Finally got a 20 tooth cog for my 69 Raleigh sports the other day. I chose 20 over 22 because I wanted a slight gearing change rather than a dramatic one.

After making the swap, I realized the axle sat dangerously close to the end of the dropouts, and I needed to lengthen the chain.

Bought a chain tool, watched the YouTube tutorial on how to use it (push the rivets "almost" all the way out and then twist and release), and proceeded to try to add a link. I had chains from two donor Raleighs (a 65 and a 67) on hand.

The holes from the first donor link were too small. The rivets wouldn't go through. The holes from the second donor link were the right size, but the rivet came all the way out and now is impossible to get "started" back in.

1. It looks as though you can't add 1 link, you have to add 2 at a time, is that right?
2. Were vintage Raleigh chains different sizes?
3. The LBS sells new chains for $60-$80. I ain't payin' that.
4. If I were to find a new chain for a reasonable price, what size am I looking for?

Thanks for your patience!

1 -> Correct. There are "inner" and "outer" links, and one "gender" can only attach to the other. There exists a "half-link" for when you *really* need to add only one link to a chain, but with horizontal dropouts you should never be that desperate.

2 -> I have no specific knowledge of Raleigh chains, but in general the ability to add links from one chain into another seamlessly is not guaranteed. The width of the links and the distance between them are standardized across the industry, but internal dimensions like the size of the link pins can vary.

3 -> O_o 3 ideas: The price includes moderately-expensive labor, they were offering you a really fancy (and probably incompatible) racing chain, or they wanted to take you for a ride. My guess is #1.

4-> For a Sturmey-Archer geared hub bike, you want a 1/8" chain. This'll also be called "single speed" chain. https://www.amazon.com/KMC-Z410-Bicyc...dp/B0013CH2M8/ is an example of the type of chain you want.

1) two half links at a time
2) the original chain was 1/8"
3) you're mistaken or they only have the most expensive pintle chains available at the moment
4) I really like the SRAM PC-1, but I also use the KMC 1/8" drive SS chains

And, yeah, once you pop that rivet all the way out it's so frustrating I just abandon it and use that chain as a donor in the future.

OK, went to another LBS and got an SRAM PC1 Nickel 1/8" chain for $16.

Laid out the old chain next to it and measured +2 links and separated the chain at that point. Mounted rear wheel and it was still too long by 2 links. Took out the 2 links and now the rear wheel is all the way back in the dropouts and rubbing on the rear reflector bolt. Light sprinkles of rain started to fall. (I was working outside)

Took off the rear reflector and tried to file down the bolt. Made a mess. Found another bolt. Put it all back together just as it started to pour.

No small adventure changing this cog.

You need an offset lhalf-link. This will allow lengthening by only a single link. Scroll down to the bottom of this page: https://sheldonbrown.com/harris/fixed.html

Any 1/8" (width) chain will do. These bikes are easy on their chains.

The same thing happened to me when I tried to lengthen my 50-year-old chain, so I'm using a new chain now.

Let your chain run loose until you get the half link.

Ah, the half-link. I should have known, "when in doubt, go to Sheldon."

The new SRAM PC1 chain has the rear wheel sitting almost all the way back in the dropouts and chain tension is normal. Any problem with running it this way?

What color is your bike? https://www.amazon.com/KMC-Z410-Bicyc.../dp/B001RPU3P4
https://www.amazon.com/KMC-545-1265-L.../dp/B001CNC2UU for the half link.

There's nowhere to go if you need to tighten up your chain in the future.

Might be easier to get a 21T or 22T cog...

Sounds perfect to me! You might have room to go up to a 21 or 22 if you want to later.

Black.

Also thanks to ColonelJLloyd. Noticed the chain is running a bit close to the back stay or strut or whatever those things are called. Tomorrow I'll mess with my new deep dished cog, maybe flip it or move the spacers. Hate that circleclip, tho.