Originally Posted by
cxwrench
Here we go again...no, they do not stretch on a bicycle. This has been discussed thousands of times. If you think they do, on a bicycle, prove it. And not w/ a chart. Physical proof.
Well, if you'll take anecdotal evidence...
1. Replaced the rear shift cable on my 105-5700 Cannondale early last year. Perfectly adjusted when installed, two rides later was shifting off-center and had to re-adjust. Haven't touched it since.
2. Built a vintage Cramerotti late last year, with Campagnolo mech and Jagwire cables. Perfectly adjusted both front and rear shift cables. Had to adjust the rear one ride later, the front two rides later. No adjustments since (but to be fair I did hang it on the wall after riding it for a month or so).
3. Built a new carbon gravel bike this fall. Chinese frame with 105-7000 series groupo and again Jagwire cables (what can I say, Shimano only offers black...). Rear hasn't needed adjusting yet, front has been adjusted once and needs one more tweak. While these cables are mostly internal, I ran housings full length for better cable protection overall on gravel.
I may accept that it's not the cable that's stretching, but there must be a mechanism that's letting the cable appear to slacken not long after it's installed. What do you say is that mechanism, if it isn't the cable stretching?