First Look: 2019 Cannondale F-Si – skinnier, more comfortable and faster than before

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This week, whilst Britain was finally getting to enjoy some glorious spring weather, Cannondale launched the 2019 F-Si XC hardtail at the Albstadt World Cup in rather wetter and muddier conditions than at home.

Dusty trails not included

Given the pace of MTB geometry change over the last few years it’s easy to assume the previous F-Si, launched in 2015, would look a little outdated by now. But in reality the 69.5o head angle and 429mm chainstays of the outgoing model means it remains one of the most progressive XC hardtails out there. And so the question was, what would Cannondale change on the new model?

The answer is not much and an awful lot all at the same time.

You look kinda different. Have you lost some weight?

The biggest change is the new Lefty Ocho fork. This represents such a big change though that it deserves its own First Look piece which you can find here. On top of the smoother, stiffer and lighter 100mm fork, the front end geometry has had a few additional tweaks. The head angle has been taken out a further half a degree to 69o which combined with the 55mm fork trail results in 84mm trail and 691mm front centre measurements making it longer and more stable than before (and longer than its competitors), but with a short trail to keep the slow speed handling nice and tight. Combined with the specced 760mm bar this is an XC bike designed for some aggressive handling.

Svelte and wide all at the same time

In comparison to changes at the front end, all the other updates are rather modest. At the back Cannondale keep with the AI (Asymmetric Integration) system which was first seen on the F-Si and now features on the Scalpel, Trigger and Jekkyl too. AI moves the transmission 6mm outbound compared to a standard rear end (and another 3mm more than a Boost rear end). This allows for short chainstays, lots of clearance for a 2.35in tyre and mud too, keeps the option for a front mech and maintains the Q-factor of the cranks. The trouble is you need specific cranks and a rear wheel for it, although as there’s less dish on the rear wheel it has the added benefit of being stronger than a standard wheel. In comparison to the previous F-Si, the chainstays have been shortened down by another 2mm to 427mm for that little bit more power transfer and traction to the rear wheel and greater manoeuvrability in the tight turns too.

Checking the mud clearance will cope with the UK

Another couple of changes are to improve the comfort of the bike and its traction on the rougher stuff. Firstly there’s a very neat integrated seat clamp, which allows for a longer seat post to be run which in turn gives more flex and therefore comfort. There’s routing if you want to fit a dropper although with a 27.2mm diameter your options are limited. For the Cannondale designers, this was a deliberate decision as whilst they know it’s a bike that is capable of bigger riding where people will want to run a dropper, they also wanted to keep its focus as a lightweight race machine so have prioritised the comfort of a skinny post.

Neat and tidy clamp and long seat post

The other design feature to improve comfort are the mega thin seatstays that have been designed to maximise vertical compliance to give more shock absorption and therefore comfort in the rear end, particularly when standing. On the flip side, the diameters of the down tube and top tube increase as frame sizes do to maintain the stiffness as the tubes lengthen with the bigger sizes.

Short stiff chainstays and skinny seatstays

The final tweak is that frame weight has decreased by a further 80g for the top end HiMod frame, which at 900g puts it close to the Scott Scale RC 900 (849g) and the Specialized S-WORKS Epic (890g). As a full bike combined with the Lefty, Cannondale maintains that the top end bike is the lightest available at 8.4kg (18.5lbs) although these weights are unverified on the Singletrack Scales of Truth. At the other end of the range the Carbon 5 is claimed to be less than 11kg so still nice and light.

Not the launch weekend weather

The F-Si will be available in the next few weeks in  frame sizes XS, S, M, L and XL. Wheel size is 29in except on the extra small where its a proportional 27.5in. There will be seven different bikes available (all with carbon frames) with the World Cup build with DT Swiss hubs, ENVE rims, and SRAM XX1 transmission topping the range. The Carbon 5 model with a RockShox Reba fork rather than a Lefty will be available a bit later this summer and further into the future the F-Si will be available as frame only. Pricing will be as following:

29 F-Si Hi-MOD World Cup £ 6,999
29 F-Si Hi-MOD Carbon 1 £ 5,499
29/27.5 F-Si Carbon 2 £ 3,999
29 F-Si Carbon 3 £ 2,999
29 F-Si Carbon 4 (and W 2) £ 2,699
29 F-Si Carbon 5 £ 1,899


For first ride impressions of the F-Si and Lefty Ocho, follow us over to here.


Rachel’s travel and accommodation to Albstadt were paid for by Cannondale.

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