If you want to raise the gearing, which makes more difference (if any), an extra tooth on the gearbox sprocket or one fewer on the rear wheel sprocket? Will either option affect the length of the chain significantly on my Honda CBF250? Wrinklytoad, MCN forums
Both options will alter the gearing, but an extra tooth on the front has a greater effect and is easier to do because it's the same difference as two to two-and-a-half teeth fewer on the rear sprocket. Adding a tooth to the front is also easier to do because it doesn't compromise chain length and wheelbase to the same extent as extra teeth off the rear.