Which chain wear measuring tool?

[dodgy]

I'm astonished that the Shimano one costs £53.99!
http://www.chainreactioncycles.com/Models.aspx?ModelID=23263

I use the much cheaper Park one, when it fails the 0.75% test, I start using a steel ruler because of the 'roller slop' issue.

 

[Davidc]

I used to do it properly with a steel rule and pin to pin. Then I bought a Park Tools one and checked that it gave the same results as the ruler. It did to within the accuracy I could measure to, provided it was used with the chain in tension.

The Park one and others like it may not measure the wear properly but they're quite adequate for the when to replace +/_ 100 miles decision I need.

Very likely numbnuts spoke is perfectly adequate too.

Who needs an expensive tool. A chain for most of us is between £10 and £20, a cassette is about the same if we get it wrong occasionally.