What's Cool In Road Cycling

AmClassic 420 Aero Disc Wheels Review

The fashion for the uphill finish is still strong, but the recent trend in sections of gravel roads is catching on: The Strade Bianche and stage 1 of Paris-Nice in the last weeks. So if you are thinking of putting a gravel bike together, Jayson O’Mahoney has been putting a set of American Classic 420 Aero Disc Tubeless wheels to the test, here are his findings:

-Photos and article by Jayson O’Mahoney-

American Classic Wheels are virtually a household name in the bicycle industry. Founded in 1982 by engineer, innovator and former bicycle racer Bill Shook (read an excellent interview here), the company has long been associated with innovative products that are on the cutting edge of design.  Originally confined to the production of seatposts and bottle cages, the company expanded their product range to become a leader in bicycle wheel design and production, and unlike many of their competitors, American Classic own their factory and produce only wheels for themselves.


Unless you’re remiss from keeping up with the latest wheel design trends, bicycle rims and tires have become wider for both mountain and road bikes. Wider rims make it possible to ride lighter and smaller performance oriented tires with plenty of volume, which translates to a cushier ride and an increase in tire width beyond its stated casing size. The tire casing stretches out across the wider rim; that 700c x 23mm tire you installed now becomes a 700c x 25mm tire or wider, depending on rim width.

Then there is the tubeless factor. Virtually a standard in the world of mountain biking, road tubeless has been around for approximately 10 years.  While road tubeless hasn’t been widely adopted by riders, American Classic were early adopters and now offer their entire road wheel line-up as tubeless ready.  Of course you can still run standard issue tubes and tires on all their rims, but the benefits offered by going tubeless (lower weights and self-sealing tires) are something AC believes we’ll all be wanting in the near future.

But this review isn’t about the negatives or positives of tubeless technology. Rather, we examine the American Classic 420 Aero Disc Tubeless wheelset – a road / gravel bike wheelset – intended for disc brakes. Still a relatively new development in the genre of road cycling, disc brakes are old news on mountain bikes. When disc brakes first began appearing on mountain bikes, there was resistance to adoption of the technology. Now, there is not a single new mountain bike available with cantilever or U-brakes. Love them or hate them, disc brakes are making in-roads to road bikes and virtually standard equipment on purpose-built gravel bikes.

Weights and Tech Specs
Out of the box, fitted with American Classic’s latest blue colored tubeless rim strips, the disc brake 420’s tip the scales at 802 grams front and 899 grams rear. Manufacturer’s specification is 788 grams front and 888 grams rear, meaning the wheels fall within the typical + / – 2% of advertised weights – 1701 grams for the pair.


Front and rear wheels are built with 24 spokes in a two cross pattern, with American Classic’s own bladed spokes and aluminum nipples completing the build.

Compared to the company’s lighter rim brake version of the same wheelset, additional weight is gained at the disc hubs and spokes; a beefier spoke configuration is required to handle increased braking torque. On the positive, the disc brake wheelset essentially shares the same rim as the rim brake version, so there is no additional weight penalty at the rim – rotating weight at the furthest point of the radius is the most important to keep down.

(The black steel inserts prevent the cassette from biting into, and damaging the aluminum cassette body).

The hubs at the center of the 420 Aero Disc Tubeless wheelset are well thought out. Designed for optimal flexibility, the hubs can easily be converted between all of the current axle standards – standard quick release – thru axle in the front for 12mm / 15mm – thru axle in the rear for 12mm x 142mm. Likewise, the cassette body can be swapped between Shimano / SRAM 10 / 11, Campagnolo 10 / 11 and SRAM XD. Hubs utilize the center lock disc brake standard and tip the scales at 130 grams for the front, 225 grams for the rear.


Completing the package is American Classic’s excellent valve cores – for those who plan to run the wheelset with tubeless tires – rotor lockrings, center lock -> 6 bolt disc rotor adapter and cromoly quick releases – assuming you ordered the wheels configured for them – and two cassette spacers. The silver spacer is for those using a 10-speed cassette with the wheels while the thin black one is there just in case you need a little more clearance between the spokes and cassette.


The rims measure 34mm deep, 22mm outside edge to edge and 19mm wide inside. The 420 rim features a channel designed to lock a tubeless tire in place, but at the same time allowing a consumer to use a regular tube & tire combination. Available upgrades to the wheelset include ceramic bearings and American Classic wheelbags.

Rims are designed for both tubes & tubeless configuration.

Disc Rotor and Tire Installation
The 420 Aero Disc Tubeless wheelset accepts center lock rotors or the venerable 6-bolt standard with the provided adapters. I ran these with a set of in-house Avid 160mm 6-bolt rotors.

(Step 1 – Situate the rotor adapter in the appropriate position followed by the rotor on top).

If you notice carefully, the rotor adapter features a step-down at each of its mounting points. The step-down provides clearance for the rotor lockring when it is installed.

(Step 2 – Install the rotor lockring into the threaded portion of the hub. I like to apply a little grease to the threads first – then, using your fingers, grip the lockring and turn in a clockwise direction to tighten).

(Step 3 – Using a tool such as the Park Tool BBT-9 bottom bracket installation wrench, tighten the lockring to specification – American Classic recommends 40Nm. Obviously a torque wrench is optimal for this part of the installation, but use common sense to tighten, but not overtighten.


I have a lot of tubeless tire experience on both road and gravel bikes – but I didn’t want to focus on the tubeless tire aspect for this review. Since many consumers are still easing their way into road tubeless, I felt a regular tire and tube combination would serve best for the review. However, to put everyone’s mind at ease, I can tell you an IRC Pro Tubeless road tire in 25mm and a Maxxis Rambler gravel tire in 40mm both mounted and held air almost effortlessly on the 420 tubeless rim. In the case of the Rambler, a compressor was used to mount the tire.

For this review, I chose one of my favorite clincher tires, the Michelin Pro 4 Service Course. The tires were a little tricky to mount, but the process went much easier once the correct technique was used. Once the first side of the tire has been mounted onto the rim, it is important that the tire’s bead is situated in the center channel of the rim. This will make popping the other side of the tire onto the rim a much easier proposition. For the record, the same installation procedure applied to the IRC Pro Tubeless road tire I mentioned earlier.

The Ride
My ever reliable Calfee cross / gravel / road rig served as the testbike for this review. Because the Calfee was built at a time before the invention of thru axles, I used regular quick releases with the 420 wheelset.


Because the 420’s weigh in the 1700 gram range, they aren’t super snappy during acceleration. However, while they may take a little longer to windup to speed compared to some of American Classic’s lighter offerings (check out the Pez review of the Argent wheelset HERE), they require less pedalling effort to hold and maintain speeds at over 25mph. Because of the shallower rim profile of the wheelset, they are not intolerable in side and crosswind conditions, which can cause genuine handling and safety concerns for lighter riders.

The 420’s are stiff – while I am not a powerhouse rider and weigh about 157lbs, I was unable to noticeably flex the wheels during out of the saddle efforts. The wheels may have 24 spokes front and rear, but those spokes are bladed and torqued to a decently high tension.

I typically ride my road wheels with tires inflated to about 90psi, and this pressure was optimal for the 420’s on all but the bumpiest of roads. If I purposely took the bike and wheels onto hardpack gravel roads – and I did – I would drop the tire pressure to around 80psi front and rear – that definitely helped with the comfort factor. For tubeless tires, I would recommend dropping the tire pressure to 75psi – another advantage of tubeless – lower tire pressures, comfy ride and flat protection.

Because of the wide rim properties of the 420 wheelset, you effectively gain 2mm of free tire width when any tire is installed – tubeless or tubed – which gives an extra measure of cornering confidence knowing there is a little more rubber helping to maintain grip on the road. With that said, no issues during cornering on the 420’s.

As expected, this is an area the 420 wheelset shines. A top quality set of rim brake calipers can offer excellent braking performance and modulation, but inclement weather is where rim brake power can suffer.  In really wet conditions, rim brake pads can take longer to “bite” the rim and ultimately begin slowing the bike. Bad weather specific rim brake pads certainly help, but disc brakes outperform rims brakes when it comes to slowing down.

While there are two brake pad compounds available for most disc brake calipers (sintered and organic), with the latter having the best overall performance but worst wear qualities, the brake power offered, particularly if the disc caliper is hydraulic, simply blows away the braking power of a rim brake. This is especially evident if you were to compare equivalent hand effort required to achieve the same level of braking.

For the review, I was using my trusty TRP Spyre dual piston mechanical disc brakes. They definitely are not as powerful as a comparable Shimano R785 hydraulic brake caliper, but they are on par or better than the best rim brake calipers. But again, their disc brake power shines in bad weather.


During a rapido and somewhat technical descent with the 420’s on board, I was able to brake later and with more power as I setup my line going into a corner – that doesn’t have so much to do with the 420’s but the disc brakes and the rotors themselves. Descending can be a risky business, especially if you like to push the edge, but disc brakes provide another measure of confidence and safety.

Overall, the 420 Aero Disc Tubeless wheelset is a solid and reliable wheelset that is perfect for road, gravel or cyclocross use. The sheer versatility of this wheelset cannot be overlooked. With their easily convertible hubs, it is a simple matter of obtaining the appropriate axle kit from the American Classic website should you decide to upgrade your bike. And, they can run tubeless or with tubes.

The other thing I like about the wheelset is American Classic’s use of non-proprietary spokes. Sure the spokes are bladed, but they are regular J-bend spokes, and could easily be substituted with a round spoke from your local bike shop in the event of a breakage.

During the period of my review the 420’s remained as true as the day they were received, and sans any annoying ticking or clicking noises. Not the deepest of aero wheels, they rolled fast and cut the air nicely with their 24 bladed spokes at each wheel. I’m not an aerodynamics expert, but I believe disc rotors have only a small impact in the overall performance of a quality road bicycle.

I’m a firm believer of the placebo effect – reliable and fast equipment translates into a rider who is happy, and who rides stronger and longer – the 420 Aero Disc Tubeless wheelset certainly made me happy.

At $US 1049.00, the 420 Aero Disc Tubeless wheelset is very reasonably priced.

For more information on the American Classic 420 Aero Disc Tubeless wheelset and their entire range of wheels, visit their website: www.amclassic.com/en/.


• Jayson O’Mahoney also publishes as the Gravel Cyclist: a website about the gravel cycling experience.

Note: If you have other experiences with gear, or something to add, drop us a line. We don’t claim to know everything (we just imply it at times). Give us a pat on the back if you like the reviews, or a slap in the head if you feel the need!

PezCyclingNews and the author ask that you contact the manufacturers before using any products we test here. Only the manufacturer can provide accurate and complete information on proper use and or installation of products as well as any conditional information or product limits that may limit their use.

Send your comments to: [email protected]

Like PEZ? Why not subscribe to our weekly newsletter to receive updates and reminders on what's cool in road cycling?

Comments are closed.