Why isn't it an overdrive? I'm sure that OD doesn't stand for overdose in the manuals. Kwak considers it an overdrive. Just wondering...
Is this question in jest?
We're talking about transmission gears and transmission gear ratios. The primary purpose of the transmission is to change it's input shaft speed relative to it's output shaft speed. That doesn't include the engine power available, the final drive ratio, or the wheel & tire diameter in the gear ratio equation.
If the transmission input speed is greater than the transmission output speed, the gear is a under-drive.
If the transmission input speed is equal to the transmission output speed, the gear is a direct-drive.
If the transmission input speed is less than the transmission output speed, the gear is a over-drive.
The Wikipedia description is weak at best. Saying the term overdrive is dependent on the power output of the engine, and what it can do at the wheels, is not based on anything tangible. Put a 20' sail on the front of the bike, and second gear becomes an overdrive in a head wind. With the proper tail wind, there would be no overdrive at all.
I fault Kwak for not using proper terminology with their gear selection display (Marketing spec'd, I'm sure). Heck, they probably authored the Wikipedia entry as dis-information to cover their marketing jive ("OD").