Hollow Pins

[Mikerb]

I know there has been lots of discussion a bout chains for emtbs but I do not remember anyone commenting on chains that have hollow pins and plates. I ordered a KMC x11 ept chain from a well known supplier but received instead a KMC x11 SL chain. Looking at listings on various sites these chains are twice the price of a x11 ept...BUT are they any good for an eMTB? I guess the main concern may be strength? Anyone used a hollow pin/plate chain?

 

[Mikerb]

Ps....just as a matter of interest I measured the new chain with a Park Tool wear indicator (cc3.2) and it is barely 1mm short of the 0.5% .....cannot imagine it would not stretch by 1mm or more after the first ride!

 

[Mikerb]

Another ps!.....The KMC instruction leaflet that came with chain says the missing link can be re-used a maximum of 3 times but always use a new one on a new chain.

 

[steve_sordy]

Ps....just as a matter of interest I measured the new chain with a Park Tool wear indicator (cc3.2) and it is barely 1mm short of the 0.5% .....cannot imagine it would not stretch by 1mm or more after the first ride!

Is your Park Tool wear indicator worn?

 

[Gary]

Is your Park Tool wear indicator worn?

They're just not very accurate. Even brand new.

 

[Zimmerframe]

Is your Park Tool wear indicator worn?

I've just bought a park tool wear indicator wear indicator tool.

 

[Mikerb]

Haha.....mine is brand new so not worn but cant believe there is not a manufacture tolerance so probably most useful in measuring difference from time to time than relying on absolute accuracy.

 

[Mikerb]

Anyway I fitted the new chain today and it works fine. The original chain is a good spare for the backpack on a long ride and would take 2 minutes to fit with no need for any tools so I am covered if it breaks!!

 

[Gary]

Haha.....mine is brand new so not worn but cant believe there is not a manufacture tolerance so probably most useful in measuring difference from time to time than relying on absolute accuracy.

The inacuracy doesn't come from manufacturing intolerance. it comes from poor design.

Yeah. they're useful tools. I use one at work almost daily. They're simply a quick guide rather than accurate.

 

[steve_sordy]

This is going to sound incredibly anal, but....

Because I have one, I use a vernier caliper gauge. Move it out to 5.7" and measure the chain using the internal jaws. You will get a measurement close to that within +/0.005" on a new chain. That is your base line, so record it.
Every 3 months or 300 miles or so, measure again. The interval will vary by rider, you will soon determine what's right for you.

Compare the measurements to determine by how much the chain has worn. Simples!

Note: I once took a measurement on a chain that was lower than the one taken 3 months previously. "That can't be right!" I checked again and got the exact same reading. I measured a different part of the chain and got another different reading. I measured in eight different places around the chain and it was clear that the wear was varying around the chain. So I took an average and used that, which I have done ever since. This is still quicker and less hassle than removing the chain and measuring 100 links with a steel tape measure. The tape method is the best, no question, because it is accurate enough and averages out variations in wear.

I am still puzzled why a mass produced item made from randomly mixed parts can vary like that, but I accept what is.

 

[gwing]

This is going to sound incredibly anal, but....

Because I have one, I use a vernier caliper gauge. Move it out to 5.7" and measure the chain using the internal jaws. You will get a measurement close to that within +/0.005" on a new chain. That is your base line, so record it.
Every 3 months or 300 miles or so, measure again. The interval will vary by rider, you will soon determine what's right for you.

Compare the measurements to determine by how much the chain has worn. Simples!

Note: I once took a measurement on a chain that was lower than the one taken 3 months previously. "That can't be right!" I checked again and got the exact same reading. I measured a different part of the chain and got another different reading. I measured in eight different places around the chain and it was clear that the wear was varying around the chain. So I took an average and used that, which I have done ever since. This is still quicker and less hassle than removing the chain and measuring 100 links with a steel tape measure. The tape method is the best, no question, because it is accurate enough and averages out variations in wear.

I am still puzzled why a mass produced item made from randomly mixed parts can vary like that, but I accept what is.

Look, this sloppy sort of measurement just won't do.

Do it properly, measure each link in your baseline and then you can check each one properly for stretch irrespective of manufacturing variations. Averages and sampling are so old school ....

 

[Mikerb]

Question is what exactly wears? We call it stretch but I doubt the metal itself stretches so the wear is most likely in the holes of the plates where the pins go through....that would explain ultimate breaking of the chain. Another point of wear could be the diameter of the pins between the linkage plates since that is the point of contact with the sprockets.
If that is the case the only method of measuring both is with tools that are inserted between the pins. ......more anal!

 

[Zimmerframe]

I was just thinking... A di2 bike should be able to calculate chain stretch based on motor to wheel revolutions.(it would need to know what gear you're in) If you reset a parameter with a new chain, it should be able to indicate when your chain needs replacing.

 

[steve_sordy]

Look, this sloppy sort of measurement just won't do.

Do it properly, measure each link in your baseline and then you can check each one properly for stretch irrespective of manufacturing variations. Averages and sampling are so old school ....

I will resolve to try MUCH harder in future!

 

[steve_sordy]

Question is what exactly wears? We call it stretch but I doubt the metal itself stretches so the wear is most likely in the holes of the plates where the pins go through....that would explain ultimate breaking of the chain. Another point of wear could be the diameter of the pins between the linkage plates since that is the point of contact with the sprockets.
If that is the case the only method of measuring both is with tools that are inserted between the pins. ......more anal!

You are correct Mikerb, we call it stretch because that is what it looks like, but of course it isn't stretch. What wears is the pins (rigidly connected to the outer links) rubbing on the bush formed out of the inner links. The pins don't wear in the outer plates because they don't move relative to each other. The bush also supports the roller that runs on the bush. The individual rollers wear of course, but they do not contribute in any significant way to the overall lengthening of the chain.

As each pin wears, each one adds to the overall lengthening of the chain. If 100 x 1/2" links have worn such that the 100 links measure 50.5" then that is 1% "stretch". There are 200 pins and each one has had a radius reduction through wear of half an inch divided by 200. That is 0.0025" or 0.005" in diameter That is quite a lot for the small diameter of a chain pin, so you can see why it is considered scrap at 1% "stretch".

Because the only wear that matters is the wear between the pins and the bush of the inner ink, then you can see why the lubricant has to be in there, not on the outside. However as the chain wears and the pitch extends, the roller starts to slide up and down the tooth face instead of just rolling right in to the root. This rubbing is what wears away the tooth face into a shark's fin profile. This is when some lubricant on the outside will help.

If there are any power transmission engineers out there with a specialism in chain wear then they may take issue with the finer points of what I've written. But that is pretty much on the money.

 

[Zimmerframe]

I'm going to be really sad here .. is there any benefit of taking the chain off every few hundred K's and flipping it inside out and backwards. So the back reverse side of the roller will then wear on the power side instead ? I've probably not explained that very well so you'll have to use your imagination ! So what would be the top of the chain, becomes the bottom of the chain and flipping it round so what would be the trailing side of the roller becomes the forward side of the roller. It's probably not going to do much for the inner wear .. or is it, as the force would be on the opposite side of the pin.

 

[steve_sordy]

I think I see a Nobel prize in the near future for @Zimmerframe

 

[Zimmerframe]

I think I see a Nobel prize in the near future for @Zimmerframe

Probably for crash dynamics, advancement in body armour design & healing techniques.

 

[steve_sordy]

You could always get a job as a crash test dummy! I think that yellow and black would suit you quite well.

 

[Zimmerframe]

You could always get a job as a crash test dummy! I think that yellow and black would suit you quite well.

I thought I was already filling that role rather well You are correct though, I should probably dress correctly for my role - the only problem with the yellow and black is if you run into @Beekeeper on a trail and he's not got his glasses on, before you know it you're netted and stuffed in a tiny slatted box.

 

[Timbo]

I've had a hollow pin chain on mine for over 1500km now, no problems.
I carry a couple of new split links with me in case.

 

[Mikerb]

Thanks@Timbo…….firstly for being the only one that has answered my original question, and second for giving me some confidence my chain will do a few miles! Another facet for @Zimmerframe to ponder for his Nobel Prize could be whether or not the lower swing weight of a hollow pin/plate chain actually REDUCES wear both on the chain and the cassette. ( i'm trying to persuade myself that my purchase mistake will actually turn out to be a revelation!)

 

[Rusty]

Have broken a couple SL chains with my svelte 112 kegs weight and legs like steam pistons. Not a fan of the hollow pins on a MTB chain but did run them on my road bike. If they sent you the wrong chain I would suggest they send the correct one and a self-address bag so you can return the wrong one.