the bike rule is for bikes as Troops not 1 unit
i can not help you out much with this as i find
ork foot armys work alot better

i find i can't bring myself to pay 25 pts a model if there not fearless or have and they shall know no fear.
you will lose melee alot and have 8 or 9 bikes run down
but if you REALLY want a bike army take all the bikes in really small units like 3-5 always have a maxed out nob in the unit then add everything to him. this way each unit is just a nob delivery system
you will give up more kill plts this way but 2 of the 3 missions need troop to hold ground so it works out better having more
next unless you have the modle use killa kan over deff dreds, its cheaper to buy 3 killa kans then 1 deff dread in real money buy about $10 and they are more combat efficient too
when you play
if you get 1st turn set up all your bikes on 1 side of the table which every has more cover, your opponent will set the bulk of there force to stop you flanking them.
this is what you want. take any free shots at them if you can but don't get anyone in your bike units killed.
on turn 2 you turbo-boost for the next 2 turns so your on the other side of table fighting weak or heavy weapons units. the bulk of there force will never keep up and you will never have to fight them.
if you go 2nd for set up do the same and set up all you bike opposet the bulk of there force, this set up has the added bonus of making you look like a noob so your opponent will never see it coming
always remember your a fast army and you never have to fight you can always run away
:note alot of people will try to tell you this is very unorky to run. which is totally untrue.

" Orkses is never beaten in battle. if we win we win, if we die we die so it don't count as beat. if we runs for it we don't die netither, so we can always come back for anuvvergo, see!" ANON