Campagnolo Chain Sizing

Discuss light weight issues concerning road bikes & parts.
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Westbank
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Joined: Sun Apr 03, 2005 4:39 pm

by Westbank

There are many ways to determine the proper length of a chain but I had a specific question about the technique recommended by Campagnolo.
Campagnolo's technique is to put the chain on the smallest sproket and chainring and the gap between the front pulley and chain must be between 8mm and 15mm. That's all good. This will garantee to have to longest possible chain.

But what if you keep the same chain and change the cassette: jumping from a 11-23 to a 11-25 or even to a 11-29 ? The derailleur cage will be streched out on the 29 ?

Is everyone running Campagnolo chains using this sizing technique ? Any issue when changing cassettes (with bigger or small gearing) ?

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Calnago
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by Calnago

Yes, it’s all good, unlike it might be if you were to use the big/big plus 2 links on a small cassette for example, then try to throw on a larger cassette. As long as you stay within the specified capacities of the derailleur and chainring combos and cog sizes you will be fine. For instance, using a 39/53 chainring combo, with the chain set this way I can run any cassette from 11/23 through to 11-29 (talking 11sp systems here). In my case, that’s 110 links, chainstays ~411-415mm. However, if I wanted to run a 36/52 combo up front, then using the same technique will result in a chainlength of 108 links. I have however found that as long as I have say around 5mm clearance (where the diagram shows 8mm), that is good. And I’d rather err on the longer side than the shorter side, so that minimal stress is put on the derailleur when switching to wheels with the 29tooth cassette on it. Either way, all you have to do when swapping cassettes of significantly different sizes is to adjust the H screw a bit to ensure the upper pulley teeth are as close to the largest cogs teeth as possible (without jamming or creating chatter) when in the small ring/largest cog combo.
Now, one of the pluses of the new 12sp mechanical groupset is that for chainstays between 405-415mm, it’s easy... 110 chainlinks, period. And the beauty here is that you can swap between any of the three chainring combos up front (34/50, 36/52, 39/53), and either of their 11/29 or 11/32 cassettes at the rear and not have to change chainlengths. Only if you have chainstays beyond the 415mm guildeine would you need to go to 112links. And I’m not sure about using this system with the newest 11/34 cassette, as I haven’t worked with it, but I think I read somewhere that the 12sp mechanical Record and Super Record groups will work with it too, but don’t quote me on that last part. The other thing with the new 12sp stuff is that the most critical adjustment of the derailleur (aside from the limit screw and cable tension), is that you really want to make sure that the chain, when in the smallest cog at the rear, does not take an upward trajectory (relative to the upper pulley). The “wrap” is so encompassing that it is actually possible for the upper pulley to start wrapping around the smallest cog in the front so that the chain is angling down as it leaves the upper pulley and engages the smallest cog as early as about the “5 o’clock” position when looking at the rear cog as if it were a clock face. But once you have that set you just let the derailleur settle where it does in relation to the largest rear cog. And all will be super slick.
Last edited by Calnago on Fri Aug 02, 2019 4:40 pm, edited 1 time in total.
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by Weenie


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Westbank
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by Westbank

Thanks Calnago. Really appreciate the detailed information. I wanted to make sure I didn't ignore something important about the chain length when switching between different cassettes.

Thanks also for the info on the 12s. Didn't know that.

graeme_f_k
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by graeme_f_k

Calnago wrote:
Fri Aug 02, 2019 4:40 pm
Yes, it’s all good, unlike it might be if you were to use the big/big plus 2 links on a small cassette for example, then try to throw on a larger cassette. As long as you stay within the specified capacities of the derailleur and chainring combos and cog sizes you will be fine. For instance, using a 39/53 chainring combo, with the chain set this way I can run any cassette from 11/23 through to 11-29 (talking 11sp systems here). In my case, that’s 110 links, chainstays ~411-415mm. However, if I wanted to run a 36/52 combo up front, then using the same technique will result in a chainlength of 108 links. I have however found that as long as I have say around 5mm clearance (where the diagram shows 8mm), that is good. And I’d rather err on the longer side than the shorter side, so that minimal stress is out on the derailleur when switching to wheels with the 29tooth cassette on it. Either way, all you have to do when swapping cassettes of significantly different sizes is to adjust the H screw a bit to ensure the upper pulley teeth are as close to the largest cogs teeth as possible (without jamming or creating chatter) when in the small ring/largest cog combo.
Now, one of the pluses of the new 12sp mechanical groupset is that for chainstays between 405-415mm, it’s easy... 110 chainlinks, period. And the beauty here is that you can swap between any of the three chainring combos up front (34/50, 36/52, 39/53), and either of their 11/29 or 11/32 cassettes at the rear and not have to change chainlengths. Only if you have chainstays beyond the 415mm guildeine would you need to go to 112links. And I’m not sure about using this system with the newest 11/34 cassette, as I haven’t worked with it, but I think I read somewhere that the 12sp mechanical Record and Super Record groups will work with it too, but don’t quote me on that last part. The other thing with the new 12sp stuff is that the most critical adjustment of the derailleur (aside from the limit screw and cable tension), is that you really want to make sure that the chain, when in the smallest cog at the rear, does not take an upward trajectory (to the upper pulley). The “wrap” is so encompassing that it is actually possible for the upper pulley to start wrapping around the smallest cog in the front so that the chain is angling down as it leaves the upper pulley and engages the smallest cog as early as about the “5 o’clock” position when looking at the rear cog as if it were a clock face. But once you have that set you just let the derailleur settle where it does in relation to the largest rear cog. And all will be super slick.
11-34 / 12s the chain length rules are the same. The derailleur cage length is the same, the difference in the Chorus RD (11-34 capable) and the RE / SR RD (11-32 capable) is only in the rear cage plate and the placement / size of the upper chain guide that prevents the chain over-riding the inner cage plate at the guide pulley, should the chain be forced off the pulley for any reason.

The motivation behind the Campagnolo small-to-small method, initiated in the 8s era and kept to, all the way through to 11s and, in fact, still used on 12s EPS, is that provided the user doesn't abuse the capacity of the RD in terms of the cassette, for any given crankset, the user can swap in any cassette and they'll have enough chain.

It builds in an allowance for different lengths of hanger, different starting sprocket sizes and differing positions for the H-Screw, hence the large 8 - 15mm range given, that Calnago refers to. That allowance can actually be "abused" slightly - as Cal notes, as small as a 5mm clearance can be used but the general recommendation is for a wider one. Likewise, at the other end, a very slightly larger clearance than 15mm works but here, caution needs to be exercised & there is actually no point in abusing the properties of the derailleur at that end of the adjustment range - in fact it could be seriously counter-productive.
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bm0p700f
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by bm0p700f

If you don't change your cassette then problem avoided.

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Calnago
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by Calnago

bm0p700f wrote:If you don't change your cassette then problem avoided.
But that was exactly the OP’s question... regarding chainlength when changing cassettes.
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fogman
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by fogman

According to the Campagnolo website the Chorus 11-34 cassette is not compatible with the Record/Super Record 12 rear derailleur. Although I don’t quite understand the explanation from @graeme_f_k.

https://www.campagnolo.com/US/en/Compon ... _sprockets


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Calnago
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by Calnago

Sounds like the chain length would still be the same for the 11/34 cassette as the cage lengths are identical but that the rear cage plate (and corresponding chain guide) is different from Rec/SR. I’ll have a closer look but I don’t have a 34 tooth cog to test what exactly the issue might be with the Rec/SR rear cage plate as it pertains to the 34 tooth cog.
Colnago C64 - The Naked Build; Colnago C60 - PR99; Trek Koppenberg - Where Emonda and Domane Meet;
Unlinked Builds (searchable): Colnago C59 - 5 Years Later; Trek Emonda SL Campagnolo SR; Special Colnago EPQ

by Weenie


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