80% rider 20% bike. Take a look at who's riding those machines and who's managing them.
It is interesting to see certain manufacturers dominate a particular series though. Harley dominated with the XR 750 the Ducati Darmah 900 ss was dominant back in the day ( back in the seventies ) and that may be because the rule books were written around the bikes in question to begin with. So if anybody else wanted to play in their sandbox they were just asking for it.
That's why, after awhile, manufacturers get together and come up with new rules. In WSB Ducatis have always been allowed to polish up pretty much everything on the inside and I think it even goes so far as letting them modify the crank. They admit they need extra mods to keep up with 1000cc bikes and so, now we have the 1098 with more displacement but a few more restrictions on mods than before.
Of course it won everything, but look whos riding the bike. (Troy Bayliss)
Suzuki is dominating AMA Superbikes in this century but now look what happens. Rules changes for AMA Superbikes in '09.
I'm sure everybody thought Yamaha had an unfair advantage when they won 6 Grand Prix Championships in 9 years. But look at the legends that rode for Yamaha.
V-twins will all ways have concessions made for them if they are going to race against inline fours. People still love v-twins and want to see them race against the fours so organizers try to seek a balance but give the v-twins too much of an edge. That is WSB.
AMA is one inline four (Suzuki) whipping everybodys ass. (for now) AAARRGGGHHH me mateys, but to the victor go the spoils.
The question I have is could Mladdin and Co. have done it on a Fireblade or and R1? or did Suzuki have an inside track on what the rules would be in advance? as has been alleged in the past.
Personally, I think it is still 80% rider and 20% bike.