Chain measurement issues here

In the past I have tried in vain to check my chain wear with wood rulers and metal tape measures but my poor old eyes and crap knees make it difficult for me to get close enough or see well enough to do me much good.

I finally broke down and purchased a chain measurement tool and even got a lesson from the LBS in its proper use. https://www.bikeparts.com/search_resu...p?ID=BPC331423

I also have recently acquired 15" a metal ruler that I can actually see well enough to measure the chain with.

Here's my issue....the tool shows me different results than the ruler does and to varying degrees depending on the bike. On my EZ Sport the tool says the chain is at 100% stretch while the ruler measures the pins at 0% stretch. On my Tour Easy the tool says 60% stretched and the ruler 0% stretch and my Volae the tool says 50% stretched and the ruler 0% stretch.

What am I missing? Are the rollers wearing on these chains showing stretch with the tool yet the holes in the side plates and the pins aren't worn yet giving me passing results with the ruler? Does any of this make sense? I believe that I'm tensioning the chain the same regardless of my measuring method so I'm confused by the variability.

I would go with the ruler and never replace a chain again!

Seriously though I have no clue because it seems that maybe you are measuring wrong with the ruler? Not sure though. Does seem weird.

Lenny,

Not sure whats going on here but this is what I would do. Measure the tool with the ruler and see what you get.
I suspect the tool is correct and there is too much variability in your use of the ruler. Since both the tool and the ruler measure cumulative stretch across multiple links you will see both link stretch and roller wear.

Three is a process called a gauge r&r used to determine the variability in a measurement system but baring the full use of statistical methods I would do as I described above.

ruler is measuring pin to pin external to the chain links?
tool is measuring inside the link -- roller to roller/pin to pin? I would think if the rollers are worn it will be wider between pins as there is less roller there due to wear. that's how I see this happening. I use the tool as I don't have a metal ruler and wooden ones are not very accurate. it's all relative anyway.

Since the LBS showed you how to use the tool, I would trust the tool. Also, try the tool on a brand new bike (take it with you to a bike shop). See what you get there.

Because your only looking at a 1/16" difference, you need to be very precise in measuring, it's easy with a chain on a bike to be out 1/16", which is the difference between being ready to be replaced and still good. The tool is usually precision made, and because the LBS has shown you how to use i properly,I would trust the tool.

If your tool is like mine, it provides some tension on the links which I whink would accentuate any stretch.

Trust your tool. If you don't, no one will.

^^^ This.

Just ask someone who has just replaced a cassette, RD pulley wheels, and a middle chainring because he used, but ignored his chain checker. Chains are cheaper.

I know that since you have to string several together, chains aren't as cheap for bents, so it throws the whole chains are cheaper than gears equation into a tizzy. But you also use eight or nine-speed chains which are a whole lot cheaper than 10-speed ones. You can buy three 8-speed chains for what one of my 10-speed chains costs.

No tension from this tool, it's just a "drop in" style checker. I provide tension myself. Since I provide the tension for both measuring methods I almost think that my technique may not be the culprit. I may take take a bike, the checker and the ruler to the LBS for an explaination of what's going on.

Yes, financial justification is bass-ackwards on most of my machines. I do have one 9-spd ( the Volae)with a high end cluster, the rest are 8-spds and the chains are the expensive part of the package. I do have two 14' chains on their way to my house and I'll install and closely monitor their wear.

No matter how far I've pushed off replacing chains in the past, I've yet to destroy any rings.

Run a chain till it is worn out and use it for another couple of hundred miles- Then you find out how much cassette and Chain ring wear you have when you fit a new chain.

God help us if this post ever gets taken out of context.

OK, first some definitions: A bike chain consists of rollers held between inside links attached by rivets to outside links. So, chain measurement tools assume that all rollers are the same diameter. They also assume that the tool will be placed straight in the chain (perfectly parallel to the links). So problems in measurement could occur if the chain rollers are slightly smaller than they should be, or if the measurement tool is placed somewhat at an angle. There might also be some play within the roller. If there is the remotest possibiity of any of this, then your measurement will be out. I like measuring the top of the chain with some pressure on the pedals so the chain is taut, and with the tool pushed all the way against one side of the chain, or just measuring between two links with a ruler, but measuring the leftmost side of one rivet against the leftmost side of the other rivet 12 inches or away (not center of rivet to center, which is not as accurate because the center of the rivet is not usually marked). (Note that even if you live in a metric country, you still need to use a ruler graduated in Imperial inches because bicycle chains are all pitched at 1/2-inch.) And all pedals have a 9/16-inch bore. Go figure.

Luis

Thanks for the technique advice Luis. These are the little things that make a big difference.

My new chains arrived today and you can be sure when my free time finally arrives on Tuesday that before I replace either of the chains, I'll remeasure all three chains I'm currently using while trying my best to utilize the techniques you described.

Thanks to all who helped.

I'll let you know how I make out.

A little additional info.....

I pulled the chain off of the EZ Sport today. The tool still indicates 100% wear in most places on the chain though the metal ruler indicates no stretch at all.

I hung the chain from a nail up in the garage rafters and hung the new chain right next to it. I find this is the easiest method for me to quickly size the new chain. With a bit of tension on each chain it becomes readily aparent where to break the new chain. Son of a gun!! The links on both chains line up perfectly from top to bottom. My tool indicates no wear on the new chain. I definately have wear evidence on my cassette, to the point wear I'm ordering a new one tomorrow from my favotite LBS.

My theory: The surface of the rollers have worn down before the holes in the side plates and the pins wore down. My tool picked up on the roller wear whereas the ruler method has no way of checking this type of wear. I intend to verify the validity of this theory at the LBS tomorrow.

I have this one from Park. Works very well https://www.parktool.com/products/det...at=5&item=CC-3