Had a DA CN7901 chain since Aug 2013. It came with the (new) bike which is full DA7900. I decided to order a new CN7901 chain as a spare/replacement as I couldn't get it be silent in 15th gear. I noticed the original chain had a fair bit of stretch in it in comparison to the new one.

Should a chain not last a bit longer than 2-3k miles? I do a lot of hill climbing and powered gear changes are sometimes needed.. is this why the chains stretched?

To avoid premature wear follow this:

https://sheldonbrown.com/chainclean.html

2-3 k miles is a bit short but not terribly so. Riding in wet gritty conditions can considerably shorten chain life. Frequent lubing with good wet lube can improve longevity. Good cleaning helps, but poor cleaning can reduce life over not cleaning at all. I typically get 3-5 k miles dry miles and replace chains when they exceed 1/32" elongation over 12" (the usual rule is 1/16").

Depends on your road conditions and how much grit you get in the chain; how often you clean and lube the chain; and just in general maintenance of your entire drivetrain to eliminate wear. No variable or secret here.

Excuse my French but - **** that , £26 bought me a new chain.

I've been using Fenwick road lube which is a dry compound. I did clean the (old) chain but not scrub it. The stretch over 110 (ish links) was about 4-5mm?

Use the search function.

The correct answer is "it depends."

If you really abuse your bike and never oil the chain, I bet it could be worn in 2K miles easily.

If you keep it clean and oil it every few hundred miles, it should last a bit longer.

Everyone is different but i get 4-5,000 miles from a chain.

Back in the day of 5 or 6 speed chains, you could easily get 15000 miles out of one, but the newer skinny chains wear much faster.

I don't ride in any particular bad area but after every two rides I clean my chain with a chain scrubber and my cassette as well as my chain rings and rear derailleur cogs to be free as much from road debris as possible. Am I OCD???? Why sure I am! But my chains and cassettes last............plus I get mental reprieve by getting alone drinking a nice cold Stella or Sam Adams while partaking in a fine stogie and clean my bike! Therapeutic you might say!

Holy crap...

There is no way in hell I'm going through that much work to clean a chain. If a chain wears out, I'll just replace the thing before I go through that much effort taking one apart. I bought clearance 10sp Ultegra chains for $24 from PBK and chucked them in storage.

I do need to get a chain stretch "go/no-go" gauge though...

I usually go through a chain in a year.

IMO, dry lubes can be OK, but need to be applied often as when they get pushed out of where they're needed (between pins and bushings) they don't flow back in. That's why they're wet when you apply them, to flow where needed. If you hear squeaking, you've already gone far too long.

Proper cleaning of the chain (removing debris from inside the pins, bushings and rollers) is a bit tedious, and may not be worth it considering the effort involved, the amount it helps, and the cost of a new chain if you shop wisely. Keep it well lubed, wipe it down for cosmetic gratification, and replace when needed.

Whoosh!!!

Took me a while, though.

I started reading that and thought it was a joke. Double and triple checked the page - sheldonbrown - no joke. I think I would have to be completely unemployed for that time to be worth it. No no, even then I'd do better spending that time looking for work.

Aaron, it is a joke.

The above bold/italic statements pretty much answer every question ever asked on this forum.

Honestly though, I'd say that there are way to many variables to give a hard mileage number. Keep it clean and keep it lubed. Nothing more you can do. The conditions you ride in may or may not be something you can control, so just clean, lube, and check for wear regularly. You'll find out what is normal mileage for your chains soon enough.

LOL! Never seen that before. I've been doing it all wrong!

real cyclists don't joke around

I can’t trust this, coming from a cyclist.

Oh. I feel dumb haha

Oh darn, now I have to put it back together.

You only figured this out when you tried to order the cleaning kit, amiright?

Thats funny...I didn't read it. I scrolled through the pictures and thought to myself "these guys are seriously nuts!!!"

LOL...now I'm going to have to go back and actually read it...

Even in death, Sheldon can troll noobs like none other. I miss the guy.

So who's riding 11 speed and what kind of mileage are you getting out of your chains?