I replaced both my cassette and chain in July (2.5 months ago).

For some reason my chain started skipping when I was in the smallest cog in back. I took it to a shop, they could not find anything wrong. They measured the chain and the cogs and said everything looked good, but since it was not working they suggested I replace the cassette and chain again.

So, I bought another cassette and another chain. I just put the cassette on and the bike works great.

Should I put on the new chain too? Or save it for a while?


  • If the old chain has less than 1000 miles or so on it, leave it. Commented Sep 18, 2014 at 22:58
  • 2
    I hope they honored the warranty on that virtually brand new cassette and chain you replaced. Commented Sep 19, 2014 at 0:09

3 Answers 3


If it works great, leave it alone. Measure the chain every few hundred miles and install the new one as soon as the one you have on now is worn beyond spec.

And, when you have a few minutes to spare, read this: http://sheldonbrown.com/chains.htm


I went through a similar exercise this summer. Maybe my experience can be helpful. I have 15 year old Mountain bike with XTR components all around. My 6 year old chain starting to bind in a couple of links so I decided to change it out. I did not buy a Shimano chain but used a KMC 8 speed chain from LBS. I made the mistake of throwing out the old chain. I could have soaked it in degreaser and fixed it. I started skipping immediately, I decided since both the cassette (XTR) and front cranks/rings (XTR) where at 10 years old I might as well change them out. I ordered a new shimano 8 speed cassette and new shimano cranks, plus a new bottom bracket. Since shimano does not make any high end 8 speed stuff I had to settle for what they had. I was not in the mood to purchase used XTR that matched.

(I am not by any means a pro rider and I live where mountain biking offers few challenging places to go, so I don't need XTR, I have become a component snob unfortunately.)

The cassette came in right away. The cranks were back ordered. So I changed out the cassette and it still skipped. I couldn't figure it out until I realized that the front chain rings were skipping. It was imperceptible, even looking at the front chain ring while riding I could not see the chain skipping but I could feel it skipping. So I was nervous when the cranks came in. I installed them, re-tuned everything again. Viola, the bike was back to perfection again. I have ridden about 250 miles on the toughest terrain that Chicago land has to offer and no skipping what so ever. And amazingly enough, now that I have some lower end components I can still ride. The lower end stuff I installed has made no discernable difference in my experience.

So see if your front rings are worn out. If so, change the rings if you can or change the entire unit. Generally you should change the chain depending on riding, about every 500 to 1000 miles. Change the cassette a bit less frequently and change the rings a bit after that. If you use a worn chain it will grind and wear out the cassette and chain rings prematurely.

  • +1 for admitting to component snobbery. It's gets to the best of us.
    – Holloway
    Commented Sep 19, 2014 at 15:22
  • Your higher end stuff is 15 years old based on what I read. Lots of technology has trickled down in that time to the lower groups. Commented Sep 21, 2014 at 2:09

That chain you have will be fine. Chains generally last 1000 or so miles, sometimes more. You should save the new chain to replace this chain currently on your bike when it gets worn out. Not replacing a worn out chain can cost you $$ because you will likely need to replace the cassette and possibly the chainrings

  • I think I'd be fairly disappointed if a chain wore out in 1000 miles.
    – Holloway
    Commented Sep 19, 2014 at 15:21

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