Hello all. I have an issue i woiuld like your opinion on. I posted it here a few months back but seeing as I havent riding the bike alot lately I let it slip. Time for me to get it sorted out. Roughly around the 15000km mark, my bike started displaying what can only be described as a pulsing/vibration, peaking at around 3200rpm, and only in 5th gear. Every other gear is fine. I took it into the local BMW dealer and they gave me the usual line, feels normal. Whatever. I was notified of a chain recall when the bike was at 18000kms. Got the chain done and to my surprise the pulsing/vibration was no more, great. Recently I took the bike away on a long trip. Everything was going fine till the bike hit around 30000kms, when the pulsing vibration came back. Once again peaking at around 3200rpm, and only in 5th gear. All up i guess I notice it to some degree for a range of about 500rpm. It is very noticable, to the point where I dont like using 5th gear in that range at all. I feel it in the hand grips and through my feet. It is very constant, very rhythmic. I tested it on the way home from work last night. It pulses at a rate of about 160 pulses/vibrations per minute @3200rpm, which is about 73kph, or close to it. If I clutch in and coast at that speed the vibe is gone, so it is when the bike is under load only, so I assume that it isnt the chain or sprockets. I have tested the chain for stretch, checked it right the way around the length of the chain and it appears to be fine. I could be wrong. I dont have a huge amount of mechanical knowledge, but I have a couple of queries about this. I originally thought it may be chain or sprockets, due to when it happened the first time, and i had the chain recall done, it seemed to fix the problem. What i cant figure is that if it was a problem with a certain point on the chain, or a sprocket, then at 72 kmh the pulses would be alot faster that 160 per minute, given the length of a chain or the circumference of a sprocket, you get me?. I dont understand what would cause a constant 160 vibes per minute at that speed. I dont understand how the internal gearing works but once again, Im sure nothing has a cycle rate? that slow. I dont just want to go out and buy a chain, sprockets and chain tool straight away, a few hundred dollars worth. It could be wasted money. Any thoughts?.