Join Date: Jun 2013
Location: Central West NSW, Australia
You "should" be in whatever gear allows you to pull away smoothly and without lugging. Exactly what gear that is will depend on road speed, loaded weight, road in/decline, altitude, tyres, sprocket sizes and tuning. If you snap open the throttle and it lugs before speeding up then you're in too high a gear, if it sounds like you're reving the ring out of the bike then you're in too low a gear.
To put it another way, does the bike pull away well enough at that speed in that gear to get you out of the way of an oncoming shyt storm? If yes, good. If no, drop a gear. Is the engine lugging? If no, good. If yes, go down a gear. Does the bike sound like a 250 four-pot (errrr thimble) because it's reving so hard? If no, good. If yes, go up a gear.
Speed/gear relationships in the manual are general suggestions, not hard and fast rules. I find my 650 is happier if I keep it over three grand on the tacho with stock tyre and sprocket sizes, three and a half if I want a little more punch in traffic, and I change gear to make sure I don't go under that. Ymmv.
"I've recently come to the realization that true happiness can often be found at the bottom of an empty gas tank" - Prime