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First Look: FSA Launches New Off Road Carbon & Alloy K-Force, SLK, and Afterburner Wheelsets

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FSA K-Force Wheels_0

While better known for its cranks and finishing kit, FSA has recently enjoyed great success with it’s high end Vision road wheels. Ridden by the likes of Peter Sagan in the TdF, and to even more impressive heights by famed trials rider Martyn Ashton, FSA felt they could leverage that technology to create a feature rich off-road product.

They have divided the product line into three distinct models, which are versatile enough to encompass several dissimilar but related cycling disciplines – everything from gravel, CX, to XC and trail.

FSA K-Force Wheels_1

All three wheel sets share an offset asymmetric rim design. Many companies have experimented with asymmetric rims, but FSA has taken the design one step further. Rather than the more common 2mm offset, they’ve used a 4mm. The main benefit of this deign is improved spoke tension balance.

On regular rims, the spokes on one side of the wheels are always providing more tension than the other. With an asymmetric offset there is better triangulation of the spokes, which narrows the difference between the spoke tensions, and allows the wheels to brought to a higher tension overall. This offers increased lateral stiffness, rigidity, and durability.

As an added side benefit, FSA has also found they can run fewer spokes for decreased weight without sacrificing performance. So rather than your standard 32 h setup, these wheels utilize 24 spokes front and rear.

FSA K-Force Wheels_2

Each wheel set utilizes FSA hubs, with direct pull spokes. Aftermarket wheel sets will ship with various end caps, in order to make the wheel sets compatible with QR, 100×15, 135×9, and 142×12.

FSA 6 Pawl Hub Internal

Inside, the hubs have six pawls working in conjunction with a 27 tooth ratchet ring. As the free hub spins, three of the pawls are always engaged. This arrangement is durable and offers quick engagement (54 POE or 6.6 degrees of engagement).

FSA Afterburner WHeels0

The top of the line K-Force wheels receive ceramic bearings, while the carbon SLK wheels, and alloy Afterburner wheelset both spin on stainless steel bearings.


A preload system, borrowed for their Vision road wheels, allows you to adjust the bearings for improved bearing life and a faster spinning wheel. FSA claims this is an important feature because regardless of manufacturer, being able to adjust for small tolerance variations offers better bearing  performance – which equates to free speed.


All of the wheels are 100% hand built (lacing, truing, tensioning, etc.. ).

FSA K-Force, SLK, Afterburner Wheel Weights, Price, Etc

The K-Force and SLK wheel sets share the same carbon rim, which has a 26mm external, and a 21 mm internal measurement, but utilize different bearings, spokes, and nipples. The difference between the two is $250 and 36 g. 

FSA Afterburner WHeels1

On the budget side, the Afterburner rims share the same rim profile, but utilize aluminum hoops. Retail will be $649.99. The wheel sets will begin shipping on OE bikes beginning Q1 next year, and will be available soon after through distributors and IBDs.


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Von Kruiser
Von Kruiser
9 years ago

Must be stiff for a MTB wheel to run 24h. Will check them out at Interbike dirt demo to see how they ride. Always interested in checking out good trail wheels. Guessing they will come in 275 and 29er?

Mike Lawless
9 years ago

Yes, all of the new FSA Dirt Wheels (K-Force, SL-K and Afterburner) are available in both 27.5″ and 29″ platforms. FSA will be in booth number D2038 at Interbike’s Dirt Demo and we will have each model ready to test ride!

9 years ago

Internal width?

9 years ago

What’s 135×9? Do you mean 135×10? 135xQR?

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