TESTED: FSA Afterburner i27 MTB Disc Wheel Set

You have probably heard it a lot, but one of the best upgrades you can make on your bike is putting a better set of wheels on it. Let's be a little more accurate and say, a better set of wheels that suits your bike and your riding. 

These 29" wheels have alloy rims, with an asymmetric rim for more even spoke tension. The straight pull spokes join to the hubs that use cartridge bearings, and a 6-pawl freehub on a 54t drive ring for rapid engagement. You can get the wheels with a SRAM XD, HG or Microspline freehub, as shown here. The rim width is in the product name, 27mm. This walks the line between 25mm and 30mm, but in doing so it also holds off the extra weight that a 30mm rim, in alloy, can bring. As such, our set weighs 1854g, which is pretty good for a set of wheels that could end up on an XC bike, downcountry bike or even a fast and light trail bike. It's not uncommon for stock wheels on mid to high spec XC bikes to weigh around 2kg with a 23mm internal rim. Plenty of trail bikes from the past few years would be the same, potentially with 2-2.3kg wheels with fairly basic spokes and hubs and narrow rims. As such, the FSA Afterburner i27 wheels may be a smart upgrade for those who want the benefits of a wider rim, less rotating weight and a fantastic set of hubs – while not trying to fit a wheel and tyre combination into a frame that just doesn't want to accept the girth!

Initial setup

The rims come without the tubeless tape or valves fitted, which is a great opportunity to see how well the rims are finished on the inside. It's a very smooth rim well, which typically helps the tyres pop up when they are inflated. The tape is high quality and went on nicely with some tension applied – if you're not confident doing this and creating a neat hole for the valve, just ask the FSA dealer you're buying the wheels from to assist with the setup. Check out our first look for more details. 

At 27mm internal, the wheels will suit tyre widths of around 2.2-2.4". I planned to fit these wheels to the Trek Fuel EX long term test bike, so I grabbed a set of Pirelli Enduro Hardwall 2.4" that Hayden had been testing when comparing Pirelli Scorpion Enduro sidewalls, and mounted them up to test the wheels. They inflated easily with a track pump and some Joe's NoFlats Elite sealant.

The straight-pull hubs use a 6-bolt rotor fitment, so I moved the stock rotors from the Bontrager wheels across, along with the Shimano XT cassette. It's worth noting that the hub is very easy to take apart, and I quickly opened it up before fitting the cassette, and was reassured to see plenty of nice and clean grease on the 6 hub pawls and drive ring. This should be easy for most riders to stay on top of as preventative maintenance.

On the trail 

When I had pulled the wheels out of the box, I was impressed with how smoothly the hubs spun. And while the 54t drive ring has a nice and fast engagement, I really think it is worth considering where the balance point of smooth rolling and engagement is. At a hair under $1000, I think the FSA wheels find the perfect balance, and they are one of the better rolling wheels I have ridden.

Taking off out of the driveway, the wheels felt as solid as what I had replaced, but with a little more pop from acceleration given the wheel system change dropped about 500g from what had been on the bike. On the dirt, the wheels hummed along as expected. and on singletrack climbs to gain the descents, I appreciated the fast engagement. Yes, there are faster engaging hubs out there with less than 6 degrees of movement for engagement, but they will normally come at a very high price, and there are some suggestions that more points of engagement can play a role in more pedal kickback in some suspension systems. Just something to think about!

With the 2.4" tyres fitted, I found the size they inflated to to be spot on. Yeah, they would have a slightly larger body if they were fitted to a wider rim. But as it was on the 27mm internal, the edge knob sat proud from the sidewall, which doesn't always happen on 30mm rims and all tyres. Given it's been so dry on my local trails for months, I actually liked the more pronounced edge knobs and the lighter weight, finding some great handling traits on looser trails that had plenty of sections erring to off-camber.

While I have spoken to the weight of the wheels, that's not to call them 'light weight' in a fragile sense. They are designed for trail use, and even using them in a local fun enduro (a Rocky Trail Superflow event) which has more rocks appearing from the dust every run, the rims are A1. They are a high quality product that excelled during the approximately 2 months use I gave them. But if you are one to ding rims a lot – you either need to fit heavier casing tyres, run higher tyre pressures, fit an insert or maybe all three. Optimise the wheel system, your riding and wallet will thank you in the long run. And any ride buddies who have to listen to your whinging or wait while you fix a flat!

Our take

Here at AMB we get to review a lot of wheels, and a lot of them are high zoot carbon wheels that cost more than plenty of very nice bikes. But let me be clear – a wheel upgrade does not need to be to a carbon wheel set with boutique hubs to be worthwhile. It just needs to be an upgrade from what you have, improving on what you don't like with your current wheels. And if that's material – go and spoil yourself. From experience testing a whole lot of bikes, a lot of very good bikes come with wheels more basic than they should. From rim quality, to hub and spoke quality and of course overall weight. Heavy, stock wheels can still have soft rims and may have a poor build quality, hampering not just the ride feel of your bike, but your time on the trails as well.

If you're looking for a greater rim width than stock, and you aren't likely to need tyres wider than 2.4", then the FSA Afterburner i27 is a very well-built, fast rolling wheel to look at. It would be an ideal way to drop weight from anything from some stock hardtails I have ridden, through to top XC bikes we have tested and some fast trail bikes as well. Think about what you want in a new set of wheels, and if the FSA wheels tick some boxes, then they will be a great choice.

RRP: $999.95
From: Advance Traders

Hits:

• Amazing set of hubs
• Great build quality
• Perfect upgrade for a lot of stock bikes 

Misses:

• Some may want wider or lighter