What's your method to determine chain length

[Veloo]

Lots of methods shown on the web but what's your MO for trimming a new chain to proper length?

[Don49]

Been discussed many times. See here: http://forums.thepaceline.net/search.php?searchid=1576404

[KidWok]

Make sure it is long enough to clears big-big. Make sure there is still chain tension in small-small.

Tai

[Louis]

Tai, if while cycling in Ireland someone were to ask you how to get to Tipperary, I assume you would tell them to simply pedal until they got there? ;)

http://www.shelleymunro.com/blog/wp-content/uploads/Tipperary-Ireland.jpg

[Germany_chris]

Big-Big add a link.

[Tony T]

I use the Equation method from: http://www.parktool.com/blog/repair-help/chain-length-sizing

[Jonathan]

I just make it the same length as the chain I'm replacing. As that, for me, means removing four links, I get a free chain after every 27 I buy. :)

[Tony T]

Of course that only works once you determine that the existing chain length is correct. :)

[Rob1519]

I have used this calculator and several other methods and have found them to generate essentially the same results

http://www.machinehead-software.co.uk/bike/chain_length/chain_length_calculator.html

[Formulasaab]

Make sure it is long enough to clears big-big. Make sure there is still chain tension in small-small.

Tai

This is my method too. :cool:
I'll add that if both situations aren't possible, I would make sure it can do big-big and give up little-little. My thinking here is that you can get "locked" in big-big if the chain is too short and may damage something, whereas having a floppy chain in little-little will do no more than make that "you dummy" noise while you pedal. :no:

[harlond]

Trial and error.

[TimD]

I'd probably use a tape measure.

[gmcampy]

OldP made a statement a while ago about "small, small". I run Campy and can NOT find the s/s process, anyone care to elaborate......:)

[christian]

Small small through the derailleur and make sure there is some tiny bit of tension. Then run big-big through the derailleur and make sure it's happy with that number of links. Cut/install.

I don't do this for 2x9 and 2x10 MTBs where having a taut derailleur is helpful.

[oldpotatoe]

OldP made a statement a while ago about "small, small". I run Campy and can NOT find the s/s process, anyone care to elaborate......:)

Wish I could find the diagram..small CR, smallest cog..about 5-15mm from chain to lower knuckle of RD..works for everything.

about 1:37 of this
http://www.campagnolo.com/jsp/en/servicevideo/videocatid_4_videoid_7.jsp

[floxy1]

In big/big combo derailleur cage should be at 4:00. That had always worked for me

[ctcyclistbob]

Large, large with derailleur cage at a 45 degree angle.

[lhuerta]

SMALL / small ...period!
Lou

[Mark McM]

I feel that small-small is the best in most cases because it covers the widest variation of cassette sizes. Riders that swap wheels or cassettes often may use widely different largest sprockets, but the smallest sprockets on cassettes differ very little - sprockets on the small end only vary from an 11T to a 13T (only a 2 tooth spread), whereas the largest sprockets might vary from a 23T to a 32T. Sizing a chain based on the small-small combination leaves the longest amount of chain possible, leaving the largest amount of room for variation in the large-large combination.

In the event that a cassette or chainring swap at a later time leaves the chain too long, it is easy to remove a link or two; whereas if a chain was originally sized for large-large and at later date it was found that the chain was too short, it would be inadvisable to add extra links to the partly worn chain.

Finally, using the longest possible chain reduces chain tension on the bottom run, which reduces frictional losses at the pulleys. It is true that this is a small difference, but chain links only weigh 2 - 3 grams each, so the extra weight of a few chain links is still more than compensated for in reduced friction loss.

One of my bikes has a Campagnolo short cage rear derailleur, and by sizing the chain for short-short (longest possible chain), I'm able to swap from a combination of 53/39 chainrings and 12/23 cassette to a combination of 52/36 chainrings and a 13/29 cassette and back again with the same chain.

[josephr]

Big-Big add a link.

+1 - but I add two.
Joe

[carpediemracing]

I feel that small-small is the best in most cases because it covers the widest variation of cassette sizes. Riders that swap wheels or cassettes often may use widely different largest sprockets, but the smallest sprockets on cassettes differ very little - sprockets on the small end only vary from an 11T to a 13T (only a 2 tooth spread), whereas the largest sprockets might vary from a 23T to a 32T. Sizing a chain based on the small-small combination leaves the longest amount of chain possible, leaving the largest amount of room for variation in the large-large combination.

In the event that a cassette or chainring swap at a later time leaves the chain too long, it is easy to remove a link or two; whereas if a chain was originally sized for large-large and at later date it was found that the chain was too short, it would be inadvisable to add extra links to the partly worn chain.

Finally, using the longest possible chain reduces chain tension on the bottom run, which reduces frictional losses at the pulleys. It is true that this is a small difference, but chain links only weigh 2 - 3 grams each, so the extra weight of a few chain links is still more than compensated for in reduced friction loss.

One of my bikes has a Campagnolo short cage rear derailleur, and by sizing the chain for short-short (longest possible chain), I'm able to swap from a combination of 53/39 chainrings and 12/23 cassette to a combination of 52/36 chainrings and a 13/29 cassette and back again with the same chain.

+1 (or whatever)

Small-small, longest possible chain where there is tension on the rear derailleur cage.

If I'm using a within-spec rear derailleur then the chain will definitely be long enough in the big-big, if the amount of chain wrap is within the rear derailleur's specs. I haven't done the math on it so technically I may be wrong but in my case the small-small has always resulted in a longer chain than the big-big + a pair of links (meaning one inner, one outer), at least with the normal cassettes I use (11 or 12 to 23 or 25).

[Black Dog]

Wish I could find the diagram..small CR, smallest cog..about 5-15mm from chain to lower knuckle of RD..works for everything.

about 1:37 of this
http://www.campagnolo.com/jsp/en/servicevideo/videocatid_4_videoid_7.jsp

You beat me too it. This method is fool proof and will result in the longest workable chain for your bike. Any other method is overly complicated.

[stien]

FWIW I use the small-small make sure it doesn't drag on the RD method and I've never gotten the chain stuck in big-big. You literally make the chain as long as possible this way. I've even tried a 52-32 combo with a chain made to 39-11.

[Ralph]

I use the small to small method. Run as many links as I can. Never know when I might want to put a big cassette on and need some more capacity.

Another reason for small to small.....If I get chain too slack, can always take 2 more links out. Using big to big method , if I want to run more links for some reason, have to use a link plus another quick link to lengthen chain....a pain. It's not like old days when you could get out your chain breaker tool and add a few links back in. Link pins then stuck thru and out a little , not flush like now, so that you could put links in fairly safely if you were careful.

[mtechnica]

The instructions with campy chains say to use the small small method.

[KidWok]

Tai, if while cycling in Ireland someone were to ask you how to get to Tipperary, I assume you would tell them to simply pedal until they got there? ;)

http://www.shelleymunro.com/blog/wp-content/uploads/Tipperary-Ireland.jpg

I probably would...because it's along long way to Tipperary by foot. :)

Tai