Originally Posted by gohabsgo

So, long story ... I wanted to get some lower gears to climb with since I bought my bike years ago in Ontario but now live in BC in the heart of the Rockies. I switched my 9spd 13-25t cassette to a 9spd 11-28t cassette and also switched my crank to a smaller 34t ring on front.

My rear derailleur is a Shimano 105 5800 small cage , so I think it should be able to handle a 28t cog. I measured my chain against my old chain and added links to account for the extra 3 Teeth on the 28t cog. After adjustments, all shifting is OK except the 28t cog which makes slight contact with the derailleur cage wheels.

If the front is on the small 34t ring, this is worse. I think my chain may be too long/short Or perhaps I need some adjustment on the B screw?

Any suggestions are welcome. This is my first major job on my bike.

Thanks.

Larry