Vitus Substance CRS-2 eTap AXS Rival gravel bike review

The Substance denotes Vitus’ range of gravel bikes, designed to be capable off-road and comfortable over long distances. The wide range of mounting options for bags and accessories make them well suited to multiday trips, should that be something you’re considering. This CRS-2 eTap AXS model is Vitus’ top spec build, coming with SRAM’s 2x12 Rival AXS groupset which features electronic shifting and hydraulic braking.

Frame

Starting with the heart of the bike, the Substance CRS-2 Rival AXS is equipped with a carbon frame and fork with specced tyre clearances of 650b x 47mm or 700c x 42mm. This is a little on the narrow end for a gravel bike, typically you’d expect a frame to be rated for 650b x 53mm (2.1 inches) or 700c x 45mm. There is, however, masses of clearance around the stock 650b x 47mm WTB Venture TCS Road Plus tyres, so there is scope for squeezing in something a little larger.

There are additional bottle bosses on the under side of the downtube and on each of the fork legs, providing an easy avenue for a bit of extra carrying capacity. In addition to this, there are also the more traditional mounts for a full set of mudguards and a rear rack. Some brands are moving away from including these on their gravel bikes, trying to create a clearer delineation between gravel and touring/commuter bikes – but extra versatility is rarely a bad thing.

The geometry of the frame has been chosen to favour stability. The head angle is on the slacker side at 71.5 degrees in a size medium, which generally has the effect of making the steering a little less twitchy. For context, gravel bikes have generally have head angles of a bit over 72 degrees, while the slackest tend to be at around 70 degrees. 

The bottom bracket drop is 68mm, which is reasonably low – although again not boundary pushing – and has the effect of lowering your centre of gravity, making you feel as if you’re ‘in’ the bike, rather than perched on top of it.

Although the Substance CRS-2 Rival AXS is in line with the majority of gravel bikes with its 435mm chainstays, this is still fairly long. The effect of this is to again make the bike feel more planted and stable, but the flip-side of this is generally a bit of a less responsive in sharp corners.

While some brands are heading further down the path of proprietary parts and unusual standards, the CRS-2 Rival AXS has a few elements which should make it easier to live with. For starters, the bottom bracket is threaded, rather than a press fit, which makes it easily replaceable by a home mechanic. The seatpost is has a common 27.2mm diameter and the axle spacing is a standard 12x142mm on the rear and 12x100mm on the front – no surprise switch to 15x110mm here.

Groupset

SRAM Rival eTap AXS really is excellent and provides a genuinely compelling case for keeping the front derailleur – whereas the limitation of some other 2x setups make them a little harder to justify. Rival AXS is a groupset rarely seen at this price point, so its presence is a big perk for the CRS-2.

Part of what makes 2x12 Rival AXS so good is the range of the gears. The bottom gear is lower than you can get from Shimano’s 2x11 GRX gravel groupsets, which makes steep climbs when heavily laden easier to manage. 

At the other end, the Rival AXS’s largest gear combination of 43x10 is bigger than Shimano GRX’s 46x11, although it is a little smaller than the largest GRX combination Shimano has on offer, 48x11. This means that there’s plenty to push against when cruising down descents – that is, until you get to about 60kph, but by then you’re generally better off tucking up than continuing to pedal.

Although the gearing range is wide, 2x12 Rival AXS also manages to keep the jumps between the gears quite small. This has the result that you don’t find yourself stuck between two gears – one too hard and the other too easy – quite as often.

With SRAM’s 10–36t cassette, there’s a total of three single tooth jumps, going: 10-11-12-13-. On Shimano’s 11-speed GRX cassette, which spans 11–34t, there aren’t any single tooth jumps at all, going straight from the 11t smallest sprocket to a 13t sprocket.

Then there’s the chainrings. A ‘traditional’ sub-compact crankset of 46/30t preserves the 16t jump that’s been around on road cranksets for a while – but because the chainrings are smaller, that jump is proportionally larger. On a 52/36t semi-compact road crankset, the difference between the gears is about 44 per cent. Whereas, on a sub-compact, this jumps up to a whopping 53 per cent and can feel quite jarring and needs a lot of compensation shifts at the cassette. 

The SRAM Rival chainrings on the other hand, at 43/30t, bring the difference between the gears back down to around 43 per cent, which is much more manageable. The smaller sized big ring also means you can stay in it for longer, treating it almost like a 1x setup, but with a bailout option for when it gets properly steep. 

The rotors are 160mm both front and rear, which is quite standard for a gravel bike. Some brands are starting to upsize the front to 180mm, which could be beneficial for heavier riders on long descents with a fully laden bike. But at 68-ish kg, even with a full complement of bike packing bags, I’ve never required anything larger than 160mm.

Wheels

These are the Prime Kanza 650b Aluminium, which look to have been renamed as “Orra”. They have an internal rim width of 21mm, which is a bit on the narrow side by today’s standards. With the relatively wide 47mm WTB Venture TCS Road Plus tyres, a wheel with an internal width of about 24mm would offer a bit more support for when running the tyres are low pressures (for me, around 22 psi on the front and 24 psi at the rear). 

But for the amount it would cost, it wouldn’t be worth upgrade the wheelset just for a wider internal width – you’d be better off saving up a bit more for something a little higher end in all respects.

The WTB Venture TCS tyres have quite a fine file tread, making them better suited to hard and dry conditions. As stock tyres go, they aren’t at all bad, but if you’re expecting to ride in loose and muddy conditions, expect to upgrade these tyres to something with a bit more bite fairly quickly.

The ride

Vitus has got the build of the Substance CRS-2 pretty spot-on for long-distance riding on gravel tracks. Taking it along the ridgeline of the South Downs Way, the feeling of planted stability gave bags of confidence for just letting go and plummeting down the wide, open descents.

With the Downs being quite so rough, I would want to swap out the tyres for something a little wider – although the specified maximum clearance is 47mm, there’s enough room for me to be comfortable with at least a 50mm. I’d also want a tread pattern with a bit more space between the knobs for some added grip on fine, shingle-y gravel.

But with tyre choice being so terrain dependent, you’ll rarely come across a bike with the exact right rubber for you – and if you do, that just means they’ll be totally inappropriate for someone else’s situation. But with that said, the levels of comfort and grip offered by the WTB Venture TCS Road Plus tyres does still make them a pretty good option for quite a wide range of use cases.

Although – or rather, because – the handling and rider position are so set for stability and long-distance comfort, the handling on tight and twisty trails is compromised a little. That long wheelbase meant the CRS-2 felt a little cumbersome when trying to thread it through the trees on wooded singletrack trails.

That sort of riding is still perfectly possible on the Substance, it’s not as though that door is being completely shut on you as it would be if you were on a touring bike, for instance. But with that said, if you are planning on riding in the woods more so than on wide, open tracks, you'd be better off opting for a bike with chainstays a little shorter, at around 425mm. 

Loading the bike up into the corners, the tyres did feel a little squirmy on those 21mm internal width Kanzo rims. A switch to wider rims, around 24mm internally, would help to provide a bit more support for the tyres. But the wheels themselves actually felt surprisingly zippy and quick to accelerate.

I didn’t go on any multiday trips on the Substance CRS-2 Rival AXS, but with those fork bosses in addition to the underside of the down tube ones, loading up would have been quite easy to do. The rack and mudguard mounts are also good inclusions for a bit of extra carrying capacity and giving the option to set the bike up for road miles in the winter, when the trails aren’t so fun.

I really appreciated the Rival groupset, with the large paddles on each side, shifting is super straightforward and it’s very difficult to accidently miss-shift. The 43t big ring was an excellent balance, providing gears as large as I needed, while also being small enough that I didn’t have to shift rings often at all. But when I did, the drop down to the 30t inner ring was a lot less jarring than with other gravel groupsets.

Value

The Vitus Substance CRS-2 Rival AXS is really pretty excellent value. For a carbon frame and electronic gears, you’re typically looking at over £3,500, whereas the Vitus Substance comes in at £2,499.

There are some exceptions, such as Boardman’s ADV 9.4 gravel bike which comes with SRAM’s new XPLR 1x12 drivetrain and costs £2,500. But even UK-based direct sales brand Ribble starts at £3,199 for its Gravel SL gravel bike with electronic shifting.

In our recent £3K gravel bike grouptest, none of the bikes had electronic shifting – one of them was even running Shimano GRX 2x10, which is a pretty stark contrast.

The only area where the Vitus Substance can really be criticised is internal rim width of the wheels, which at 21mm is a little bit on the narrow side – particularly for 47mm wide tyres. But these aren’t exactly super narrow and aren’t something you’d be rushing to upgrade.

Verdict

The Vitus Substance is an incredible value gravel bike. The ride is great for long distance riding, where stability is the priority. There’s an excellent range of mounting points, with extra downtube and fork mounts you’d want for bikepacking – but also mounts for a rear pannier and mudguards too, boosting its versatility.

The build, together with the carbon frame, comes to a respectably light weight, while the 2x12 SRAM Rival groupset provides an excellent gearing range – at both the high and low end – while retaining small jumps between the gears. Aside from the electronic actuation, the spread of gears just themselves are super compelling.

The only real criticism of the bike itself is the relatively narrow internal rim width of the wheels, which at 21mm, don’t provide such a good match for the tyres.

One other thing to note, though, is that the stability which makes it great for long distance riding on non-technical terrain does hobble the bike a little for tight and twisty singletrack riding. If you’re planning on riding mainly on trails generally ridden by mountain bikes, you’d be better off on a frame with geometry that’s a little more nimble.

Specs

• Frame: Substance Carbon
• Fork: Substance Carbon
• Shifters: SRAM Rival eTap AXS 2x12  
• Crankset: SRAM Rival D1 DUB Wide, 43/30t  
• Derailleur: SRAM RIVAL eTap AXS 12 Speed, 36T Max
• Cassette: SRAM XG 1250 D1 10–36T
• Brakeset: SRAM Rival eTap AXS D1 Disc
• Wheels: Prime Kanza 650b Aluminium Disc wheelset
• Tyres and clearance: WTB Venture TCS Road Plus 650b x 47 tyres (Max: 650b x 47mm or 700x42c)  
• Head angle: 71.5 degrees
• Chainstay length: 435mm 
• BB drop: 68mm 
• BB: SRAM DUB 386
• Weight: 9.6kg (size medium, measured)