When to change chain ring or cassette

[Big T]

I use ALL my cogs and rings in equal amounts.

as it happens Mick i do exactly this all winter.

But here in Flatlandia, my 13, 14 and 15 sprockets get much more use than my 27. Also, my 39 ring gets more use than the 30 or the 52.

[Zanda]

...I looked at the chain. There is a gap on either side of many of the rings so I think the chain needs to be replaced.
But, what about the cassette or chain ring, do they need to be replaced also (hopefully not)...

After seeing your question, I wrote a webpage with information I hope will be useful to you (and others with the same question). Among other things, it explains Sheldon Brown's advice on how to measure chain wear with a ruler. (I find the readings from chain checker tools can vary between makes, so I consider them unreliable.)

http://cyclingfortransport.com/plan/mai ... hain-wear/

[meic]

I can see a small flaw in your method.

If you try and measure the distance between twelve links on a steel rule you will probably be off the scale.

[531colin]

I can see a small flaw in your method.

If you try and measure the distance between twelve links on a steel rule you will probably be off the scale.

Oh, I dunno....heres one I got out of a skip.....



that's the rule, not the bike.......
I wonder what specific purpose the rule was made for.....its 75cm long, 29 1/2 inches, calibrated in millimetres and sixteenths of an inch, its stainless (marked "rustless"....?) and apparently " standard at 68deg F."
I haven't really got a use for it, but it seemed an act of vandalism to skip it....its quite decorative, in an industrial sort of way....

[AlastairS]

I measured 12 links on my used chain at they measure 11 inches and 6/8ths from 1st centre pin in 1st link to last centre pin in 12th link.

[meic]

That is 11 and a half links and with 2/8ths of wear which is twice the limit for sprocket damage.

You might as well ride it to destruction now and then replace the lot.

[AlastairS]

Hi, I measured 12 complete links and they measure 12" exactly.
(My previous measurement (see above) was more than 11 and a half links.)

What do you think now? Alastair

[531colin]

Hi, I have the same chain on my Galaxy since I bought it 9 years ago. I don't do alot of miles each year - maybe 1000.
I looked at the chain. There is a gap on either side of many of the rings so I think the chain needs to be replaced.
But, what about the cassette or chain ring, do they need to be replaced also (hopefully not).
THe chain ring I think looks okay and the cassette looks okay to , but I don't know how to tell if they need replaced.
I shall try to take a photo and add it later on.
I was mostly careful not to stretch the chain and keep it aligned when riding.

Hi, I measured 12 complete links and they measure 12" exactly.
(My previous measurement (see above) was more than 11 and a half links.)

What do you think now? Alastair

A 9 year, 9,000 mile chain with no measureable wear?.......I think you should write to the Pope and claim it for a miracle.........

[AlastairS]

I know the ruler was not resting on all the 12 links when I measured it so should try again.
Alastair

[AlastairS]

Also, 9000 miles may be an exageration, I have had the bike 9 yrs and I use it occassionalyy, at one time regularly commuting 12 mile round trip twice per week. May be it's only halve that 9000, I really can't say.

[meic]

The chain should also be pulled tight. The CTC tech expert suggested leaning on the pedal with the rear brake applied to measure the top run.
I just hang the chain from a nail and let gravity pull it for me.

[BigG]

The chain should also be pulled tight. The CTC tech expert suggested leaning on the pedal with the rear brake applied to measure the top run.
I just hang the chain from a nail and let gravity pull it for me.

Agreed. If you fix a headless nail to your garage door jamb for this, it is easy to measure off 50" (100 links) below this. In these days of quick-links, testing by hanging your chain on such a nail is quick and simple. I reject my chains at 1/4" elongation (0.5%). This is exactly half a link and measurement by eye is all you need. This method removes all problems with varying chain tension, roller wear the need for accurate instruments. It also costs next to nothing. The initial 50" doesn't even have to be measured; a new chain hung on the nail will indicate the starting point quite accurately enough.

[AlastairS]

Hi, I managed to hang my chain on a nail and this is the result : 52 links = 52 + 5/8ths inches.
I would bee grateful for your comments.Alastair

[cycleruk]

Well that is 1% which is twice the recommendation of Jobst.:-
http://sheldonbrown.com/brandt/chain-care.html

Personally I would fit a new chain and see if you have any problems with skipping or jumping.
If it does jump then chances are the cassette has some worn sprockets.

It is very difficult to determine if a cassette is worn just by looking. Unless of course it's been well and truly overdone. I doubt there is any problems with the chainrings as these usually last a lot longer.

[AlastairS]

Thanks cycleruk, I have ordered a new chain so fingers crossed it will be fine and not jump. Sprockets and chain on visual inspection don't look that bad, but as you suggest, not easy to determine just by looking.
I was wondering , assuming the chain works fine, should the bike feel a bit more responsive?