Low end means you gain torque but lose speed. A small gear on your gearbox means you can climb really steep hills or pull really heavy loads. A large gear means you'll go faster but may have to assist going up a hill. With a 17t gear on the gearbox the only way you'll need to assist while in 1(1) is if you're pulling a heavy load behind you. Here is what you'll have with that set up 7000÷18.75×(17:44)×(42:16)×(13÷168)~29.3 mph. Would be your top level ground speed. If you're going downhill let off the gas after 29.3 mph. You'll just be over reving after that. With a 10t gear this is what you'd have. 7000÷18.75×(10:44)×(42:16)×(13÷168)~17.2 mph.