If the gearing is set up right, you can ride up mountains with old style freewheels. For 23 years I rode a mid 80s touring bike with a 13-30 six cog freewheel on the back and 28-44-48 chainrings. That kind of half step gearing gave me close ratios and only one or two duplicate gears. The bar end shifters could be operated even when I was out of the saddle.
Did a few tours in the rockies and rode it to work nearly all year 'round.