Use bar tape - then you can have whatever width you want, whatever colour you want and you can wrap down the rise and onto the centre section, which gives you an extra hand position which is nice if it's very windy.
+1
I've done this on some flat bars. Add some bar gel if you want a chunkier grip.
+1
I've done this on some flat bars. Add some bar gel if you want a chunkier grip.