Cannondale has always been known for doing things differently, and their top-tier cross country hardtail is certainly no exception. The clue is in the name, as FSi stands for Flash System integration, meaning all the parts of the bike work in sync with one another. This is Cannondale’s attempt to make a bike which meets the demands of modern cross country racing, featuring super short (429mm) chainstays and stable handling.
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Cannondale has achieved this by pushing the chainrings out by 6mm to stop the front mech hitting the tyre. To avoid this affecting the chainline, Cannondale has adjusted the dropouts so that the rear hub also sits 6mm to the right. The final piece in the puzzle is to spec a wheel with a different spoke offset, putting the rim back towards the centre of the frame. It may sound complicated, but it basically means you get a stiffer rear end, whilst still having the option to run a front mech.
Cannondale’s own Lefty fork has also seen some changes with a custom offset of 55mm, which, coupled with a relatively slack (for a WC XC bike) 69.8-degree head angle, should provide for more predictable handling when things begin to get steep and tough.
Even before we turned a pedal in anger, the FSi made its intentions very clear — for a £3,499 bike at 9.84kg this thing is seriously light, no doubt thanks to the Lefty fork and the carbon rims.
Once out on the trail, this feathery weight translates into rapid acceleration, with a real feeling of speed and efficiency. We were worried the 9mm QR back-end could result in some loss of stiffness, but the 429mm chainstays and neutral dish on the rear wheel ensure none of your expended energy is going to waste. This made a huge difference on steep climbs where the short rear-end helped maintain traction.
The Lefty fork certainly looks a little strange compared with what we’re used to, but in this short travel 100mm guise it works well, with serious fore and aft stiffness, and great small bump sensitivity. It comes with a hydraulic lockout, but we found the fully locked out setting lacked a touch of finesse, being very firm. We’d have liked to have seen a tiny bit more damping, but that’s nit picking and, overall, it’s a great package.
The bike takes a huge leap in performance when you hit the descents as the slacker head angle and custom offset Lefty create solid and predictable handling, without that usual feeling of "oh god I could go over the bars at any moment" found on old cross country bikes. This does make the steering slightly slower on tight switchback climbs, but it’s very minor and we wouldn’t exactly consider it to be a deal breaker.
The FSi comes with a narrow 27.2mm SAVE2 seatpost, which helps take some of the buzz and discomfort out of the trail.
One-by drivetrain’s are almost ubiquitous on XC bikes, so the presence of the SRAM X0 groupset comes as no surprise. It’s been around for quite a while and provides very reliable, lightweight shifting, without being too expensive to maintain. Cannondale’s Hollowgram SI cranks are the icing on the cake, feeling much stiffer than the SRAM equivalent.
The FSi isn’t without its faults though. The 2.1 Schwalbe Racing Ralph tyres (which come as spec) are too narrow, so it’s crying out for an upgrade to wider rubber. We also encountered some trouble setting up the front Magura brake with the SRAM shifter, as the shifter simply seemed too far away from our thumb when the levers were set up correctly.
Finally, it’s important to consider the compatibility issues which arise with the FSi, as all those proprietary parts mean you cannot conveniently use your old wheels or forks, if you do happen to have a spare bike. This may not be a problem for some, but many passionate cross country racers will know just how hard a season of racing can be, so having the option of reusing old parts can be a genuine lifesaver (or, at least, a bikesaver).
What we didn’t expect was how much fun this bike can be. Most cross country bikes of old were fast, but suffered badly from boring, uninspiring handling. What Cannondale has done is design a bike that’s incredibly fast, but meets the demands of the modern cross country racer with both stable and playful handling to help conquer the increasingly technical courses.
So, if your pockets are deep enough to meet the expense, and you don’t have a problem with being tied to using proprietary parts, then Cannondale’s FSi comes highly recommended.
This article was originally published in What Mountain Bike magazine.