I never notice the Rebel having much vibration. It has a high frequency buzz at high speed/wide open throttle. All engines have harmonic vibration. It happens only at certain rpms, or at least is a lot more noticeable at certain rpms. Changing the gearing could change the road speed at which the harmonic vibration is worse. The Rebel is a 360 degree engine, which means the pistons go up and down together. And it has no counterbalance. It is going to vibrate more than a 180 degree engine. Personally I wish they had designed it with a 270 degree crank to give it some character, but the Japanese manufacturers don't like character. My old 1966 Triumph Bonneville would literally move across the garage floor if you revved it on the centerstand. And my current Sportster 1200 is like riding a jackhammer down the road. It shakes so much at idle that it looks blurry. The mirrors are worthless at all speeds.