DCnoJ

I have the Super Record Group Set with a compact crank. I'd like to switch between an 11-23 cassette to a 12-27. Will I have to change to a longer chain? If so, can I make an initial change so that I can continually switch between cassettes? Is that even possible?

Thanks in advance.

Servo888

You should use a longer chain with the 12-27, as recommended by manufacturers. Basically running too short of a chain will damage the rear derailleur over time when using big+big sprocket combinations.

But, if you avoid cross chaining with the big+big combination, you can definitely run the same (short) chain.

ericm979

Try to shift (very gently) into the big chainring/big cog. If the chain's too short to make it, you need a longer chain.

I would not recommend "trying to remember" not to shift into it. You'll do it by accident when you're tired on a long ride or busy paying attention during a race. And when you do it'll cost you way more than a new chain would.

goodtimes5

Yes (probably).

jdott

The chain should be adjusted to the small-small, which did not change. The problem is that with a compact and a 27, your der will be crazy stretched to the limit. But if you lengthen the chain, small-small will be rubbing very badly. So, it will never be all the way 'right', but rubbing on small-small is way less of a problem than an exploding der when you cross-chain in the other direction.

jdott

actually, now that I actually read your entry - with a 12 you may actually be able to get it really close.

DaveSSS 

If you followed Campy's instructions for adjusting chain length, you would have no problem at all. Campy suggests using the little/little method that makes the chain as long as possible and able to handle any 11 speed cassette they sell, with one chain length, including the new 12-29.

As an example, I use a 53 inch length for my frames with 405mm chainstays and a 50/34 crank. If a 53/39 is used, the chain length would be 54 inches.