Quads are awesome for quietly trundling up places you'd never get up on bike. When caving we use farm quads now and again, usually we keep piling on bods and packs 'till the logistics gets a bit much, and then off we go! We're usually in horribly steep, slippery terrain.
But nah, wouldn't want to ride one on the road for any real distance, and bikes are way faster in less challenging terrain.
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