Motorcycle, Is max power at crankshaft or output sprocket? 1

[L100]

First, I am not a specialist for motorcycle.

Most of rumors about power of racing bike are talked about the power at crankshaft. But it looks difficult to measure it.
My understanding is that the power is measured at output sprocket on Dyno.
My questions are
(1) Is max power in brochure corresponding to crankshaft power?
(2) If answer of question (1) is Yes, Is there any conversion formula from sprocket power to crankshaft power as standard?

Can anybody tell me clear idea about above question?

Thank you in advance.

 

[GregLocock]

(1) almost certainly

(2) no

The difference between crankshaft power and sprocket power is the gearbox efficiency. At best a pair of gears might transmit 99% of the power, at worst 60%.

I'd guess a typical m/b gearbox would use 3 sets of gears between crank and sprocket, leading to a maximum efficiency of 97%, and a minimum of 21%, although that wouldn't be a gearbox, that would be a furnace.

The efficiency of the gearbox will alter with each gear that is selected - you may find that top is far more efficient than first, for example (it works that way in cars). Cheers

Greg Locock

 

[L100]

Thank you GregLocock.

One set of gear is losing appox. 1% of transmitting power in gear box in maximum efficiency case. That's clear.
Thank you again.