# Chain length for alternating between 28t and 32t cassettes



## TmB123 (Feb 8, 2013)

As per the thread title I currently run two wheelsets on my adventure bike both with Shimano 11 speed 11t-28t cassettes and Dura-Ace short cage RD. Looking to put an 11t-32t cassette on one of the wheelsets for a bit more off road climbing capability and change out the RD to an Ultegra medium cage to handle the 32t. FWIW running 50/34 rings up front with DA fd.

My question is, if I size the chain for the 32t, is there any issue with chain length or any adjustments required when swapping back to the 11-28? I don't think so as it would just be similar to being in the 27/28 on the bigger cassette, I think, but just wanted to check as long as I size the chain for the 50/32 combo, I should be golden?


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## Lombard (May 8, 2014)

TmB123 said:


> As per the thread title I currently run two wheelsets on my adventure bike both with Shimano 11 speed 11t-28t cassettes and Dura-Ace short cage RD. Looking to put an 11t-32t cassette on one of the wheelsets for a bit more off road climbing capability and change out the RD to an Ultegra medium cage to handle the 32t. FWIW running 50/34 rings up front with DA fd.
> 
> My question is, if I size the chain for the 32t, is there any issue with chain length or any adjustments required when swapping back to the 11-28? I don't think so as it would just be similar to being in the 27/28 on the bigger cassette, I think, but just wanted to check as long as I size the chain for the 50/32 combo, I should be golden?



Yes, as long as the chain is long enough for the 50/32 combo, you are good.

However, you should still check your rear derailleur limit adjustments when changing between wheels. Even similar wheels and cassettes can be off ever so slightly as to throw your chain into your spokes!  Better safe than sorry!


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## tlg (May 11, 2011)

You should size your chain using the small-small method. Then you'll have the correct amount of chain for any gear combination.
But yes, if your chain is sized for the 32, you'll have no problem going to 28. This is what I do on my cross bike. No issues at all. I'm fortunate that my wheels direct swap with no adjustments needed. But as Lombard pointed out, you may need to make slight adjustments to your RD limits, cable, and B-tension.


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## TmB123 (Feb 8, 2013)

Thanks.
What is the small-small method? I've always used the Shimano way of doing it.


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## tlg (May 11, 2011)

TmB123 said:


> Thanks.
> What is the small-small method? I've always used the Shimano way of doing it.


https://www.youtube.com/watch?v=WnRxNHkRh8Q
https://www.youtube.com/watch?v=QuhHn7HaZcQ 

Chain How-To - Part 1 - Slowtwitch.com


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## TmB123 (Feb 8, 2013)

Thanks - watched the first video, easy enough to do, curious, what is the benefit of doing it small - small than the way Shimano recommends to do it (i always figured they would probably know best)?


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## TmB123 (Feb 8, 2013)

Actually, thinking about it, if you just size small-small, how does that take into account the largest cog size whether it be 25,28,32,34 etc or does having the RD so far back with that method make the chain long enough for any cassette size?


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## tlg (May 11, 2011)

TmB123 said:


> Thanks - watched the first video, easy enough to do, curious, what is the benefit of doing it small - small than the way Shimano recommends to do it (i always figured they would probably know best)?


The small small sizes your chain to the longest length your drivetrain can handle. Allowing you the greatest range of gears possible.
Read the slowtwitch link, it explains it thoroughly.


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## TmB123 (Feb 8, 2013)

tlg said:


> Read the slowtwitch link, it explains it thoroughly.


Just read the article, makes sense, for some reason I thought that would be shorter, thanks again.


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## rochrunner (Jul 11, 2006)

I had a bike with a gear combo that would not technically work with my rear derailleur at the limits. However, you really should never be in the large-large or small-small gears in actual riding, so I just made sure to keep track of my gears and not cross chain too much.

Sent from my SM-T700 using Tapatalk


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## tlg (May 11, 2011)

rochrunner said:


> However, you really should never be in the large-large or small-small gears in actual riding


Not true.


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## Lombard (May 8, 2014)

tlg said:


> Not true.



True or not, you may accidentally go there. If you do go into the large/large and your chain isn't long enough and binds, worst case scenario you could rip your rear derailleur and even a chunk of your frame off the bike.


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## cxwrench (Nov 9, 2004)

rochrunner said:


> I had a bike with a gear combo that would not technically work with my rear derailleur at the limits. However, *you really should never be in the large-large* or small-small gears in actual riding, so I just made sure to keep track of my gears and not cross chain too much.
> 
> Sent from my SM-T700 using Tapatalk


Says who?


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## Blue CheeseHead (Jul 14, 2008)

Small-Small gives you the longest possible chain that will properly work with the derailleur.

Big-Big will give you the shortest possible chain that will work with a given cassette.

If one is sizing for the maximum size cassette that they want to run, start with big-big. Worst case is that the chain will be too long to run in the small small combo, resulting in chain slap in that combo.

If one goes small small it is possible that the chain will be too short to run on the big big combo of a particularly large cassette. That can cause serious damage.

If you are operating within the specified limits of a derailleur, small small is the way to go. If you are pushing the limits to get an out of spec large cassette, Big Big is the safer method.


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## spdntrxi (Jul 25, 2013)

I've gone 26T to 30T with same chain.(sized for 26T using small,small method... worked. I just stayed away from BIG BIG.. which I do anyways.


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## crit_boy (Aug 6, 2013)

We just had this thread two weeks ago, and two weeks before that, and two weeks before that. . . 

FWIW, Shimano tech docs say a big/small method for cassettes with a large cog of 27T or less and big/big for cassettes with 28T or more (page 9, link).


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## TmB123 (Feb 8, 2013)

crit_boy said:


> We just had this thread two weeks ago, and two weeks before that, and two weeks before that. . .
> 
> FWIW, Shimano tech docs say a big/small method for cassettes with a large cog of 27T or less and big/big for cassettes with 28T or more (page 9, link).


It would seem to be a popular question then - but wasn't on my radar until last night.

Yep, that's the Shimano method that I referenced earlier and the way I have always sized my chains, however it seems that with the people who actually work on this stuff, have other ideas with how it works in the real world.


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## Jay Strongbow (May 8, 2010)

Lombard said:


> Yes, as long as the chain is long enough for the 50/32 combo, you are good.



Maybe, maybe not. See BlueCheesehead's post below. There's no certainty being good to go with what he's trying to accomplish is even possible with a DA short cage.

FYI, an Ultegra rear der. that's spec'ed for max 32 can be found quite cheap. So if you can't get the short cage to do what you want to do that's probably your solution.


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## TmB123 (Feb 8, 2013)

Jay Strongbow said:


> Maybe, maybe not. See BlueCheesehead's post below. There's no certainty being good to go with what he's trying to accomplish is even possible with a DA short cage.
> 
> FYI, an Ultegra rear der. that's spec'ed for max 32 can be found quite cheap. So if you can't get the short cage to do what you want to do that's probably your solution.


Hey Jay, as per original post, definitely geting an Ultegra medium cage RD to handle the job.


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## Lombard (May 8, 2014)

Jay Strongbow said:


> Maybe, maybe not. See BlueCheesehead's post below. There's no certainty being good to go with what he's trying to accomplish is even possible with a DA short cage.
> 
> FYI, an Ultegra rear der. that's spec'ed for max 32 can be found quite cheap. So if you can't get the short cage to do what you want to do that's probably your solution.


Blue Cheesehead's post #14 is spot on. What I was saying is that if the OP's existing chain worked in the large/large combo, he was good to go since it obviously worked with the smaller cassette.

FWIW, while a chain that is too loose will slap and won't shift as smoothly as one correctly sized, one that is too tight can product catastrophic results in the large/large combo - unless the rider is vigilant enough to never go there.


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## Lombard (May 8, 2014)

Blue CheeseHead said:


> If you are operating within the specified limits of a derailleur, small small is the way to go. If you are pushing the limits to get an out of spec large cassette, Big Big is the safer method.


This.


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## Jay Strongbow (May 8, 2010)

TmB123 said:


> Hey Jay, as per original post, definitely geting an Ultegra medium cage RD to handle the job.


Whoops, sorry man. I missed that.


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## TmB123 (Feb 8, 2013)

Jay Strongbow said:


> Whoops, sorry man. I missed that.


No worries at all :thumbsup:


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## TmB123 (Feb 8, 2013)

Set it up small - small with the Ultegra medium cage RD, 11-32 cassette and 50/34 rings. When shifting into the big-big combo there is still heaps of chain length and derailleur capacity.


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## mfdemicco (Nov 8, 2002)

I had a similar arrangement. I wanted to alternate between a 28 and 32. I used the big-big method on the 32. I checked and it so happens to be the same chain length as if I had used the small-small method. Huh...


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## cxwrench (Nov 9, 2004)

mfdemicco said:


> I had a similar arrangement. I wanted to alternate between a 28 and 32. I used the big-big method on the 32. I checked and it so happens to be the same chain length as if I had used the small-small method. Huh...


Because you're using the biggest cassette that the derailleur will work with. Try sizing big/big with a 23 or 25, even a 26...your results won't be the same.


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## mfdemicco (Nov 8, 2002)

cxwrench said:


> Because you're using the biggest cassette that the derailleur will work with. Try sizing big/big with a 23 or 25, even a 26...your results won't be the same.


Yes. My derailleur was also at capacity because I was using a 22-32-44 crankset and an 11-32 cassette so it should be expected to work that way.


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