Originally Posted by DAKEZ
MOST Harley and other Cruiser riders ride at WAY TOO LOW of an RPM while cruising down the highway.
Your 3000 RMP was actually spot on when it comes to V-twin cruisers. The Sweet Spot for a Twin cam is going to be found somewhere between 2900 - 3100 RPM's (best cooling, fuel economy... ) MOST get lugged and are being ridden in 6th gear when they should be in 4th.
In-line twins, triples and four cylinder bikes will of course be MUCH higher.
It isn't based on engine layout, fwiw. 3000 RPM is about the minimum that my V twin really likes to see. The engines end up showing that trend because of the type of vehicle that each typically ends up in, though. The I4 in my GS750 is fine running from 2-4k rpm all the time if I'm riding sedately, but that would be miserable on a sportbike.
Originally Posted by windmill
Low RPMs are less "stressful" on the rider when doing lots of miles.
This is actually true. Even if you aren't specifically listening for it, your brain processes all the sounds that your ears hear. More RPM typically means more noise, and at a higher frequency. Smaller engines have to rev higher to make power, typically, and usually make a bit of noise doing so. Those things do contribute to fatigue, even if it isn't inherently bad for the bike. That said, if you can't hear the engine over the wind or it's just that quiet, then the RPM won't make any difference to fatigue.