25 Responses to “How To Calculate Chain Length”

1. Paul on January 24th, 2008 9:27 pm
   

   Alex,
   Very good and simple. I have replaced several chains and did not know there was such a technique. I always did it by “feel”.

   You may want to also explain how to determine when a chain needs replacing. Most folks rarely do this.

   Status of this Request
2. Xtreme on February 19th, 2008 5:27 pm
   

   Thanks for the info sir. As stated it is important not to run the chain to the rear derailleur on the process. I just wonder if the measured length you’ve mentioned will compensate once the chain is rolled to the rear derailleur? Will I be able to shift to big gear front and big gear rear with this length? Thanks!
3. Alex on February 19th, 2008 6:20 pm
   

   Hi Xtreme,

   Yes, this length should be sufficient to allow a big-big gear combination. It’s also a good idea to shift your derailleur into the small-small combination, and then check to see if the rear derailleur pulleys are horizontal (the chain should be hanging about one inch below the guide pulley).

   As all derailleur/gear combinations are different, it’s a good idea to test both methods to find the optimal length for your bike.
4. Dave on March 17th, 2008 1:14 pm
   

   After watching the video, you appear to be pointing to the wrong place to break the link. Breaking it where you are pointing would result in both ends having outer links. I think you should point to the next (longer) inner link.
5. Alex on March 17th, 2008 1:20 pm
   

   Hi Dave, after reviewing the video I can see how it might look that way, but the inner link is there, sitting on the chainring (it blends in a little).
6. BPS on July 11th, 2008 2:10 pm
   

   yeah he pointed to the okay spot:)
7. John on July 18th, 2008 2:54 pm
   

   Thanks for all your info on bike repair. When I replace my chain, how can I tell if the gears are still in good condition or if they need to be replaced with the chain.
8. Alex on July 18th, 2008 10:09 pm
   

   Your front gears should be ok as it takes a lot longer for them to wear out. However, you’ll likely have to replace at least the smallest rear sprockets, and nowadays most sprockets come as a single unit. To test it, go for a ride with the new chain installed, shift into the smallest rear sprocket on a hill, and pedal hard. If the chain slips under that much pressure you’ll know the rear sprockets are worn.

   ** Be careful so you don’t hurt yourself if it slips **
9. mb on September 4th, 2008 6:39 am
   

   Is this the method that would be used to measure the chain for a child’s 1-speed bike? My neighbor’s boy has a new bike that he can’t ride much because the chain is always falling off, and I was wondering if this was because the chain is too long. I’d like to fix it for him if I can.
10. Alex on September 4th, 2008 7:57 am
    

    No, this method won’t work for a single-speed chain. To correct your neighbor’s loose chain, loosen the rear wheel and pull it back until the chain is tight (leave a tiny bit of slack) and then tighten the wheel again.
11. Lawrence on October 13th, 2008 3:21 pm
    

    I’m in the process of reconditioning my bike. Your tutorial had helped me save a lot of time and labor money. Since I’m at it also, I’m also upgrading some parts of my drivetrain. My question is I have what it seems to be a long cage derailleur on my current bike setup. I ordered a mid cage. Do I still use the same technique to calculate my chain length. My gear combination is 11-30 rear and 22-32-42 front. Thanks for the info.
12. Alex on October 14th, 2008 12:26 pm
    

    Yes, you can still use this same technique!
13. Steve Sloat on October 27th, 2008 5:59 pm
    

    I busted one link of my chain, and ended up losing the little pin in the link. I opted to use the old chain off my old bike. It was too long, so I used the method here and worked great. Of course, I had to degrease the old chain something awful, but it worked brilliantly.

    My question is if I didn’t have the extra chain, could I get away with taking a complete link out of the chain, and limping back home on a shortened chain? What consequences would there be by using a shortened chain?

    I’m driving a Specialized Hardrock Sport with 24 speeds.

    Thanks
14. Alex on October 28th, 2008 7:29 pm
    

    A shorter length chain is ok in a pinch if you stay out of the bigger sprocket combinations. Run through the gears and you’ll see the rear derialleur start to point forward, which is not normal. Stay out of gear combinations that make it do that until you get home and you’ll be ok!
15. Alex on October 29th, 2008 7:32 pm
    

    @Paul: Here is a video that shows how to check your chain wear.
16. Gary on November 1st, 2008 1:08 pm
    

    I have always used this method to size up my chains. It’s a great method. However, I plan to get a 12-27t cassette in the future. I currently have 12-25t. Would it work if I just added 2 extra links to accomodate the extra 2 teeth? I don’t have a 27t cassette at the moment to try it on.
17. Alex on November 2nd, 2008 1:19 pm
    

    It should work. Install the new chain and check the measurement again once the new cassette is installed.
18. Fred on December 23rd, 2008 5:00 pm
    

    Hello there Alex!
    Just to make sure:
    If I used a quick release chin link, the QR link MUST be the last OUTER link that you pointed to, correct?
    So I assume I should cut 1 link closer to the chainring than the one you pointed to, and simply apply the QR link as the last OUTER link?

    Thanks! =]
19. Alex on December 24th, 2008 2:41 pm
    

    Yes, you can consider the quick release link as a regular link when making the calculation!
20. Ian on January 2nd, 2009 5:52 pm
    

    Hello Alex ,

    I need to change my chain and here is the question.
    If I count the other chainlink on my present chain there is 54 outer-link. With your method it would give me 53 outer-link. Will it change something?

    Thank’s

    Ian
21. Alex on January 4th, 2009 1:12 pm
    

    Hi Ian, if you are simply replacing an old chain the best method would be to make the new chain exactly the same length as the old chain. The video above is meant to show how to measure a new chain when you have no old chain to use as a reference.
22. Simon H on January 5th, 2009 6:47 am
    

    Hi Alex,

    Would it be possible to use the existing chain, once removed from the bike, to calculate the length required for the new chain, after allowing for the slight stretching of the old chain?

    Regards,

    Simon

    P.S. Your tutorials are excellent and easy to follow. Thank you.
23. Alex on January 6th, 2009 1:16 pm
    

    Thanks Simon… sure, you can use the old chain to measure the new one. It’s actually better than using the method above. The video shows how to measure the chain if you don’t have the old one to go off. However, this might be a problem if your old chain wasn’t installed correctly to begin with…
24. Ian on January 6th, 2009 6:03 pm
    

    Thank’s Alex,

    I decided to try your method instead of counting my old chain links. My first impression is that when I’m in 53-25 the derailler is a bit more stretch. But we all know that we should ryde in 53-25 so I’m ok with that. For the rest it seem to work good.
    I also think that using a shorter chain shoul prevent from the early damage to the cassette and chainring.

    Thank’ s again

    Ian

    PS: Your tutorials are excellent. Keep your good work!
25. Jon on February 27th, 2009 10:06 pm
    

    Hi Alex!

    Thanks for all the great tutorials. I recently changed my cassette (not the same size as the old one) and so need to put on a new, longer chain. Going by this method that you illustrate, I can either have 1/2 a link overlapping or 1-1/2 links overlapping. I’m using a long cage derailleur, 11-32 cassette, 22-32-42 chainrings. Which would you recommend?

    Thanks!

Comments are temporarily closed. If you have bicycle repair questions please visit the forums