FSA (Full Speed Ahead) just keeps on adding to the things they offer the cycling consumer. Recently it was hydraulic brakes and before that, myriad options for cranks, BBs, etc. They are not standing still. Now we have wheels as well, and I have had a set of the Afterburner 29s in house for some months now. Let’s look at what they are, how I decided to run them, and why.
First of all, there are three levels of wheels in the cross country category: K-Force Light, SL-K, and Afterburner. If you are at all familiar with how FSA differentiates their product lines, seat posts, stems, etc, then you know that the top level stuff is K-Force Light, SL-K then Afterburner. With K-Force Light ($2049.00@1464g)) you get carbon rims AND ceramic bearings and with SL-K (1799.00@1500g) you just get carbon rims. Afterburner, MSRP of $649.99 and a claimed 1660g a pair, are an all alloy build.
They share the same hubs, spokes differ a bit from model to model, but the rims have the same offset shape and dimensions, only carbon in some cases, as I called out.
When I was talking to Mike Lawless, marketing wizard at FSA, he pointed out that these are not just MTB wheels, but are to be considered ‘Off Road Wheels’, crossing over into cyclocross and adventure road/gravel as well as classic MTB riding. This is an interesting pitch, and it makes sense when you look at what has been happening in the marketplace as a whole. With the advent of discs on road or gravel road bikes, often we are talking about 135mm wide rear hub spacing and even 142×12. Front hubs are often the same now across the board (not counting Boost, of course) in disc hubs, so a 15mm thru axle can fit many types of bikes out there now that thru axle forks are pretty common, especially on adventure/gravel bikes with disc brakes.
And these rims used in the new wheels across the FSA line are not that wide, internally. At a 21.5mm inside width, that is a bit out of step with the trend toward wider rims for trail and even XC riding. So what do we do with these? I had an idea. If they are pitched as being an ‘all-rounder’ wheel, let’s depart form the norm around here at twentynineinches.com and run them on a gravel bike. Yep. I have one of those things. Absolutely love it. When I built up my Salsa Warbird, I initially used a set of old 29er wheels (DT Swiss Spline 1) converted to an 11spd freehub and the proper end caps.
And when you think about it, a ‘classic’ non-wide 29er wheel is really perfect for an adventure/gravel bike. They are disc ready and typically convertible for axle configs, they are tubeless (most likely), and since most rims in the recent past were around 26mm wide (outside width), that means they were about 21mm internal, just perfect for a 35mm-40mm+ tire. And on top of that, since they were built tough enough to survive a 29er MTB, then they sure will handle a gravel bike’s abuse.
So when the FSA Afterburners came around, they were bang on for what I wanted in a gravel bike wheel, potentially shaving off some weight over the DT Swiss hoops.
The details from the FSA website –
Hand-built by experts and highly versatile, the tubeless-compatible Afterburner MTB 29” wheels are an ideal upgrade for fast mountain bikes, cyclocross and even gravel bikes. The six-bolt hubs take modern disc brake systems.
At 26.1mm wide and 25mm deep, the asymmetric aluminum rim is near-square and very strong. Black anodising gives a tough finish and – alongside black spokes and black brass nipples – lends the Afterburners a mean and stealthy look. They’re just 1660g a pair.
The front hub takes 9mm QR or 15mm thru-axles, and holds 24 straight-pull spokes in a two-cross pattern. The 24-spoke rear hub boasts a 6-pawl aluminum freehub for instant engagement, and runs on a double row of stainless steel bearings. It’s available for Shimano 9-11 speed or SRAM 11-speed, and compatible with 135mm QR and 142mm thru-axles.
Also included are alloy QR axles, sealant tape and tubeless valves.
I am not so sure I am a fan of low spoke count MTB 29er wheels, although the rim sure has a lot to do with balancing all that out, but on a XC bike or a gravel or cross bike, 24 spokes seem to be plenty. Looking at the cost VS. the weight, $649.00 and 1660g is very good. For instance, a set of Roval carbon wheels (not the SLs) are only 100g lighter and are twice the cost. However I found I did not come up with the weights claimed by FSA. I weighed them twice in a ‘bare’ condition, no tape, stems, etc, and found the front to be 816g and the rear 948g. That is 100g above the stated weight. I called FSA and they did not have any numbers to offer that cleared this up, so that part is a mystery.
As well there is a unique bearing preload system that is supposed to keep unneeded stress off of the hub bearings and a fast engaging hub for quick take up from coast to drive. Here is a video that shows all that and more.
On trail…errr, or road or dirt or whatever.
Out of the box, the wheels came with all the goodies to go tubeless, but I had some issues with applying the FSA tape. It did not call out how many wraps (two would be the ‘norm’) or, more importantly, whether to install the tape under tension or not. Turns out it is two wraps under some tension, but by then I had moved on to one wrap of Gorilla Tape. No biggy. The valve stems look like Stan’s valves, but they come with a cool little offset spacer that goes under the compression nut.
Spinning the freehub by hand gave me a fine-toothed “brrrrrrr” sound, not really like a DT Swiss or a King hub, but quieter and more refined, if a sound can be that. There is not much freehub rotation before it begins to drive. There is a sticker wrapped around the freehub body that looks like a death warning about using cassettes that are not on a spider or at least pinned together. I assume this is to keep the alloy freehub body from getting ‘notched’ from individual cogs like are typical in less than the highest of high end cassettes. For instance, I am running the SRAM Rival 22 drivetrain, but I swapped to a SRAM PG-1170 11-36 11 speed cassette and it only comes with separate cogs, at least for most of it. It is what it is. However, after many miles of use, I did pull it off with no trouble and only noticed a slight dimpling on the freehub splines, so I can live with that.
I did get a kick out of this sticker as well…silly lawyers. Just in case your rim brakes cause damage, I guess.
I mounted a set of Panaracer Gravel Kings in a 40c size and they set up with a floor pump and held air right away. The 21.5mm internal width gave the 40s a nice, full shape.
After a good many hours, both on pavement and dirt, over ruts and through bunny hops…under hard sprints and fast descents and even a race or two, the FSA Afterburners have been solid, light feeling and fast accelerating even though they have a moderate weight overall. Coming from the DT Swiss Spline 1 wheels, which were no slouch, the FSA Afterburners felt like they rolled out faster and moved forward better under hard efforts. The hub engages very quickly, if that is important to you. To me, it is nice, but not that big a deal. They are quiet as well and I do like that. I have hit them a few times pretty hard at angles, and with a lesser tire on there than a typical 2.2″ 29er might run, it does put more stress into the wheel. I have not had to true them or touch a thing.
The only thing that I have noticed to the negative is every so often, when going from coast to drive, I catch a pawl off guard and get a solid ‘PING’ as it heads for home. It has not gotten worse or better, and it does not always do it every ride. But there it is.
Overall, with the understated looks, the fast engagement and quiet freehub, decent weight, and a solid feel when pressing them hard, the FSA Afterburners are a good choice so far for this genre of bikes. I did not get them into bad weather or mud, so sealing in that sense is a unknown to me. At under $700.00, they are worth a good looking-into when it comes time to upgrade your anchor stocker-wheels without breaking the piggy bank. I do wish the weight would have been as claimed as that would have really set them apart for the cost. If you are looking at less weight, then the carbon SL-K versions would be a good middle ground between the chi-chi K-Force Lights and these wheels. I also wonder if carbon rims…although the profile and layup are the wild card here…if carbon allows less impact to be transmitted through what will certainly be a smaller tire volume under higher pressures on a gravel/adventure bike.
I will continue to run them on the Warbird until the next set of wheels comes along to review and if the long term results change my mind about them, we will let you know.
A typical So Cal view…foothills for miles and lots of dirt roads. A 50 mile day of mixed surface riding on the Salsa Warbird with the FSA Afterburner wheels.
Note: FSA provided this product at no charge to Twenty Nine Inches for test and review. We are not being paid, nor bribed for these reviews and we will strive to give our honest thoughts and opinions throughout.
