RCMoeur 

Yesterday at Recycle Your Bicycle, I was given several chains that had been salvaged off bicycles that couldn't be refurbished, but weren't too rusty and looked like they could be reused on other bikes.

As I usually do, I laid each of them out, applied tension, and measured the distance between pins to assess wear (this time over a 24" distance as I had the luxury of them not being mounted on a bike). I also measured pin width to categorize as singlespeed, 7 speed, 8 speed, etc. As usual, some showed zero measurable wear, some showed minimal wear, and one or two showed a lot of wear.

But then came this chain. The brand mark seems to be "BF", and the BFC-DW part code comes up empty on my Internet searches. The pin width is 7.3 mm, typical for a 7-speed freewheel or cassette.



I measured it, and it came out as less than 24" over 48 links. This is unusual.

So I rechecked my ruler and measured again. Yup, "negative" wear, assuming exactly 1/2" between pin centers. Hadn't seen this before, and it certainly wasn't an oddball 10 mm pitch track chain or anything like that.

Just to be sure, I opened up a brand-new chain, stretched it out next to the BF, matched the links exactly side by side near one end, and compared.

The matched end:



The unmatched end, about 70% of the way down the chain:



Somewhere in the middle:


At 88 links, the mismatch was one half link short or 1/4".

It would have been useful to see what bike this had been mounted on to analyze the wear patterns, but again I got this chain in a pile with a bunch of others and the other wrench probably couldn't recall the bike it came from.

I'm tempted to install this on one of my bikes and see how it rides and shifts under load, given its unusual dimensions. But I wouldn't want to wear out drivetrain components from the opposite direction from wear. Maybe I will anyway.

Has anyone else run into this situation?

Andrew R Stewart 

Did you clean the BF chain before measuring? It only takes a tiny drift off tolerance for a chain's "length" to change over a long stretch. Perhaps this is why a number of chain links are speced for measuring "stretch". Both rust or grime can prevent the rollers/pins from true metal to metal contact.

But the proof in in the pudding. I suggest trying the chain out on a bike to see what real life brings. It sounds like you are fully capable of changing the chain out if the test fails. But do follow up here and let us know. Andy

maddog34

looks like the Rollers are a bit narrower too... hmmm....... here's my best advice... then toss that sucker in the scrap.


ooop.. just spotted the main issue...the relation of the pins to the outer plates... several are misaligned, and that takes up the pin/roller clearance, causing the chain to be effectively "too short"
several of the outer plates are also badly shaped, in their vertical plane...
Chalk it up to lousy Quality control during the plate stamping process.

3alarmer 

.
...roller chain comes in a lot of special variations, because it's used on a lot of machinery besides bicycles.
It comes in various pitches, including some metric pitch chains. I don't know what you have there, but it might have come off something other than a bicycle.


METRIC ROLLER CHAIN SIZE CHART

choddo

you mean like the difference on the lower one of these two?

choddo

Would have to be P slightly less than 12.5mm in that first table I’d have thought?

wheelreason

Best I can tell it's a bunch of InterWeb experts, retro grouches, semi competent DIYers and guys that worked at bike shops in HS or college telling folks in the industry how things go...

Steel Charlie

I can't imagine putting a used chain on anything that I own. The first thing that I do when I bring a bike home is toss the chain, it's junk AFAIK or care. New chains are dirt cheap. They last so long that over their life the water that I consume while I'm on the bike probably costs more.
I suppose that might just be me

RCMoeur 

So... you're saying this chain is an apt metaphor for Bike Forums?

There might be something to that...

RCMoeur 

All you chain snobs people who are suggesting the first move is to send any used chain into the recycle bin: we who toil at co-ops, volunteer orgs, and nonprofits that don't quite have unlimited parts budgets do reuse chains that have some life left in them, for the simple fact we couldn't deliver on our mission if we couldn't. Wholesale chains may be less than $10 each, but it adds up and eats into the tire, tube, and everything else budget. Hence why I gave the chain a once-over prior to classifying it for further service, and discovered its unique properties.

If all of you would like to see these organizations use all-new chains, reach into your pocket and donate to these groups so they have the funds to do so (or use for other worthy purposes). Or donate your time and skills for a few hours per week.

(drags soapbox off stage)

dedhed

I use them on BSOs people bring me to fix who might put on 50 miles a year @ 10 mph with the grandkids. Perfectly adequate for that

maddog34

the un-circled joint shows the pin alignment issue well too. they were pressed in at an angle.... into poorly formed plates.
"Tolerance" in that factory must mean how much garbage they will let out the doors.

3alarmer 

..it depends. What did you use for lubricant ?

maddog34

i am a "Co-Op"... that chain is junk from the factory, and would be properly recycled with the hope that it becomes anything other than a badly made chain.

someone once donated two brand new bell chains to the shop... after a brief inspection, i tossed both into the scrap bucket... They were "Worn out" (too long of pitch) right out of the packages.
Absolute Junk is still junk, no matter the Age.

JoeTBM 

Get up on your soapbox anytime, Yes, we evaluate all chains and replace them as needed. The ones that can be salvaged live another day. BTW we are now getting our chains (6/7/8 speed) wholesale at $2 each plus shipping. We order them in 100 piece lots but if it only a frozen link or two and in within wear spec we try to save it. Every dollar counts in our volunteer shop.

Steel Charlie

Sometimes one man's junk is another man's junk too. Or, in the words of Ferdinand Feghoot, " One man's meat might be another man's poi, son."

Dictatokerr

That's quite a mystery chain! Negative wear is definitely unusual. It might be an interesting experiment to see how it performs on a bike. Keep us posted on the results if you decide to try it out. It could be a rare find or a unique case of wear.

FBinNY 

The illusion of reverse stretch may owe to dried lube filling the gaps. Under load and movement this would get squeezed out allowing the chain to go back to true pitch.

OTOH the beauty of chaindrive is how forgiving of small errors it is.
Keep in mind that a quarter inch over 4 feet only 0.0025 per pin, so not a staggering difference. Short pitch would cause a chain to want to ride lower, or possibly bump tooth points as it winds on or off a sprocket.

The easy test is to wind the chain around a new chainring, and see if the end link can swing out past the next tooth without touching.

If so. consider that you have a chain with a greater wear allowance built it.

RCMoeur 

Science marches on!

This morning, I installed the chain on my "designated test bed" bike (also known as the commutocruiser), which has known-good chainrings and freewheel cogs. I applied maximum practical static tension in the workstand (heavy force on crank, rear brake fully applied) and the chain still measured less than 12" over 24 links. I then rode my local "drivetrain torture test" route, which includes multiple 10+% upgrades, while shifting under load and even when standing on the steepest stretches.

And... it did just fine. No matter how much I tested that chain, no skips, no jumps, no misses, no one left on base. Not bad.

So it looks like I have a chain with unusual characteristics that seems to be fully functional. But just to be sure, I'll keep it on the bike for tomorrow's scheduled ride to the co-op and back for more testing. And then decide its future fate.

maddog34

you have now devoted over an hour to a really lousy chain, with really bad parts, and crooked pins, that's worth less than $5.
will you still be pleased with your decision when it breaks while on a customer's bike?
sometimes, being "thrifty" is just an excuse for being dumb.

3alarmer 

...the reason I change out chains on my own bicycles (that I overhaul and repair), is that chain rings, freewheels, and cassette cogs are usually more expensive components to replace. So it might not be that way at your co-op. Conceivably you have an infinite supply of cogs and chainwheels in various iterations. I have bucket of chainrings, but my supply is not infinite, and a ten dollar KMC chain is a worthwhile investment for me. I rationalize the expense by telling myself it's the cheapest way to go, in the longer run.

If the chains I take off are within usable spec, I save them up and give them to the co-op here. But a lot of them get tossed.

KerryIrons

Richard, I think the most likely explanation has been given: poor quality control at the factory. I've never heard of the BF chain brand, but I'm guessing it's not a main line brand/company. And if their chains are a bit off, given the market they think they are selling into, price will dominate performance every time. I'd bet this chain will wear fast, so it will come into actual half-inch pitch pretty quickly

Iride01 

Is it certain that this is a bicycle chain at all? Might just be a chain some previous owner had access too and seemed like it'd work to them. But I haven't read all the thread, so I might have missed something more relevant.

FBinNY 

99% certain it's a bike chain. Looks to be a copy of an old Shimano design.

The bulged outer plate is key because there's no reason to do that except for use with derailleurs.

rosefarts

I have neither the skill or equipment to do so, but I’ve always thought it would be cool to use old chain, and various other worn steel parts to make a knife.

Ive seen enough episodes of forged in fire that if I had an anvil and a forge, I’d give it hell and see what happens.

Still a waste of time on something with no value, but I might end up with a cool letter opener from the experience.