42 is quite a small largest chaining - it is actually sometimes found as the smallest chainring on road bikes.

A 48 would be an acceptable high gear for most people, but so much so that when pedalling at a reasonable cadence, most people would not get into the big chainring/smallest 2 or 3 cogs very often.

THe good thing about training your legs to spin is that it is a win-win-win - you will go faster, you spend nothing, and it is better for your body. As you age and you start to have more joint pain, spinning higher rpm to go the same speed and distance will offer releif and less wear and tear.