I have a 34/22 double chainring setup with a chain device. No matter how I setup the front mech, if I’m in first, second or third gear on the cassette and I shift from the 34 ring to the 22 on the front, it over shifts and drops the chain onto the bottom bracket. I even set the limit screws so it’s rubbing when in 22 ring, but it’s still happening. Can’t understand it. Help please.

what chain device?

It’s a Gamut dual chain device- thanks

I’ve got one of those on my bike and its been faultless. I’m no expert but if the chain was previously set up for a triple set up i think you can reduce the length to suit a double although I haven’t done this on mine.

Have you positioned the roller of the chain device so that it fully tensions the chain? Mine is set so its as tight as possible (Orange Five)

I don’t know if it will affect it but have you checked the position of the roller. You can screw it in/out so that it’s in line with the chain and you secure it with a tiny grub screw. The roller has two positions for each of the rings

Sounds like your front mech’s at the wrong height, it may well need lowering.

Cheers guys. I’ll lower the mech and check the position of the roller. Will let you know how I get on