that's low enough, but gearing down if that's hard for you anywhere is a good call. go up a couple inches at a time if you really want to work on riding higher gears. your legs will be better able to handle those gears if you start low and work up to them. it's like lifting weights, you don't start out trying to bench 400 (or maybe you do, i don't know much about weightlifting, but 400 sounds damn heavy).