Well its easy to measure but you I don't believe you can use those measurements to any good. My point is that we are talking about millimeters here. I bet new chains of different brands or even models will have different measurements when we are down to millimeters. The difference between good and worn out chain is so small that even factors such as temperature can make a good chain measure as "worn out" and vice verca. Best indication imo is when you can't ride anymore. Chainrings are heavy duty so they should be fine by then, and you should just have to replace chain and casette. This should be every 5 years or so.

If I did what you suggest my chains would start skipping badly enough that they would pose a safety risk when trying to cross a busy arterial. The commuting forum desperately needs a sticky post titled: do not extrapolate advice from your idiosyncratic retrogrouch experiences.

Using defective or worn out components isn't retrogrouch, its just false economy.
Retrogrouch is preferring things that may be outdated when compared to the latest and greatest achievements of function, but still perform the tasks they are intended to do.

I tend to use 3 chains a year, I like to use a new one (and maybe w/ new cassette) in the summer when it's nice out (historically July but this year since May), when that chain is stretched out, in the fall sometime, I will replace it, and I always hope that chain will make it through the rainy gritty winter but it never happens. And the next chain wears fast too so that it's unpleasant enough that I want a new one for the summer.

Chainsaw oil is a bit too sticky for my taste. Motor oil 20w60 (fully synthetic 0w30 in the very cold winter), or gear oil SAE 90 (same viscosity as 20w60) are good and make sprockets and chain a bit less dirty than chainsaw oil.

I replaced my chain once and found that the sprockets had worn out too. This caused the new chain to skip horribly for a few weeks. Now it's worn to match the sprockets and I'm sure doesn't meet any chain stretch measurements. But you know what? The bike rides fine. If the chain breaks on my way to work, then I'll walk the rest of the way and buy a new chain and cassette.

Somewhere along the line I picked up one of these:

http://www.backcountry.com/images/it...00I/ONECOL.jpg

It's pretty compact. If you also take along a couple of extra links you can save yourself some walking (though you might get by without those).

What value is multi viscosity oil over single grade motor oil for use on a chain which does not need to start on a cold morning, nor will heat up enough while riding to make a difference? Why not use a cheaper single grade oil?

Saw a chain come into the shop the other day. This girl had never changed her chain in the few years she's had her (very expensive mountain) bike. The chain was SO stretched that it wouldn't even fit on the chainring any more. By the time it got to the bottom it wouldn't seat with the gear teeth anymore. How people let their chains get this bad I'm not sure.

I would let it go, many people don't realize bikes need maintenance, but this girl apparently raced her bike as well.

At one point she said something to the effect of "I was wondering why it wasn't shifting very well."

Stop being so ultra-paranoid. If your chain starts skipping then its time to buy a new set, so no it woudn't pose any safety risk what so ever. You would notice it immediately and it would be time to change it. That was my point. Skipping and other obvious signs of wear are the best indicator. Just because you don't agree with my simplistic non-wasteful advice doesn't mean it is wrong. My advice is my advice. When I person asks for advice all that should matter is what you think personally. Take it or leave it so just get off your high horse for a second please.

The reason I use it is because when changing motor oil, there is always some left in a bottle - which is enough to last a long time.

Also, last time I was looking for some oil, SAE90 and 20w60 cost both around 4 $ per litre.

Both 20w60 and SAE90 are the same as far as bicycle chain lubing goes - whichever one can find cheaper, or more convenient.

I think good advice is to use whatever motor oil is on hand, whatever the viscosity, and a good inexpensive source is the residue remaining in the packaging container of whatever oil is used when changing motor oil for any motorized vehicle.

It depends on the season. Winter riding is brutal on chains. During winter time I get 2 months out of my chain on my singlespeed and fixed gear bikes. I never do any special chain maintenance other then few drops of oil every few weeks.

All bicycle chains are 1/2" between pins, and tolerances here are much less than 1mm. No way 2 new chains will differ in 1mm over 12 links.You can easily measure 1.6mm/1/16" with a ruler. Variation due to temperature (dilatation) is so small it's irrelevant.

I've experimented a lot and found that in the summer time, 0w30, even 5w40 are a bit too "thin". For cold winter, 20w60 (or gear oil) is too thick.

I was really bad and went four years on a chain and only oiled it once near the end with canola oil (which actually helped). Once I replaced the cassette and chain the bike felt new again.

I've been much much better with my road bike.

I don't think you can possible "stretch" a chain so much that it breaks.

I've had master links come off if I reused them too much. The only time I've had a chain break is when I tried to reuse a chain that had actually been twisted into a pretzel when the derailleur came off the mount, I straightened the chain, about 400 miles later it actually broke.

I don't even bother carrying tools anymore. I've been riding mostly daily for 12 years and about 35000 miles and I have yet to need a tool apart from a tire lever and a pump (which I still carry) - I don't even need the tire lever on the road bike, the tires just come off easily by hand.

Wrong again. Chains do not stretch. They elongate where the pins intersect the links due to friction. The pins either wear into the links or the pins are worn down by the links. But in either case the chain is not being stretched.

I get about 6500 kilometers (two years of four-season cycling) out of my chain-ring, chain, cassette and pulleys before the drive-train beings to fail at which point I will have the entire drive-train replaced. I use the "chain slipping under seated pedal pressure" guide along with a visual check to see that the ring and cassette are worn down to nothing as an indication that it's time for a replacement. Winter is hard on components. I'd likely get more distance out of the drive-train if I did more than reapply oil. I'll chip away at the gunk when the chain no longer moves freely when backpedaling.

First shop I ever worked in used motor oil.

We had an open quart can with an old paint brush and would just slop it on and wipe it off; never had a problem or a complaint, and that can did last a long time...

Yes I use motor oil mixed with WD-40. A bicycle chain doesn't require any special chain lube, any type of oil will work, even a vegetable oil.

Shop I work at now used to use some branded oil. I just brought half a litre of motor oil, mixed residue from oil changing (I also fix and service motorcycles). Said "here, it's free and works well". We're all using it now. No problems, no complaints. :)

i have no chain checker tool.
i just compare the chain on the bike, with a new chain. side by side.
when shifting goes rad, that is when i think the chain wears out.
just recently i replaced it with a less worn not new chain.
it's good now.

My road bike came with mostly 105 10-speed drivetrain, but I'm not sure if the chain was Shimano 105 10-sp or not. Anyway, after about 2,000 miles it had nearly 1/8" of stretch in 12 links, checked with a metal ruler. I swapped it for a KMC X10L-Ti gold chain and Ultegra 10-sp cassette, and it still has no discernible stretch after over 5K miles.

https://scontent-dfw1-1.xx.fbcdn.net...cd&oe=561415A1

i use the high strength nickel chains like the kmc x8.93. i also lube and clean bicycle chains with made 50-50% blend of pag synthetic oil and mineral spirits. here in florida with the humidity, sand, and salt i have to replace chains about once a year. i have to also keep in stock rear gearing parts too. environment is a major factor here.