Industry Nine (i9) earned its reputation by creating bulletproof, beautiful billet aluminum components in Asheville, N.C. Its mountain bike hubs earned an envious position as a top choice for riders building high-end custom wheelsets. The Solix SL AR40c partners the familiar i9 hub design ethos with its own new, modern carbon all-road rims.
I tested the Industry Nine Solix SL AR40c wheels for 10 months on a gravel bike that I used when there was a substantial amount of pavement on the planned route. In my area, rough, blown-out chip seal roads barely big enough for two lanes connect sections of hard-packed caliche byways. The average speed of these rides was on the fast side of my multisurface jaunts.

In short: The Industry Nine Solix SL AR40c all-road wheelset proved to be a high-performance choice for cyclists who want to go fast on both tarmac and dirt roads. It heavily skewed toward the fast and efficient side of the scale versus the adventurous and comfortable end. The Solix wheels are an ideal choice for gravel racing, and the hubs backed up the i9’s reputation for creating bulletproof but attractive products.
Looking for a new gravel rig? Check out our guide on the best current gravel bikes.
- Rim material: Carbon
- Rim internal width: 25 mm
- Rim depth: 40 mm
- Tire compatibility: 30-55 mm
- Rim diameters available: 700c
- Spoke material: Steel
- Spoke count: 24 front and rear
- Set weight: 1,430g (660 front, 770 rear)
Pros
- Fast and efficient feel
- Industry Nine's reputation for durable, serviceable hubs
- Light for the rim depth
- 12 available anodized colors for hubs and spoke nipples
Cons
- Straight-pull, direct thread spokes might be hard to find
- Not as comfortable as more adventure-oriented gravel wheels
Industry Nine Solix SL AR40c Review
The numbers on the Solix SL AR40c point toward gravel racing or fast all-road/gravel riding. Industry Nine offers this wheelset in 700c only, and the MSRP is $2,330.
Those i9 Solix SL Hubs

It doesn’t do justice to not focus a bit on the Solix SL hubs, as Industry Nine has forged a rock-solid reputation for producing some of the best.
The aesthetics of the Solix SL hubs are hard to overlook. The straight-pull hub shells are immaculately milled and finished, and i9 offers them in 12 colors. Customers can also specify the color of the spoke nipples.
The patented freehub mechanism uses five spring-loaded pawls to mate with a 121-tooth drive ring. This produces an incredible 605 points of engagement for a 0.59-degree engagement angle. Of all the hub specs, this group of numbers is the most impressive.
The billet aluminum hub shells have a deeply scalloped, minimalist-looking body, which Industry Nine claims maintains strength while shaving weight. The bearings are the same size on the drive and non-drive side, which isn’t always the case. i9 claims this equalizes the load placed on the hub shells. Additionally, the radial lip seals on these bearings are user-replaceable.
The Industry Nine Solix SL hub’s direct-thread holes are configured for CX-Ray bladed spokes laced in a two-cross pattern. i9 only offers the Solix SL hub with Center Lock brake rotor mounts.
AR40 Carbon Rims
To go along with the new Solix SL hub, the brand laced it to a new AR40 carbon rim. From the outside, the i9 rim looks like many mid-deep aero road rims. But the AR40 rim does have one feature that is becoming less common — a hooked sidewall that is a stout 4mm thick.
The brand states that the hooked rim allows higher air pressures without increasing the odds of tire blow-off, and the thick bead area protects the tire better against pinch flats by spreading impact forces. Industry Nine states that the layup is purposefully robust to better match the potential abuse of gravel riding.
As is the trend, gravel wheelsets are increasingly focused on aerodynamic efficiency. And i9 used Computational Fluid Dynamics (CFD) and claims that the rim profile was chosen to fend off the effects of crosswinds while still being aerodynamically efficient for tires up to 42mm wide.
Riding the Industry Nine Solix SL 40c Wheelset

The Industry Nine Solix SL AR40c wheels felt efficient right away. It wasn’t subtle; it was obvious that this wheelset i9 aimed the wheels at gravel racing or high-performance riding.
Solix SL Hub Performance
The first thing I felt was the freehub’s incredibly quick engagement. The tiniest forward pedaling motion locked the rear hub into drive mode. I never felt any “spooling up” or hesitation, and the engagement didn’t produce any noticeable feedback. It instantly, smoothly, and quietly turned chain tension into forward drive — and this sensation was in comparison to some of the most expensive wheels on the planet.
Industry Nine hubs have a widespread reputation for producing the sweetest free-coasting sound. Indeed, the sound of that freehub when I stopped pedaling was such a delight (to a total bike dork) that I found myself sacrificing forward momentum just to listen to it closely.
Handling
The rims delivered a similar racy vibe as the hubs. The AR40c rims felt very stiff laterally compared to other gravel-oriented wheels. This also meant they weren’t as vertically compliant as the more adventure-oriented wheels I was concurrently riding. They definitely felt built for speed over providing comfort.
I opted to max out the tire width at 42mm and run lower pressures to combat the vertical stiffness of the carbon rims. This was the sweet spot for me for the typical longer rides I do around my home.
Loops of hard-packed and rock-strewn gravel linked together by rough and poorly-maintained chip seal roads. The Solix SL 40c wheels with the 42 mm wide tires, inflated to the high 20s, felt fast and efficient enough on the roads while still giving me enough bump compliance and traction in the dirt.
The wheels’ lateral stoutness paid off big time in the handling department. The Industry Nine Solix SL AR40c wheels made carving the gaps between embedded rocks feel telepathic. When I had to slow down to pick my way through basketball-sized rocks, the torsional stiffness was appreciated; I never had that unnerving feeling that I had to exaggerate steering inputs to compensate for a front hub twisting within the wheel.
These wheels are not for touring or cruising. They are best suited for those who have segment goals on Strava and understand that a level of stiffness in the wheels is necessary to deliver an efficient and fast feel. The wheelset’s claimed weight of 1,430 g reinforces the need for speed ethos.
Durability
I treated the Industry Nine Solix SL AR40c wheels like any wheelset targeted toward dirt: poorly. I never washed them, even when they had a thick coat of dust on them, and I couldn’t tell what color the hubs were. But I did let torrential rain do that for me. Although i9 labels them as all-road wheels, a significant portion of my local gravel roads easily qualify as rough gravel territory.
The axles spun more smoothly and freely between my fingers than when I unboxed the wheels. Credit the end cap-mounted proximity seal and radial contact seal on the ABEC 5 Enduro bearings for keeping the bearings clean.
Should you need to service anything, the Solix SL hubs use common assembly; swapping the readily available bearings can be done with a standard bearing press. The only thing that I considered “non-standard” was the direct-thread spokes, which aren’t as available as J-bend spokes.
Industry Nine built a well-deserved reputation for durability and serviceability with its mountain bike hubs, and I strongly suspect the Solix SL hubs will be the same.
The wheels spun as true after 10 months of riding as the day I first mounted tires. A lifetime warranty covers the rims against defects and impact damage.
Conclusions: i9 Solix SL AR40c Gravel/All-Road Wheelset

Gravel racing and high-performance riding are having a moment. Some lament that the adventuresome “spirit of gravel” seems to be dying a slow death. Humans seem unable to resist racing or pushing personal performance.
This was my go-to wheelset for the entire testing period when any significant amount of road miles was on the menu. I appreciated the fast and efficient feel while trying to beat encroaching darkness or heat. The instant engagement of the freehub added to the feeling that I was spinning wheels crafted to break personal bests.
The wheels also felt like products of fine and meticulous craftsmanship, and knowing i9 fabricated them in the trail town of Asheville was a welcome bonus.
The price is steep but in the ballpark of other premium carbon wheelsets made in the U.S. However, owners can take comfort in the fact that the hubs are serviceable, the bearings are common, and every other part is replaceable. And, Industry Nine backs its carbon rim with a lifetime warranty.
If you look at Strava segment standings and curse the rider that constantly steals your KOM, the Industry Nine Solix SL AR40c all-road wheelset is worth consideration.