimano 6-7-8 chain connecting pin and careless installation
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/cyclin...9830558543.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 |
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Shimano 6-7-8 chain connecting pin and careless installation
On 15 Feb 2006 15:04:21 -0800, "Nate Knutson"
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. |
#4
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Shimano 6-7-8 chain connecting pin and careless installation
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" writes: What you should do is complicated by another thing about Shimano chains - they say in their manual (http://bike.shimano.com/media/cyclin...9830558543.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. |
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