FYI, only get the 24mm if you have 44cm or wider bars.
26mm will work on 31.8mm bars, but you can't mount them right next to the stem and you'll need a rubber shim.
31.8mm mounts near the stem on 31.8mm bars, but IMO, it gets too close and causes cable routing problems. It is possible to mount it closer to where you actually hold the bars, but you'll need a rubber shim, because the bars taper off to 24mm at that spot.