I still claim that a 1% stretch (1/8 inch in 12 inches) is the best criterion for chain wear. By that time the chain isn't engaging the sprockets properly and most of the load is being carried by 1 or 2 teeth instead of the whole engaged length. By the time you notice significant hopping you've already started doing a number on the cassette.

Also, the lubricating properties of the best synthetic oils greatly exceed any bicycle chain lube or they wouldn't use it in the most abused engines in the world!

You want to be careful about assuming that what's good for engines is good for your bike.

Lubricating a chain and lubricating an engine are two entirely different things, Engine oil flows and it's filtered; chain lube stays in one place and simply accumulates dirt and metal dust from wear. Engine oil is forced through under pressure; chain lube needs to stick in one place.  Engine lubricants operate over temperature extremes; chain lube runs at ambient temperatures. Bicycle chains operate in dirt; engines are clean (relatively). Engine parts operate a high speed; bike chains move slowly, so the lubricant film requirements are completely different.  Engine lubricants have additive packages to address conditions that don't exist in bicycles; the biggest need for chain lubricants is to keep the chain clean.

This thread is amazing!]:)

It really is.

CPW

The issue is not about being terse or not. My last comment was simply in regards to all prior posts about the costs of top quality chains versus chain rings, cassettes, smoothness of chain travel, noise, pedal efficiency, frequency of chain purchase and the common conclusion repeated on this thread that everyone agrees with about cleaning and lubing being the reasons for long chain life. What is amazing about this thread is that posts are being made without reading all of the prior posts and causing opinions and facts to get repeated.  Also, the issue of chain replacement frequency seems to be a sensitive topic considering the simplicity of the original question that started the thread.

My own experiences have proven to me that the changing of my chain when it hopped in the tallest gear was sufficient and when my bike needs the chain rings and cassettes changed I will fix it when it's broken. My research on prices of Ultegra cassettes and chain rings on my main bike was about the same as the DuraAce chain that I use. My bike now has 18+K total miles and is on its second chain without the need for a new cassette or chain rings. It's quiet, smooth and fast. That is obviously due to many factors in how I ride but most important being cleaning and lubing of the chain after every ride. I told my story as it is true and if people choose to do otherwise such as purchase chains more frequently because they wish to clean and lube less often or simply want to purchase chains because they believe other than what I experienced, so be it.

I posted earlier my less than empirical "poll" of riders here in the Detroit area for their take on chain changes.  In addition to the postings here at Active we see a very wide range of behaviours with changes from 1,000 miles all the way to 40,000!   That said, the riders who were most diligent were often those who prematurely wore out a cassette or chain rings because they put off swapping chains and they did not want to have to replace those costly items too frequently.  Racers can't afford a skip when attacking a hill as it might cause them to crash, which sadly enough did occur on one of our fast training rides this summer causing a catastrophic crash resulting in four going to the hospital, one rider having both clavicles broken and severe brain injury requiring surgery.  He is home after a 6 week hospital stay but it will be a while before we know about his progress.  So, in the context of being prudent, it seems that keeping that chain clean, not crossing over the gears when riding, and other elements, say only riding flats and weighing under 140 lbs!!!! (not me since junior high) puts less stress on the chain.  Using the measuring tool to assess the stretch seems to be the best way to go. You can use a ruler as mentioned by another contributor or just ride to a shop and ask to borrow theirs. 

Change the chain as you would the oil in your car!  Keep riding, have fun, and buy more bikes!

EJ

I love that story. Wish you lived next door!  I love to ride and the more I ride the more I want to ride and I even like to clean the bike on those nice summer days after I've already ridden and relax with some music on.  I just wish I was a more confident mechanic. 

Best,

EJ

Hi!

I figured you were from California.  I checked on the internet and that ride looks to be a blast as you get to share the road with TEN THOUSAND of your closest friends.  Do folks turn around and ride back later that day or the next day as well?

EJ