Updated: Fox F100 RLC FIT £669

Outstanding control and low weight

BikeRadar score 4/5

Fox Racing Shox's flagship cross-country suspension fork trades in the company's long-running open-bath damper design in favour of a fully enclosed 'FIT' (Fox Isolated Technology) cartridge architecture borrowed from the 36 and 40 platforms. 

The FIT design separates the damping oil from air and, according to Fox, virtually eliminates cavitation in rough terrain. Some testers reported better handling on long stepped or rocky descents, but it's difficult to tell with just 100mm of travel on tap here – it's likely more obvious an effect with longer-travel bikes.

The real benefit of FIT in this application is the 71g of weight it saves courtesy of the reduced oil volume. That, plus a few minor chassis tweaks, now makes the 32 F100 RLC FIT one of the lightest Fox forks we've tested at just 1.49kg (3.27lb) with an uncut 1 1/8in alloy steerer – virtually the same as a current non-remote RockShox SID Team.

Though there's less weight than before, everything else we raved about on the old F100 RLC (which remains in the lineup) remains or is even improved upon. Damper and spring rates are spot-on, making for a supple ride over stutter bumps plus excellent control on bigger hits and drops, and an overall light and lively feel in the rough.

Provided you invest the time to dial in the various settings, front wheel traction is superb and brake dive is well controlled, too. No problems getting full travel where appropriate, either.

Chassis stiffness is impressively high thanks to the 32mm-diameter aluminium upper tubes and beefy cast magnesium lower legs with their broad-shouldered arch.  Our test fork does one better with the addition of a 15mm through-axle, which has a positive effect on steering precision in fast, technical terrain when compared to a typical hub's 9mm quick-release skewer. 

Instead of occasionally pinballing your way through rock gardens and off-axis roots, it's now more a matter of point-and-shoot (with a little bit of 'hold on tight') and the overall sense of control is heightened as well. The through-axle is no panacea, mind you, but it does let you charge through certain sections with that little bit of extra speed and control. If you want even more stiffness (and if your frame allows), Fox also offer the F100 with a tapered 1 1/8in-to-1 1/2in steerer.

Whether or not 15QR is justified in light of the industry-standard 20mm system is still a hotly debated topic though. At 94g, the smaller-diameter Fox axle is comparable in weight to RockShox's 86g Maxle Lite and until more companies develop dedicated 15mm wheels and hubs (most are conversions on existing 20mm shells), any significant weight savings owing to 15QR's narrower hub spacing and bearing sizes are still more a matter of potential than reality. Even so, 15QR is an absolute no-brainer as an alternative to standard quick-releases: it's far stouter, much safer and more intuitive to use for novices. 

Alas, all was not perfect with our test fork, as our initial rides were marked by numb hands and an overly harsh feel – tell-tale signs of excess stiction. As it turns out, our oil bath fill levels fell well short of Fox's recommended 20cc per side (about 15cc in one and barely 5cc in the other). The fix was quick to perform (no more than 10 minutes) but it's one consumers shouldn't have to do with a new fork.

Experiences with other forks since this review was first published suggest stiction in the FIT cartridge is far from an isolated incident. The severity of the stickiness varies from fork to fork, although most get better the more you use them. Lack of bob will actually be seen as an advantage by a lot of the racers and fast riders who’ll use the F100 however, so it’s less of an issue than on longer forks.

Otherwise, the magic continues as usual and this is hands-down one of the best cross-country forks on the market – but you might want to keep a bottle of fork oil on hand just in case.

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