First impressions: FSA KFX i28 gains trail feel not weight

FSA is revamping its cross country KFX wheels, moving to wider, but not necessarily wide rim. FSA KFX i28 also creates a new rim profile for the lightweight carbon fibre hoops. Together, that makes a reasonably major change for the brand’s top XC wheelset.

FSA KFX i28: What’s new

One major change to the KFX line is right in the name. Instead of a 25mm internal width, the KFX are n0w 28mm internal (33m external rim width). While a lot of rim manufacturers are at 30mm internal for XC race rims, FSA isn’t getting caught up in the trends and sticking with a wider, but not wide rim width. That should still support up to 2.4″ tires that some XC racers are running comfortably. FSA claims this width provides the best balance of lighter weight, stability and traction, the latter of which which we’ll get into a bit more below.

The second major change is to the rim profile. FSA uses a variable height for the carbon fibre rim. Compared to the consistent 30mm rim depth on the old KFX i25, the new KFX i28 is 22mm but with 24mm deep sections rising up to meet each spoke. That’s considerably slimmer, with FSA joining the movement to rims that use some flexibility, tuned to specific ride qualities, and not just designed to be as stiff as possible.

The rims are still hand built. They’re now laced to a PRS x-900 hub. The new hub uses a 72-tooth ratchet mechanism for quick engagement. Other details on the KFX i28 include a continuation of the 24-count direct pull spokes with brass spoke nipples, an offset asymmetric rim design that aims to keep more consistent spoke tension, and a 1,556-gram weight (without rim tape or valves). FSA does move to six-bolt disc brake mounts. The new rims are compatible with XD or Microspline freehubs.

Liftime warranty backed by extensive testing

FSA says it’s performed significant strength, fatigue and weather testing on the KFX i28 rims so, while the new design is still quite light and has a totally new shape, the brand is quite confident its durable for enough for XCO and marathon racing, and even beyond. FSA says the rims were tested to over twice the 40 Joule industry-standard impact test, as well as fatigue tests – which were performed both with the wheel vertical and at an angle to better mimic real-world stresses.

Given all that testing, FSA is backing the KFX i28 with a lifetime warranty.

FSA is offering the KFX i28 for a suggested price of  USD 1,810.00 (EU €1,900.00). That’s not exactly cheap, but FSA is clearly aiming for a rim that can reach the top of the podium (The FSA-sponsored Cannondale Factory Racing’s Alan Hatherly repeatedly has this season) and thrive under everyday riding.

First impressions: FSA KFX i28

I’ve had a few weeks on the KFX wheels at this point and are impressed with how they feel on the trails.

The KFX feel quick to spin up to speed, even climbing out of repeated switchback corners. They’re not, at 1,556g as light as some more radical (and more expensive) designs out there. But FSA also thinks they’re tougher, pushing well into “downcountry” (or just everyday riding) and edging towards trail riding while still at a competitive weight. I started with a very XC set up (Maxxis Aspen ST rear and Ikon front) to compare them to some other fast wheels. This is their primary purpose and they excel at that. Putting tougher tires on showed that, while they’d be great for racing, this isn’t just a race-only wheelset.

There is a nice ride feel to the KFX i28s. They don’t feel super harsh, but they also don’t feel vague at all. The new rim shape is quite different than FSA’s prior design and it seems to pay off. More brands are experimenting with compliance, letting rims move a little to reduce fatigue or to find more traction. The KFX i28 join this party. And, for what its worth, the PRS X-900 hub is comfortably quiet while coasting, thank you very much.

All in, the KFX i28 feel like a very balanced wheel. The rim profile helps FSA make the rims wider than the last generation without adding weight. At the same time, it feels like there’s more consideration for ride quality over just pure power transfer.

The post First impressions: FSA KFX i28 gains trail feel not weight appeared first on Canadian Cycling Magazine.