Biker armies do not work.
Combined arms do work.
Have a couple of Rhino/Razorbacks and full squads to aid with your objective holding and adding in missing heavy weapon support (250 points brings you 2 Heavy Weapons to the table, as well as a potential 2 more squads capable of holding objectives).
Scout Bikes don't really work. There only real benefit to the army is bringing the Astartes Grenade Launchers. The mines aren't that effective, and against the armies it's useful against, the few losses aren't going to damage them all that much.
Take attack bike squads of 2 instead.
Also, always give your Sergeant a Powerfist. Means it can take on enemy Monstrous Creatures. And lastly, I'm not a fan of the Plasma weapons. With your speed, mass meltaguns is less of an issue, the additional penetration, as well as being able to Instagib enemies like Nobz, Paladins, and Space Marine heroes.
Obviously, this means you miss out on horde capabilities (as let's face it, TL Bolters don't really cut it), so at the least, a couple of Dakka Predators or Sternguard in a Rhino with combi-weapons can really tip the tide.
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