Cannondale’s unique single-legged Lefty fork is surprisingly stiff, light and reasonably controlled, but we can’t ignore the high price. The single legged design has been evolving since 1999 but has only recently been reformatted and made available to fit to other bikes.
The upside-down fork uses a keyed bushing and fixed tapered axle for precise steering and braking stiffness at a very low weight. Eighty-eight needle bearings give an ultra-supple, ground-tracking start to the 140mm RockShox derived air spring stroke.
The PBR damping is impressively consistent and controlled, with a press on, slap off lockout/rebound adjuster just below bar level. The Lefty is pretty linear in standard form so braking dive is an occasional issue, but it can be tuned internally.
The offset fork is compatible with 1.125 and 1.5in head tubes, although it does require a dedicated wheel (Lefty hubs are £80). Loosening the brake to remove the wheel is a faff. You can fix punctures with the wheel in situ though, and it’ll never get blocked however heavy going the mud is. Cost is more likely to be a sticking point.