Engine speed vs road speed
One line per gear. Solid lines are the focus setup, dashed lines the comparison. The shaded band is where the exhaust gets loud.
Shift pattern
Riding through the gears with upshifts at the same rpm. Each vertical drop is an upshift; the dot at the bottom is where the engine lands in the next gear. Pulling away starts with the clutch slipping at your launch rpm. Focus setup solid, comparison dashed, same setups as the chart above.
Rear-wheel torque by gear
Engine torque × overall ratio × drivetrain efficiency. The grey curve is what the road takes (wind, rolling resistance, and the highway grade) expressed as wheel torque. The gap between a gear's curve and the road curve is what's left to accelerate with.
Acceleration available
Solid: best gear at each speed (what you get if you downshift). Dashed: stuck in 6th. This is the number that decides how passing feels.
Acceleration benchmark
A full-throttle standing start, the way magazines measure it: clutch slipped at the launch rpm until 1st hooks up, then flat-out upshifts. Speeds here are true (GPS) mph so they compare with published tests. Open dots mark each upshift.
Highway
Passing
Hill start in 1st
Gear equivalence
Rear-wheel torque multiplication of each comparison gear against the focus setup's same gear and the gear above it. A positive "one gear up" number means downshifting on the new gearing still beats the old gearing in the higher gear.
How this works, and what to trust
Gear ratios. Primary 3.083 and gearbox 3.000 / 2.063 / 1.588 / 1.286 / 1.095 / 0.955 come from owner-posted manual data. One forum post lists the same numbers shifted by one position, so run the tach check: with these defaults, stock gearing gives about 100 rpm per true mph in 6th, which matches owner reports of ~7,200 rpm at 70.
Speedometer. Dash speed reads high on most bikes. Your report of 7,500 rpm around 80 indicated fits a speedometer reading 5–7% high. The G 310 GS takes road speed from a wheel sensor, so a sprocket change should not alter the speedometer, but confirm against GPS after the swap.
Wheel torque. Swapping one sprocket scales rear-wheel torque in every gear by exactly the final-drive change. 16→17 front is −5.9%; 17/42 is only −1.2% versus stock, so it mostly cancels the point of the swap.
Acceleration model. Thrust minus aerodynamic drag, rolling resistance and grade, divided by mass plus the rotating inertia of wheels and engine (the engine term is large in low gears, which softens the loss from taller gearing). Passing and hill times ignore shift time, so they are slightly optimistic for every setup equally. The acceleration benchmark includes shift time (no drive while the clutch is in) and caps acceleration at the wheelie/traction limit.
Hill start. Modeled as a clutch-slip launch holding the launch rpm until first gear catches up. Clutch-out speed is how fast the bike is moving when the clutch fully engages; a higher number means more slipping on a steep start.
Torque curve. The default is an estimate, not a dyno sheet. Absolute times will shift with a real curve; the differences between setups hold up much better because they all share the same engine.