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I was advised, on a cycling forum, that the chain length as shown in these photos was just fine and I should leave it be. I was of the opinion that I ought to remove at least one link because the derailleur body was sitting much higher with the new chain that it was with the old chain and I would value a second opinion. BTW, the large/large setting is fine with a long-armed derailleur pointing at roughly the 5 o'clock position.

Here is a photo of the chain in the small/small configuration:

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Here is a close up of the derailleur.

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Here is the derailleur as it was on the old chain and how I think it ought to be on the new chain...which I think would be remedied by the removal of one link

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It's technically OK the way it is now, but if the derailleur pulley arm is at the 5 o'clock position in big/big like you say, then it sounds like you could take out a link or two.

However, be aware that the ability to shift to big/big is the overarching goal. The only problem you have right now is that the slackness in small/small could result in a little bit of chain bouncing around when riding in rough terrain. If you were to take out too many links resulting in the inability to shift to big/big, then the downside becomes catastrophic damage if you attempt to shift to big/big while under any kind of load. You'd be breaking something such as your derailleur, chainring, or cassette.

So if you do go ahead and take out any links, confirm the ability to shift to big/big before riding. This test includes a shift from 2nd largest cog to largest cog while in the big ring, and also a shift from small ring to big ring while in the largest cog.

Or another thing to confirm is simply compare the length of the old chain to the new chain while off the bike. If the old chain was fine, that that will tell you for sure what to do if the lengths don't match (ignoring chain stretch in the old chain, it's the number of links that matters).

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  • You can also use a calculator and see what it suggests. E.g: bergfreunde.eu/chain-length-calculator (note that your pulleys probably are 11T for result adjustment). Commented 11 hours ago
  • Thanks so much for that detailed response. That chain link calculator will not accommodate my 470mm chain stay length; it maxed out at 460mm. Using another online calculator, it returned 114 links as the size my chain should be. Counting the outer links on each chain and doubling it, I get 50/116 on the old chain and 60/120 on the new one. rollmassif.com/chain-link-calculator Commented 7 hours ago
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The best way I have found to size a chain--and the method described in Shimano's Dealer Manuals for their rear derailleurs--is the wrap method. You take the chain while it isn't woven thru the derailleur and place it on the large chainring and largest cassette cog. Orient the chain so that it is tight and that it comes together at the backside of the large cassette cog. There will be an excess of chain links past where the ends of the chain come together. You then add 2 or three links* from where the chain comes together on the back of the cassette to determine where the chain should be broke. If you're using a quick link to rejoin the chain, you'll need both ends of the chain to be inner links (the quick link is a set of outer link plates, it also counts as one link past the where the chain wrap comes together).

Here's some screenshots of rear derailleur install instructions from Shimano for clarity. Note, the first photo's information of adding 2-3 links pertains to your situation. The second photo is from Shimano 12 speed rear derailleur instructions and is included here to better show the chain wrap method. You do NOT need to add the number of links shown here in your system. You'll use 2 or 3, with a quick link counting as one and the other plus 1 or 2 depending on what you need for a termination (inner or outer). chain size

chain size 12s

Based on your photo's, I think you're fine, but obviously based on the numbers provided in your comment, your new chain has quite a few more links than the old chain. The wrap method works best because it incorporates the length of the chain stays in its measurement. Given any bike with seven to 11 speed systems, the chain wrap +2-3 links method yields a correctly sized chain.

*By "links" here I really mean half links: an inner link=1 the outer link plates =1 use of a quick link counts as 1, though it usually is not yet on the chain being wrapped. Technically, one chain link is one inner PLUS one outer link, however this is not what we count in the above method, which counts ½ links as one whole number.

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