Hi there,

Currently considering switching between 12/27 and 12/29 cassettes on a mechanical Campy SR11 drive train (52/39 chain rings), based on total elevation of ride. Question is -- do I have to add 1 or 2 chain links when switching to the 12/29 due to the larger diameter of the biggest ring? I'm hoping not but would like confirmation from the aficionados. Thanks in advance.

Depends really on the length of your existing chain, and how they sized it during installation. You might be fine.

indeed does depend on chain length, but I regularly switch between 12-25, 12 - 27 and 12-29 without having to add links to the chain

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Ride Strong

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I just changed from 12/27 to 12/29 SR and my chain was fine. But like mentioned before, it also depends on your current chain length.

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Pfeiffer's Rennrad Camp and Cycling Coach
Independent HED Wheels/Powertap Dealer

Thanks for the responses -- will give it a try.

Also depends on whether you use the big/big combination. If you avoid it then its not going to be a problem even if your chain was set up at the minimum length for the 12-27 cassette. You should be avoiding that combination anyway, as it will wear your chain/drivetrain a lot and its inefficient (most power loss). Of course if you are racing then its possible to forget in the heat of the moment.

Be aware that changing into big/big on a work stand and spinning away is a little different to changing into that combination under load while riding. Look at the rear derailleur on the stand, feel the cage with your hand, can you move it up and down a little bit, does it have a little bit of play? If it does you are probably fine in that combination-you aren't going to bend or snap something as your frame flexes under power as the chain has a tiny bit more slack to take up.