The Trek Marlin is not only Trek’s best selling mountain bike, but also the most searched bike on our website, 99spokes.com, and after spending some time on the bike, I can see why.  I can’t overstate how much the modern, trail-inspired geometry improves the Marlin’s performance on single track trails. Sadly, however, this modern geometry is paired with some other antiquated frame standards that make future upgrades a bit tricker. But if you’re looking for a solid beginner mountain bike or off-road leaning hybrid, the Marlin definitely deserves a spot on your short list!