When bike is at Neutral, measuring force which is required to turn wheel takes into account: tranmission shaft and gearbox output shaft resistance as although all cogs are fully meshed but they rotate freely on their shafts ( input + output)
When bike is at 1st gear with clutch in, we measure force which consists of: transmission shaft resistance, 1st gear engaged resistance(ratio), input shaft resistance and clutch drag.
I don't know how much force is added to spin the wheel as a result of engaged 1st gear, but I wouldn't expect to contribute it to 100% of force compared with neutral test. As I mentioned in my earlier post, rear wheel is catching occasionaly and force required to move wheel from stationary is ranging from 4-6kg ( * 9.8). I'm assuming that resitance caused by engaged 1st gear (cogs locked on their corresponding in/out shafts) would not differ as the friction between cog's teeth should be constant, so the only part in engine that works purely on basis of controlled friction is "CLUTCH". The only way to find out how much force is "lost" as a result of engaged gear would be to remove clutch and let gearbox spin freely. I see your point here.
As the wheel is "catching" I can think of warped clutch plates, or some other factor which could be oil, its stickiness at certain temparature and also its volume in clutch chamber.
johnny
