KMC Chains, specs, speeds and wear-resistance

[Ajax Bay]

now more bucks than back then

Don't think "more bucks" stands up. Otherwise agree your jaundiced view of the marketing babble.
https://www.tredz.co.uk/.SRAM-PC-1110-11-Speed-Chain_91920.htm (or bikeparts in EU for you)
https://www.tredz.co.uk/.Shimano-CN-HG40-6-7-8-Speed-116-link-Chain-with-Connecting-Link_26027.htm

 

[PpPete]

Don't think "more bucks" stands up. Otherwise agree your jaundiced view of the marketing babble.
https://www.tredz.co.uk/.SRAM-PC-1110-11-Speed-Chain_91920.htm (or bikeparts in EU for you)
https://www.tredz.co.uk/.Shimano-CN-HG40-6-7-8-Speed-116-link-Chain-with-Connecting-Link_26027.htm

When things are that cheap compared with the rest of the market, I start to worry about their authenticity....

 

[Dogtrousers]

When things are that cheap compared with the rest of the market, I start to worry about their authenticity....

And when things are more expensive compared with the rest of the market I start to worry about getting ripped off ...

Yours, Goldilocks

 

[silva]

Don't think "more bucks" stands up. Otherwise agree your jaundiced view of the marketing babble.
https://www.tredz.co.uk/.SRAM-PC-1110-11-Speed-Chain_91920.htm (or bikeparts in EU for you)
https://www.tredz.co.uk/.Shimano-CN-HG40-6-7-8-Speed-116-link-Chain-with-Connecting-Link_26027.htm

For me it doesn't matter anymore, got fed up by drivetrains quick wear / short life due to all the hassle related to it - I went singlespeed, then fixed gear, then I moved to a motorcycle chain (Regina Urban, a 420 model) which -does- last the time that was "normal" in days back.
And as soon I found out it working, I bought a stock of them for decades, which was before the 2020 economical sabotage, and thus at the "old" price. At the same shop I bought, these are now priced +30%.
I also purchased, earlier, a stock of an "inbetween" chain, the Gusset so-called "Tank" model, which differs being 3/16" wide instead of the motorcycles 1/4", which also proved a longer life, but the motorcycle chain outperformed it, possibly due to the pins a tad thicker (I had toi drill out the hole in a chain tool to 4 mm) and thus bigger mating surface.

I decided to first use up the motorcycle chains because these come with some white grease instead of oil - and showed rust spots even in their original packaging, a kinda glossy butter paper.
Also, some black powderish particles appeared in the grease, alike the chain or grease was contaminated with some particles that oxidized during storage.
The 1st thing I do is wipe off as much as can the grease and dust, then motoroil on it, then ride, then wipe off another time.
The grease is so "sticky"? that a new chain hangs like a zigzag, lord knows why Regina chosed it.
It doesn't lubricate, it doesn't prevent rust, rather the opposite, it exhibits more of a grinding paste to accelerate than to decelerate wear.
That's why I decided to use the motorcycle chains up first.

 

[Yellow Saddle]

1) It's this slowing of the wear rate that causes the tops of the teeth to round off and the chain to skip when you stand on the pedals, if you keep the chain too long. If the wear rate were linear, the time the roller spends at each point up the height of the tooth face would remain constant, and the amount worn from the tooth at each point would also be constant, maintaining the profile of the tooth.

If the chain wears much slower than the tooth even when new you have the converse problem: the base of the tooth becomes undermined before the chain has worn enough to rise further up, and you get 'hooked' teeth. In that case, you're looking for measures that will slow the tooth wear relative to the chain. One way is to buy gears made from harder alloy, another is to share the wear over more teeth by not using the same gear all the time, and the other is by not rotating a set of three chains. A set of three chains just simulates one chain that wears three times slower, and will therefore undermine the base of the tooth even faster.

2) The teeth on my middle chainring get hooked because my riding style leaves the chain on the middle ring most of the time, with all the wear is being taken by just 32 teeth. I've never had to replace a small or large ring, but the middle ones lasted 8000 & 9000 miles (6000 out of a lighter alloy). By comparison, the cassettes aren't hooked even after 19,000 miles because the wear's distributed over a total of 189 teeth. I've never rotated multiple chains. The data I plotted above weren't measured until long after I quit cycling, but in retrospect, had I been making more considered decisions at the time I don't think I would have changed the chains as early as some of those were.

I think your explanation requires some clarification.

In (my insert) Point 1 above: It is not the wear rate that causes wear. It is simply usage. The rate of wear is a function of the rate of usage and load. But the rate itself doesn't cause wear.

Still Point 1: The "stand on the pedals" bit. You have to distinguis between driving and driven sprockets. Then, for driven sprockets you have to distinguish between singlespeed and derailer systems. In the former, the chain enters under tension and in the latter, under slack. These two have a fundemental different mode of wear. However, in neither system, the top of the tooth gets rounded. The top of the cog is contact-free throughout its life.

On a cassette sprocket, the root of the cog (a cog is a tooth - cog rhymes with dog and dogs have teeth) doesn't erode. The trailing face of the cog erodes and the root becomes elongated tangentially (horizontally if the cog points upwards). The effective pitch of the sprocket (and chain) then increases. Now, if you fit a new chain, the mismatch in pitch causes the cog to collide with the incoming chain roller. On a derailer with slack entering at the rear, the new chain simply rides higher on the sprocket (lifting off the root) and remains high as it rolls up onto the sprocket. When it gets to the pressure affected zone where it starts to "feel" the tension in the chain from your leg, it now cannot engage and slips. and skates over the cogs. On a singlespeed where the chain cannot get slack from a spring-loaded derailer. the Cog's ;leading edge collides forcefully with the incoming roller and wears the leading edge. Simultaneously, the trailiing edge also wears. The wear pattern on a singlespeed sprocket looks like a shark's dorsal fin when the shark swims counter-clockwise arund the sprocket. The pattern on a cassette is almost imperceivable. The trained eye can see an elongated root, but no sharp edges, bent-backwards teeth or leading edge wear.

Point 2 above: Cassettes never get hooked for reasons explained above. It has nothing to do with the large distribution (in itself a false notion because all of us wear out just two, maybe three sprokets on a cassette before replacing it). Hooking on a sprocket only happens when the entering chain is under tension and there is no spring-loaded slack available to allow the chain the luxury of riding higher on the sprocket. As is the case on front sprockets and, rear sprockets on singlespeed and internal gear hub bikes.

You are right in that new chains wear faster than old ones. Hertzian contact is to thank for that. With a bit of observational will, you can actually detect this. A new chain often vibrates and hubs for the first 60 or so kms and then goes silent. A new chain is actually under-pitched (shorter). This is due to two reasons: 1) Good manufacturers understand Hertzian contact and 2) a new chain represents a ladder with crooked rungs and a bit of tension quickly straightens things out and makes it a wee bit longer - bringing it to perfect pitch.