Yeah bikes are amazing, especially with white scars doctrine. Cause you get +1 jink and ignore dangerous terrain, so first turn you drive, then turbo into cover and you have a 2+ save, then next turn assault which they then benefit from the +1 str for Hammer of Wrath. Also I would suggest maybe instead of the chaplin take a Count-as Khan, cause he is only 150 points, 40 more than your chaplin, but he is stronger, and gives all your bikes and dedicated transports scout, so now its even easier to get into combat. Also since bikes are relentless it means taking two grav guns on them gives you the full salvo shots, and then still allowing you to assault, which is devastating against monstrous creatures and other heavily armoured units. I mean Against termies thats 8 shots, 6 hit, 5 wound, and only 1 saves so you kill 4 termies before you even charge (this is of course on average I can not be held responsible for your marines being crosseyed or the terminators being protected by storm shields and a divination psyker.
When life gives you lemons..... BLOOD FOR THE BLOOD GOD!