Bike: 1984 Honda Integra / VT250 F-II D MC08 Engine, 6 speed gearbox On cold mornings, where its been around 0C overnight, and still below 5C when I set off.. I can hear a rather loud grinding noise consistent with wheel speed. The noise is very similar to that of a car accelerating in reverse gear, getting louder as I increase speed. It stops when I drop below about 5km/h and usually stays quiet for a few minutes if I don't go over about 40km/h, else it starts up again. I'm pretty sure its not the rear wheel bearing as I've tried using the rear brake excessively to heat it up and the noise still came back. The other possibility I can think of is gearbox output shaft bearing, since its independant from engine speed. I don't have the tools or confidence to take out my engine and seperate the crankcase considering its my only vehicle.. But would there be a way to stop it from spinning the bearing and getting worse? assuming thats what the problem is. I also don't want to spend a whole weekend changing bearings in the gearbox if thats not the problem. And to top it off, I can't replicate the problem when off the bike to listen for where the noise is coming from. - Chris : After conferring with dad for a while about it, he's confident it would be wheel rather than gearbox. Since the gearbox is constantly floating in oil the bearing wouldnt have dried out, and any noise of it spinning on itself should be muffled by the oil.