FBinNY 

Here's a better approach that can save you headaches and dough.

1- discard ALL measuring devices.
2- buy 3 chains with reusable connectors
3- rotate the chains every 500 miles or so, keeping the connectors and chains together in married pairs.
4- keep up the rotation system, using the time off the bike to properly clean the chains in mineral spirits, dry, then oil them, storing the "on deck" chain oiled and ready to go in a plastic bag.
5- keep rotating this way until all 3 chains and the sprockets are toast together. Since the chains and sprockets stay well matched in condition, you won't get the skip issue of new chains on worn sprockets.
6- don't obsess or fret, just keep riding until you can't.

**** if you feel that 500 miles is too far rotate more frequently based on whatever level of effort you're willing to put in. (I rotate my chains at 1,000 miles or so).

DrIsotope

Well, you'll never again hear me complain about getting 3-4k out of my 10 speed chains.

davidad

https://jet.com/product/detail/5b516...FQusaQodv3IOLA

It's either this one or a ruler for accuracy.

digibud

Assuming you are not commuting 1 mile each week....odds are the chain, chainrings and cogs are all nicely worn down together. If you replaced the chain it would most likely wreak all sorts of shifting havoc. I ran into that years ago with an old mtn bike that finally stopped shifting well but replacing the chain made it worse as it then had a new chain but worn cogs, hence the "keep replacing the chain regularly" OR just let the entire drivetrain run down the rabbit hole together.

Sirrus Rider

I use this one https://pedros.com/products/tools/gen...-checker-plus/ in conjunction with the park. The Pedro CC measures from three points.

Sirrus Rider

A single commute for me is 32 miles I average 64 to 96 miles a week..

Wilfred Laurier

The Park tool chain checker is a POS. Brand new chains checked with it are indicated as being close to worn out. That chain checker is FIT for the PIT.

PatrickGSR94

Chains on bikes 43 years ago were much more robust than the super-narrow 9-11sp chains used today.

The Park chain tool, and many others, are known for being notoriously inaccurate. They push two rollers apart to get a reading, which means they measure roller wear in addition to pin wear.

I bought a Pedro's chain checker tool, which works exactly like the Shimano tool, for only $18. It measures from the same side of two different pins/rollers for a much more accurate reading. I verified it against a metal ruler on both my worn chain and a brand new chain. On the old chain the tool's pins went in easily. On the new chain the outer left end pin would not fit, as expected.

The bonus of the Pedro's tool is that it also includes a hooked end for use with chainring nuts, and two other hooks on the top of the tool that will hold a chain together while using a chain breaker or similar tool.

Amazon.com : Pedro's Chain Checker Plus : Sports Outdoors : Sports & Outdoors

Wilfred Laurier

I followed a link above to that tool - pretty sweet at less than $20 while the Shimano one with fewer features is $60.

PatrickGSR94

Yep I've already used the chain ring nut wrench a couple of times now, and will be checking my commuter bike chain after it gets a couple thousand more miles on it.

RubeRad

I'm gonna invent a chain-checker-checker tool, so you can check whether your chain-checker has reached end-of life and needs replacing. I'm gonna sell it for $49.99, which will give me a very healthy profit margin, since the chain-checker-checker will be a 13" stretch of brand-new chain.

mconlonx

This.

At the shop, I give customers a choice -- if it reads between 0.75 and 1.00, I tell them that the chain is worn and they might consider replacing it. When it reads over 1, replace, and if they have already replaced one chain, it would be a good idea to replace the cassette, too.

If they are on their second chain for any given cassette, and the chain wear reading is anywhere north of 0.75, I will advise them to keep riding until the drivetrain starts skipping or they begin to get unhappy about the shifting performance, and than any adjustment we do will be best possible given the current state of wear, that they should not expect perfection. Especially heading into the winter -- ride the crappy parts until Spring and then do new drivetrain wear parts.

joejack951

Chains get longer as they wear, though you haven't posted numbers as to how long your chains are when 'worn.' A longer chain won't affect front derailleur performance because it relies almost entirely on the chain's width to function properly. I've never experienced front shifting issues as a result of chain wear and only ever noticed slower rear shifting with a very badly worn chain. Unless your chains are showing 1/8" (3.2mm) of stretch, I doubt you are at that point.