Bicycle Mechanics - Chain stretched?

I was at the LBS today asking about "chain suck" and the mechanic there said he would take at look at the drivetrain to see what was wrong. He spun it a few times, shifted, and then measured the chain with a foot-long ruler. He said that the problem was due to the fact that the chain was "stretched" beyond its service limits ... he said that each pivot link on the chain is 1/2" apart, and if you measure with a 12" ruler, the start and end of the ruler will land on a pivot link. Mine was a little farther, like about 1/4".

Is it true that I need a new chain?

Yes

worn , rather than stretched

Man, that chain should've been tossed years ago!! At this point, you'll also need to replace your cassette/freewheel, and, quite likely, your chainrings, too. It's going to cost you anywhere from $45-$120, depending on the quality of components you buy. A regular changing of a simple $10-$20 chain would've prevented all this...

The general rule is to replace chain when it has "stretched" 1/16 inch over 12 inner-outer link pairs (25 pivots center to center, I'd guess). 1/8 inch if you're a slacker. Dude, you're in a whole new category. ;)

Originally posted by roadbuzz
The general rule is to replace chain when it has "stretched" 1/16 inch over 12 inner-outer link pairs (25 pivots center to center, I'd guess). 1/8 inch if you're a slacker. Dude, you're in a whole new category. ;)

Agreed. See sheldonbrown.com

Thanks for the insight! This is an old bike, and I got it used for a pretty good price. It rides very well, except that it's riding with a 8-speed cassette and a 7-speed shifter (so it doesn't shift very well). I haven't ridden it on the trail so I haven't really tested the chain condition.

I will probably get some new drivetrain components then. A new chain and a 9-speed cassette (with 27-speed shifters).

And what's a chainring? :confused:

The chainrings are at the other end - on the cranks. <shakes head in bemusement> You'll get it. Go here www.sheldonbrown.com , you'll learn a LOT.

If I swap the chainrings, would I need new cranks as well?

Depends.....

Replaced the chain, and the chainrings+rear cogs look ok. Here's a pic. I love the Park Tool chain breaker. :D

All that's left is to get some mud on it.