Replacing chain on old 7-speed

[RhythMick]

Old Giant hybrid, inherited, plan to replace it over next few months. Pleasantly surprised with how well it rides, would like to keep it going so gradually working through cleaning and maintenance tasks.

Chain tool reports that chain is well overdue for replacement, no surprise there. I doubt it's ever been replaced. I have a few questions though.

What makes a chain a 9-speed vs a 7-speed? My instinct would be to go for a better make and they don't seem much more expensive, but the SRAM in Halfords at £13 was marked as a 9-speed.

I bought the Crank brothers multi tool with the chain tool, should be up to the job right? Never changed a chain but researched on web and you tube.

If the chain is stretched and has been for some time then presumably the cassette and front cogs are likely worn too right? Bearing in mind I'm keeping it going not upgrading, at what point do these also need replacing and how do you tell? Is there a danger that a new chain on old cogs will actually be worse than it is now? The bike is actually running just about acceptably, a few slips and changing isn't perfect. Of course as soon as i ride a good bike I'm sure my view of the Giant will change...

Anyway, as always grateful for advice before i leap in.

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[summerdays]

If you are only keeping it going then I would be tempted to leave it as it is, if it is running fine at the moment. You are probably right that the other bits would need replacing at the same time. As for when they need replacing, look at them closely - the curves when new are approximately symmetric, whereas once they are worn they become asymmetric - bit like sharks teeth.

As for speed - a 9 speed is slightly narrower. You want a 7/8 speed chain. (I use SRAM and like them).

Post a photo if you like of the worn bits.

 

[Brommyboy]

You can only fit a 6/7/8 speed chain - the others are narrower! You will also need to fit a new rear cassette and, possibly, a new chainset, as the old teeth will have worn to match the chain. Use a basic Sram chain, the top-of-the-range do not last longer as they are usually thinner and lighter weight! For my bikes, the basic Sram gives about 6000 miles on the Brommy, and perhaps 8000 on the tourer. Both change perfectly.

 

[RhythMick]

Thanks both. A bit more research( lord bless Sheldon Brown) indicates i probably have a screw on freewheel cassette rather than a freehub. Think will leave it.

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[albion]

A chain is £5.40 on Amazon.A screw-on will be no more than £10 if need be.It is cheap technology.

 

[mickle]

You can only fit a 6/7/8 speed chain - the others are narrower! You will also need to fit a new rear cassette and, possibly, a new chainset, as the old teeth will have worn to match the chain. Use a basic Sram chain, the top-of-the-range do not last longer as they are usually thinner and lighter weight! For my bikes, the basic Sram gives about 6000 miles on the Brommy, and perhaps 8000 on the tourer. Both change perfectly.

A nine speed chain will run perfectly well on a seven or eight speed block. There's no reason to do so, but it'll work fine.

And top of the range chains do last longer because what increases the costs is the number of manufacturing processes, which is mainly higher levels of plating on inner and outer plates.

 

[RhythMick]

A chain is £5.40 on Amazon.A screw-on will be no more than £10 if need be.It is cheap technology.

Yeah the parts are cheap no question. Worried about changing the screw on cassette though especially if it's been there for may 15 years untouched. Guess it would be worth trying to strip it down to see if it's going to budge.

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[fossyant]

KMC chains are great. I run a Dura Ace 9 speed on a Dura Ace 8 Speed system, as the chain was easier to get, and it has less rub on the front mech.

KMC on the other 3 bikes.

 

[RhythMick]

Front and rear cogs attached.