Hi,
I have recently purchased a mid-80s Colnago, it has super record transmission, and the chain is on the way out. It has a 7 speed cluster, which I assume is not original, and I'm thinking of replacing with a 6 speed, as the offset seems wrong too.

My question is what chain is recommended? Do I have to get a campy one? What brands are recommended? I see 11 speed chains, does that mean you can get 11 speed clusters? Yikes! I used to race, however I have a 30 year gap in my knowledge of bikes, but I'm back on the saddle and loving it!

Cheers!

Oh welcome.
We don't call them clusters anymore.
You have a freewheel, or a freehub/cassette... which is it?... most likely it's a freewheel.
What is an offset?
Replace chain with 8 speed chain.
BTW, you cannot put an 11 speed cluster on your bike.
Go to this website:
Sheldon Brown-Bicycle Technical Information

Yup, for six or seven or eight cog freewheels or freehubs, go with an eight speed chain, Schram being my personal choice, thanks to easy breaking for maintenance purposes.

And, yes, nine, ten or eleven speed chains will not fit your "clusters". To that, add this...

If you chain is worn, how about your crank rings and the freewheel cogs? They too could be worn, making a new chain a poor fit. Perhaps you would be wise to send us some good clear detailed pictures of your cogs and rings. Armed with those, more precise help might be available here.

+1 on Welcome to the Forum.

Any 8-sp chain will do, or even a single speed chain in most cases.
I like the SRAM and KMC 8-sp chains; cheap, reliable, nice looking.

They were called clusters and cogsets long ago, before freehubs came out and made calling them freewheels more confusing that it should be.

Glad to have you back on the road. Be safe out there.

Wow, thanks so much for the welcome and replies, I shall try to remember about the freewheels! By offset I mean, the freewheel seems too close to the frame, and could be closer to the spokes, and I figured a six speed would be narrower and closer to the centre of the bike. At the moment, when it's in the smallest cog, it's maybe a mm away from the stay.

I'll take some pics, perhaps you can date it for me too, and thanks again, I am loving it, joining a club soon, as soon as I get a few long rides under my belt.

If it doesn't rub its not too close!!

Ha ha yes, I do know what you mean, but we're talking 1-2 mm from the stay, like the chain is juuust squeaking past. Anyhow, having taken the derailleur apart and cleaned it up I realised the stay is slightly bent in, so I will have a go at persuading it this weekend and see what that does, as well as a new chain

Check whether you might have shims between the hub and the fW you can remove without the FW getting too close to the spokes. Also check the spacing between the cogs on the FW. 7 speed FWs should have narrower spacing between the cogs having the wrong spacers any place between the cogs can bump out the cogs too close to the rear stays. I'd be checking the smallest cog especially as they are usually screwed on to the second cog and the 7 and 6 speed smallest cog will be made differently to have the proper spacing.
Also make sure you use a narrow chain with a 7 speed FW, so it will shift properly.

+1 ^^, amen to this.

When setting up a rear hub axle setup, spacers and all, the shorter drive-side axle extension reduces the bending load on the axle, while having the cogs out more toward the drive-side also improves the chainline angle situation, especially when using the entire range of cogs while riding in the larger chainring up front.
Seven-speed freewheels are also a better choice than 6-speed freewheels for the greater variety of ratios and quality levels in the current market. It's getting harder to build or find a useful 6-speed freewheel for a versatile, high-performance road bike imo.

Depending on the bike's crankset and freewheel, a 9-speed chain often gives the most-forgiving shifting action while also not requiring that the front derailer position be "trimmed" as the chain is shifted across the range in back. 9-speed chain is my first choice where a 7-speed freewheel is used. 9-speed chain costs more, but is really, really worth it for the improvement in many instances, as long as it also gets along with the bike's chainring spacing.

Careful with that. Colnagos don't grow on trees. Is the whole stay bent, or just the dropout?

Wow, again I'm so grateful for all the feedback, I will be having a good look at the freewheel this weekend, seems like there's always something to tinker with, not that I'm complaining!

Yeah I'm probably just going to have a look and go "nope", anything major will wait for the re-paint

83 Colnago with 6 speed:
[IMG]P9161254N by superissimo_83, on Flickr[/IMG]

With 7 speed:
[IMG]PA241417 by superissimo_83, on Flickr[/IMG]

I'm not even going to post mine, it is shamefully filthy right now. I'm going to clean it up again over the weekend and compare to these, thanks.