i've got some shim stack style ones that cost about �35, there good as you can alter the height.

I had them at full height to start with which was 40mm, cables reached and when up on the pegs the bars felt at a great height. But....its all a compromise, as when sat down the bars felt too high.

I've took a shim out so now there at about 30mm whcih feels good when stood up or sat down.

The main problem is when you have an off, the risers seem to twist. You need to loosen it all off, re-align and tighten up. Not hard to do but just annoying.