jwscab wrote:yeah, I believe 12mm and 10mm. the difference boils down to giving you a little finer adjustment range for a given spring and damping oil due to higher volume of oil/larger piston and larger diameter spring.
To help elaborate:
The big bores are 12mm and the V2's are 10mm. Big bores offer a more plush ride because the shock shaft makes up a smaller percentage of the oil volume displaced when compressed (which can reduce the 'pack' feel). Additionally, since the oil volume is much higher and given the same amount of air in the shock (because it's emulsion), there will be less cavitation and shocks will stay more consistent. Also, the larger oil volume makes them less susceptible to changing viscosity due to heat build up.
The big bore springs are much better because they are simply put 'better designed', particularly when compared to the rear springs. The old rear springs were too long given their diameter and as a result they become 'unstable' and buckle. When the spring buckled with small bore springs they would rub on the shock body which causes additional resistance and an unintended side load to the shock.
It is pretty amazing now days building up a new B5 shock and comparing it to the RC10 shocks, the difference in how free and smooth the new shocks are is amazing. We've certainly come a long ways!!