chain wear measurement

[02GF74]

I bought a lovely KMC gold chain off the bay and dithering whether to replace chain or not.

The bike chains are 1/2 inch which means that for 10 links, a new chain should measure 12.7 mm.

I measured it to be less than that, don't recall figure but could be 126.2 mm. Strange. I would have expected it to be 127 mm.

I am guessing that the chain is slightly short to exten life, i.e. it wears a bit so becomes the true 1/2 inch legnth then can wear a bit more past that.

I got numbers off the web a while back the length of 10 links on a new chain and the 1 % increase whcih is when the chin should be replaced, I cannot recall the first numebr but the latter is 127.6.

I have been using the 127.6 mm for quite a few years and can get at least 3 chains on same cassette prior to having to replace cassette.

Anyone wishes to comment on these numbers?

Thinking of getting one of these but if my method is osund, is it worht the £ 5?

The tool is far easier to use as it eliminated any guess work.

I don't suppose anyone has come acros a dimensioned drawing for this type of tool?


Over to you knowledgeable peeps.

 

[jimboalee]

Contrary to what we might read, a bicycle chain has a pitch of 1".

That is one inner link and two outer plates, each of 0.5 inches between the rivets.

10 links are 10". If the 10 links measure 10.1" on a standard engineering steel rule using the 10ths scale, the chain is worn.

 

[ChrisKH]

As you say, the tool reduces the guesswork and engineering tolerances, etc. I have a Park one the same which has been invaluable in deciding whether the chain needs replacing. And then you have it for life.

 

[Over The Hill]

It will probably be a true length after a few miles use as it must just bed in a bit.

Better to stick with it in inches and measure over 20 links. My chain is so worn it is about a quarter inch over length now. Must get round to replacing it. I cant see the point in getting a tool that simply tells you the length beteween two points on a chain. I have a tool called a tape measure that does that.

 

[HLaB]

As you say, the tool reduces the guesswork and engineering tolerances, etc. I have a Park one the same which has been invaluable in deciding whether the chain needs replacing. And then you have it for life.

+1 Its quick and easier too.

 

[andrew_s]

+1 Its quick and easier too.

Quicker and easier and less accurate than a ruler.

What tools like the Park one measure is the length of 3 links (or so) plus the amount of movement of a roller.
This last is variable between different types of chain. Some will show as half way to worn even when new.

 

[Big John]

I've got a metal 12" ruler - it's EXACTLY 12" from end to end i.e. no little additional bits on each end. If you put the end of the ruler half way along one of the rivets then you should be exactly halfway along a rivet further along the chain. If it's not precisiely on half a rivet then the chain's worn. Cheaper than a Park tool but I'm not knocking Park as I think their tools are terrific - expensive but terrific.

 

[Dave5N]

I've got the Park thing but Big John is right - a rule is easier.

 

[HLaB]

Quicker and easier and less accurate than a ruler.

Probably is for you but I'd find the faff of a ruler more complicated and time consuming; if it was that inaccurate Park wouldn't put their name to it.

 

[Dave5N]

Quicker and easier and less accurate than a ruler.

What tools like the Park one measure is the length of 3 links (or so) plus the amount of movement of a roller.
This last is variable between different types of chain. Some will show as half way to worn even when new.

Err - that's what you're looking for. Chains don't stretch. The bushes (or bushlessnesses) and rollers wear.

 

[threefingerjoe]

The Park chain measuring tool...or whoever's is a "Go, No-Go Gauge". True, it won't give you a good measurement, but, in most cases, you don't need to know the length of so many links. You just want to know if the chain is worn. These gauges tell you that.

 

[jimboalee]

The quickest way to see a worn chain is to look between the valley of the chainring teeth and the chain. If you can see daylight at ANY meshing link, the chain is worn.

 

[02GF74]

well, I forked out for the £ 5 tool. I use a vernier caliper but it is quite hard to get the centre of edge of a rivet lined up, and we are talking fractions of a mm that could make a difference. At least this will save me time.

Probably won't save me money as I discover I need to replace chanins!!!

I'll let you know how I get on with it vs vernier caliper method.

 

[Chris James]

I've got a metal 12" ruler - it's EXACTLY 12" from end to end i.e. no little additional bits on each end. If you put the end of the ruler half way along one of the rivets then you should be exactly halfway along a rivet further along the chain. If it's not precisiely on half a rivet then the chain's worn. Cheaper than a Park tool but I'm not knocking Park as I think their tools are terrific - expensive but terrific.

If your ruler is exactly 12" with no gradations beyond that, then you are correct that any extension is wear. But you are not able to measure the wear due to your ruler being too short!

It is for this reason that Chris Juden (I think) recommends looking at 10 inches, rather than 12.

I have a chain wear tool which I find easier than trying to tension the chain via the pedal with one hand and line up the rulers markings with the rivets with the other. I think the tool cost about £7, which seems reasonable enough to me given the price of chains, cassettes and chain rings and the fact that the tool will last forever.

Both methods are fine though, I just find the checker tool easier. In the same vein, for years I used to take off my pedals using a combination of allen keys / adjustable spanner / hammer and a lot of sweating. Using a proper pedal spanner is a lot easier, and the pedal spanner was (I think) more expensive than a chain checker and used less frequently.

 

[skwerl]

Contrary to what we might read, a bicycle chain has a pitch of 1".

Not sure I believe that. A link is 1" but pitch is the distance between two sprocket teeth, (ie 1/2" or half of one chain link). Just the same as the pitch of a screw thread being the distance between two thread peaks