well you don't "need" gears as many people go singlespeed, and the singlespeeders don't "need" freewheels as many people go fixed gear, and fixed gear riders don't "need" brakes as the fixed gear brakes itself, for that matter they don't "need" the bike because many people hike on the same trails totally bikeless. those hikers don't "need" shoes because a lot of people feel closer to nature by going barefoot, those barefoot hikers don't "need" to hike at all because a lot of people are happy staying home and watching discovery channel, those people don't "need" cable because a lot of people get by with just some tomato soup and each other's company.

So no you don't "need" gears, all you really "need" is food, water, and sleep.