Posted on August 16 2017
It’s been roughly 6 months or so since the first Fox Fit4 dampers were released as part of the 2016 range of Fox forks. Apart from slightly revised external controls/adjusters, there are major differences within the damper that allow for further improved small bump sensitivity, greater support through the entire stroke of the travel, and a much firmer lockout.
The Fit4’s compression circuit controls it’s oil flow in a similar fashion to a CTD FIT damper, however it’s shim stack is where things start to get a little sweeter. Without boring you with the full complexities, The Fit4 uses a smaller number of cleverly sized shims that allows the oil to pass through the compression circuit under minimal force. That means, that for the rider - There is far less force required to initiate the travel in a Fit4 fork, vs an older generation Fit CTD or Fit RLC. So with that in mind, it takes less of a impact from either the rider (pre-loading the front end), or from the ground to have the fork working and tracking the ground nicely. Secondly, by using a lighter weight oil (5WT R3) than previous Fit dampers, the Fit4 is by far the most sensitive Fox damper i’ve ever ridden.
So with all that sensitivity in the initial stroke, There’s still plenty of support throughout the middle section of the stroke and that remains consistent towards the end thanks to the cleverly designed bladder system that actually ‘sucks in’ on full extension, and ‘balloons’ out under full compression. Unlike the CTD or RLC Fit dampers, the cartridge bladder is heavily ‘sucked in’ whilst in the neutral (extended) position for a Fit4. That allows for the bladder to assist oil flow right from the start of the stroke, to the end - and back. (rebound).
See the Video of Chris’s Fit4 equipped Fox fork. Note the sensitivity!
See more of that here:
To compliment the lighter compression rate and lighter weight oil, the Fit4 also features a completely redesigned super low friction seal head at the rebound end of the damper, assisting the damper to be un-compromised in it’s full range of travel through compression and rebound. A slightly revised rebound piston is probably the closest thing left of a CTD damper inside the Fit4.
The External adjusters are same same, but different than the CTD. :) The Fit4 performance series damper is simply Open-Medium-Firm, with rebound at the base. The Factory series damper features the ‘open-mode-adjust’, with the same three settings as above, but with the ability to fine tune the open mode with a whopping 20 clicks of low speed compression adjustment! That allows riders to personalise how they want the fork to ride in open mode, and is probably much more utilised in open mode, than in previous generations where it was limited to 3 (2014 model CTDa) or 7 (2015 model CTDa) settings of ‘Trail mode adjust’. (The middle setting for those not familiar with CTD.
Our test bikes have included the Niner One9 RDO, Yeti ARC Carbon, and most recently - The Yeti SB45. All bikes have been fitted and tested with the fit4 at some point and the performance is amazing. Only a Rockshox charger damper comes close to the sensitivity of the Fit4, and the fact that the Fit4 damper is retro-fittable to older models 32, 34, and 36 - That’s a huge win for Fox fork owners.
Servicing of the Fit 4 is no more complicated than the previous Fit dampers, and when it comes time for it’s first full service, The genuine Fox service kits include all new seals, new seal head and a fresh new bladder.