I never really got into “mountain biking”, because for years I associated it with going fast on rough terrain and dodging obstacles, while I like to ramble and mosey and stop a lot. I also like rides where I can walk out my door (or hop off a train or plane) and get on the bike without having to drive somewhere.
I realize my impressions were a narrow caricature of what mountain biking can be, though, and I’ve always enjoyed the bits of off-roading that sneak into rides– the last mile of dirt getting to a camp site from the road, strange muddy paths I find myself on when trying to bypass roads, or detours through parks to avoid main roads, and even when “road biking” I generally run 32mm+ tires to give myself more comfort and flexibility for unexpected detours.
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