chain wear measurement

[grhm]

Probably a stupid question but...

Everyone always talks about steel rulers and I take this to mean a flat solid piece of steel with very presist measurement. Would I be alright using a measuring tape? You know the type, self retracting 3m tape sold in every DIY store?

I'm assuming that these are accurate enough.


assume a solid steel

 

[ChrisKH]

Probably a stupid question but...

Everyone always talks about steel rulers and I take this to mean a flat solid piece of steel with very presist measurement. Would I be alright using a measuring tape? You know the type, self retracting 3m tape sold in every DIY store?

I'm assuming that these are accurate enough.


assume a solid steel

The problem with these, are the starting points (bit that folds over at the end and stops the tape disappearing up its own arse when you rewind it) which are normally riveted to the end. The rivets have a tendancy to come loose and it can change the measurement.

 

[Dave5N]

They are deliberately loose to allow for whether you are pushing or pulling.

 

[mickle]

How does one tell when ones Park chain wear indicator is worn out and needs replacing?

 

[skwerl]

How does one tell when ones Park chain wear indicator is worn out and needs replacing?

FFS! You use Park chain-wear indicator tool wear indicator tool.

 

[Chris James]

How does one tell when ones Park chain wear indicator is worn out and needs replacing?

You just need to send your £5 tool off each year to a national standards lab to be calibrated???

 

[MartinC]

How does one tell when ones Park chain wear indicator is worn out and needs replacing?

Send them to me with a cheque for £150 and I'll check them for you.

 

[02GF74]

well I got the tool.

very quick and easy to use.

not sure if it has been calibrated by the national standards institute but 2 chains I measure, both of which I reckoned needed replacing with my vernier measurement, I found one within the 0.75 % to 1 % limit. i.e. should be replaced pretty soon and one not even at the 0.75 $ limit, hence in theory has save me some money.

I wholeheartedly recommend this - far easier to measure wear and removes the guessing that vernier method entails.

 

[andrew_s]

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.

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

Roller wear, or wear on the outside of the bushing doesn't matter as it doesn't affect the pitch of the chain.
What matters is wear between the joining pins and inside of the bushing. This does accumulate from one link to the next.

A new chain has about 0.2 - 0.3mm of movement in the chain roller, which is included in what a Park-type tool measures. The roller at one end of the tool is pushed one way, the roller at the other end of the tool is pushed the other way.
Is the roller movement on a new SRAM chain the same as a Shimano chain, a KMC chain or a Taya chain?
Noting that a roller can wear enough to come off entirely, how does the rate of change in roller movement compare with the change of chain pitch?

Park (or Rohloff or whoever) have to make assumptions about roller movement. If you use a chain that doesn't match those assumptions, you could be either discarding a chain that is still OK, or possibly getting chain slip on a new chain despite the tool saying the old was OK (unlikely, as they would be cautious).

If you want ease of use and accuracy, then the only properly designed tool is the Shimano version £27 (at least)

see here for more info (including a 10sp chain wear test)