FSA K Force Light MTB 2×9 review

Featherlight carbon mountain bike cranks

Our rating 
4.5 out of 5 star rating 4.5
GBP £500.00 RRP | USD $799.99
FSA K-Force Light MTB 2x9

Our review

Excellent performance and durability justify the price tag
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Sometimes there’s one product in a category that just kicks ass in about every relevant way you can think of. You’re paying a huge price for the privilege, but when it’s all about performance, nothing comes close to FSA’s K Force Light mountain bike cranks.


Even in triple form, these are among the lightest cranks you can buy, and the twin-ring 2×9 version we’re testing here drops below 700g, saving another 60g. Despite the low weight, the hollow carbon arms and chromoly steel axle are seriously stiff, with no hint of wasted power delivery.

‘Semi solid’ CNC-machined backside chainrings take that impressive stiffness right to the outer edge, and the Austrian AMAG 7075 T6 alloy has been remarkably tough and wear-free so far.

Ring stiffness combined with well placed pins and ramps ensures little shifting lag compared with a triple chainring, and the 44/29 split means less gear duplication. The lowest ratios are enough for any fit rider, and a higher chainline reduces the squish effect on full-suspension bikes.

Ceramic bearings are a big part of the complete chainset cost (£160 separately), but they run discernibly smoother and definitely longer than other original-equipment external bottom bracket units we’ve tried. 

Unlike other units, the bearings (rather the whole sealed cup units) are also fully user-replaceable, which means better long-term value. In fact, all elements of long-term life with the K Force have proved excellent so far.

A nice touch is the T30 Torx head in the chainring bolts which vastly reducing the chances of stripping, though they do mean a trip to the tool shop.

The new gloss black and red finish for 2009 (£500) promises more bling and longer-lasting looks. That way, at least everyone will know you’re mad enough to pay the price for the ultimate crankset.


They are cosmetically and crash fragile though, so don’t go mental with them. These are reassuringly expensive, incredibly light and stiff elite race cranks, but be careful with it off well groomed courses

Product Specifications


Name K Force Light MTB 2X9
Brand FSA

Description Options - 44/32/22 triple, 44/29 double
Weight (g) 720
Features Intergrated Mega Exo BB. Oversized
Colour Black
Material Carbon
Crank Arm Lengths 170mm 175mm