When trying to build a bike to look like a fixie, I have come to the stage of installing the wheels measuring 27 and replace the transmission system into a single rate. My bike is initially normal mountain bike that uses a multi-speed transmission. And it turns out the chain can not be used for the single speed transmission. I thought I had bought the wrong sprocket.

Apparently there is a fundamental difference between the chain used on single speed with multi-speed chain. Chain single speed has a width of 1 / 8 "and multi-speed chain has a width of 3 / 32", this size difference, of course, led to my multi-speed chain  can not get attached to my new single speed.

Above, single speed chain. Figure below, multi-speed chain.