Industry Nine SOLiX SL 35c wheelset review: Highly engaging ride but missing marginal gains

While Industry Nine’s 1X1 and Torch already catered for drop bar riders, they didn’t offer the same ultra-snappy pickup as the legendary Hydra hubs. Industry Nine changed that with the release of the SOLix hubs last year, which are available as hubs only or as road, gravel and XC wheel builds. The hubs are equipped with almost the same instantaneous pick-up as the Hydra MTB hubs but packaged into a lighter-weight shell designed for faster riding. 

Despite being a hot topic in mountain biking, freehub engagement isn’t a subject that's often talked about on the road. Admittedly there’s a good reason why mountain bikers spend time stressing over POE. It has a dramatic effect on suspension performance and when your front wheel is teetering on the edge of a drop fast engagement can be the difference between riding a section of trail or literally falling head-first off a cliff. POE, for the uninitiated, stands for points of engagement, and the more you have, the faster your hub engages.

Instead, developers of the best road bike wheels are far more concerned about shedding weight and slicing through the air as efficiently as possible. I’m firmly in team high-POE when heading off-road, so I was excited to see how the rapid response freehub would translate to the road. 

Design and specifications

Other than some boutique outliers like Onyx, the SOLix hubs are the fastest engaging dedicated road and gravel hubs I know of. Using an ultra-fine 121-tooth driver ring, the five leaf-sprung pawls work in phases to give 605 points of engagement. This translates to just 0.59 degrees before the hub engages for an almost instantaneous pick-up when you start pedalling. 

To give you a comparison of just how fast that is, the ZR1 DB used in Zipp’s 303 Firecrest has an engagement rate of 5.45 degrees and Hunt’s Sprint hubs are 7.5 degrees. For those running DT Swiss hubs with the standard 36t ratchet, the 10 degree gap of rotation is frankly astronomical compared to the SOLix, even with the upgraded DT Swiss 54t ratchet they only manage to achieve a 6.66-degree engagement. 

While the thought of a full-effort sprint load focused on a single pawl might raise concerns about durability I've yet to have an issue of free hub skipping on the SOLix. The Hydras use a similar pawl system and having put plenty of miles on multiple sets of Hydra’s, they too have been faultless.

Industry Nine has some custom configuration options for the SOLix at the point of purchase, most notably the hubs being offered in 12 different anodised colours with matching nipples for an additional $150 / €150. The hubs cover all freehub standards (HG11, XD-R, Campy N3W and MS-R) and use a Centerlock disc fitment. The wheels can be specced with either 12mm thru axle or a quick release setup, and if you have some cash burning a hole in your pocket, the bearings can be upgraded to Ceramic for $580 / €525 extra.

Whether you upgrade to ceramic bearings or stick with standard bearings, the SOLix hubs use the same-size bearings on the drive and non-drive sides, evenly distributing loads across both sides. The bearings are protected from the elements by replaceable full-contact radial lip seals.

The 35mm profile I have on test is the shallowest depth in Industry Nine’s SOLiX SL aero range alongside 45mm and 65mm deep wheelsets, and there is also the option to mix and match with 35/45 and 45/65 combinations. Industry Nine says the 35mm rim shape was designed based on Computational Fluid Dynamics (CFD) and wind tunnel testing, although riders who are concerned with aerodynamic performance and want the fastest aero road wheels will gravitate towards deeper profiles. 

The inner rim diameter is verging on narrow by modern standards, measuring 21mm, and Industry Nine recommends tyres between 23-35mm. Although the inner rim is a touch smaller than other alternatives, the wide 29mm outer diameter helps give a smooth transition between the tyre and the rim and the thicker bead walls will help reduce pinch punctures. 

I initially fitted 30mm tyres which measured up a touch smaller, when I switched to a 28mm tyre it came up larger than their stated width. I fitted the same tyres to a set of Zipp 303 Firecrests which added volume to both tyres. We are only talking about a few millimetres either way here but it suggests to me the SOLix SL 35c rim is best suited to a 28mm tyre. 

Unsurprising as this is the tyre width Industry Nine optimised the rim for and it’s probably the tyre size most riders who are interested in the SOLiX SL 35c wheelset will run anyway. Our lab test proved that wider tyres are faster, so if you want to follow the science you will be better served by the SOLIX SL AR40c, which has a 25mm inner rim diameter and should happily accommodate the latest crop of 35-40mm road tyres. 

The rim is finished in a rather attractive gloss UD carbon finish with subtle black stickers, which can be jazzed up to match your bike's colour scheme by the aforementioned hub and nipple colour options. It's a great-looking wheelset and, although I’m not usually one for bright colours, I really like the extra pop from the Lime hubs on my test wheels.

The wheels are laced to the hubs with 24 straight-pull Sapim CX-Ray bladed spokes and the wheels are ready to go out the box with rim tape neatly installed and valves fitted. The rims have a hooked shape, so there should be no tyre compatibility concerns either. I fitted the wheels with a 30mm tyre, it only took a single blast of air to slip the tyre onto the bead in a very undramatic fashion, with no loud pops or sticky sections that refused to seat. I later switched to a 28mm Schwalbe Pro One and yet again, the tyre popped into place easily.

With my scales measuring a front wheel weight of 622g and the rear weighing in at 750g, the overall 1372g wheelset weight is competitive and undercuts the likes of Zipp’s 303 Firecrest which I would consider to be a benchmark in road performance wheels, although the Zipp offering has a wider and deeper rim profile which will account for the additional weight.

Performance

Out on the road, the SOLix hubs are truly instantaneous, immediately delivering any rider input to the rear wheel. Start pedalling and there is no delay or clang as the freehub pawls or ratchet gain momentum and slam into their interlocutors. Instead, the SOLix feels beautifully refined. 

I did a fair share of sprint intervals on these wheels and, under my max wattage, there was no indication of softness or flex from the pawls. Slam the pedals and the bike instantly surges forward. The millisecond gains in reaction time are probably not going to be the defining factor that wins you the town sign sprint or opens up a meaningful gap exiting a corner, but the direct and snappy reaction delivers a more energetic feel from the wheels that encourages a little more effort form the legs.

Freehub sound is a contentious subject with some riders preferring to make their presence known with a very audible rasp, while others prefer to roll silently past their surroundings. The SOLix delivers a wonderful buzz that climbs in pitch the faster you go. While it's clearly audible as you ride, it's not deafening or obnoxious and you can still hear what's going on around you. In fact, I am yet to find someone who dislikes the SOLix’s freewheeling song.

I find 35mm rim depth can be a bit of an awkward depth for road wheels and the SOLiX SL 35c wheelset is no different. There too heavy to fit in with the best lightweight wheels yet don’t offer sufficient weight savings over many 40mm rims, and deeper, options which can make up for the added weight by cutting through the air more efficiently. We haven’t subjected these wheels to our own lab-controlled wind tunnel wheel aerodynamic testing, so I can’t definitively comment on their aero performance. 

With that said, out on the road, they hold cruising speed well, although I did find I would have to work a little harder to maintain velocity on higher-paced rides, where deeper profiles can start showing their worth. For those that aren’t chasing every last watt at max velocity, there probably isn't all that much difference in the grand scheme of things as our lab testing only suggests narrow performance margins between the wheel depths. 

While the rims might not slice through the air as well as a more race-oriented wheelset, the bearings in the Solix hubs feel silky smooth thanks to the reduced pawl rotation and decreased pawl spring pressure. It's a sensation that's hard to quantify, but when you ease up on the pedals, the wheels continue to gently waft along the road with ease. The feeling is similar to Campagnolo’s wheels, which to me have always stood out as being noticeably smoother than other wheelsets.

Considering chains are rarely given a chance to become slack mid-climb, the SOLix’s engagement superpower isn’t a factor so there is little to separate these from other similarly specced wheels on the ascents. The smooth bearings, decent weight, and taught build make them a competent climber though, comfortably pacing up inclines and muscling up steep sections. 

It’s on the descents though that the SOLiX SL 35c wheelset’s strengths all come together and the wheelset comes alive. The agility offered by the 35mm profile gives control of line choice for perfect corner entry and when dipped towards the apex of a corner the lateral stiffness meant I could carve a precise curve through bends. Snap out the corner and the engagement immediately kicks in to sling-shot you towards the next bend. The descents are backed by a wonderful buzz from the freehub which further enhances the feeling of speed. 

After almost 900km of rough Scottish road rides the wheels are still straight and true with no need for additional attention. The bearings are also still spinning smoothly despite a healthy dose of wet weather riding.

Value

Arguing the value of a wheelset that costs the same as some of the best budget road bikes is going to be a hard sell when, on paper, they don’t provide any definitive performance upgrades. The SOLix SL 35c isn’t going to be as aero as deeper options and while the weight is competitive they don’t separate themselves from the competition in that area either. If you're solely on the hunt for performance it's hard to look past the likes of Scribe's Core SL 60, which scored extremely well in our lab test and weighs around the same as the SOLix SL 35c.

What makes the wheels stand out are the refinement of the SOLix hubs, the smoothness of the bearings, and the instant engagement combined with the overall handling qualities are impressive so if you’re looking for a road wheelset for general good vibes riding then they won’t be disappointed. It’s worth noting other brands are offering their own wheelsets built around the SOLix hubs for less outlay though.

Verdict

I have really enjoyed my time on the SOLiX SL 35c wheelset, they are lively, precise and buttery smooth. The rapid engagement feels incredible although admittedly offers less of an advantage on tarmac than they would in off-road applications. While the engagement is the headline spec, the auditory experience is wonderful and enhances the riding experience.  

With many other brands going to wider inner rim diameters to support ever larger tyre sizes, the 21mm internal rim diameter feels a touch narrow by modern standards.  The wheelset demands a premium too which puts them in line with many modern deep-section wheelsets which offer an aerodynamic advantage without being a drag up steep inclines. It's easy to get caught up in the numbers though and while competitor wheels may offer marginal gains, it doesn’t change the fact that the SOLiX SL 35c wheelset is a delight to ride.

While I was impressed with how the 35c wheelset performed on smooth tarmac these aren't the wheels I would spend my own money on. The poor conditions of my local lanes and ‘a little gravel never hurt anyone’ approach to route planning means calls for a wider tyre, so I would be investing in Industry Nine’s wider and deeper SOLix SL AR40c wheels for wider tyre compatibility at a penalty of just 50g.