Back in 2017 I was roaming the halls of Eurobike (the world’s biggest bicycle trade show) and something caught my eye on Scott’s stand. The Swiss bike maker always goes big at Eurobike: the brand’s stand itself is huge, generally occupying at least eight regular pitches, and more often than not, you can spot a sponsored pro or two loitering about under the spotlights, doing their best to look like they’d not rather be riding. There’s energetic background music, big TVs showing cool cyclists doing cool cycling things, and sometimes free coffee too.
All Scott’s latest and greatest bikes, kit and components are on display. What grabbed my attention that year wasn’t the jewel in the Scott stand’s crown though, the brand’s then recently renovated Foil aero bike (it promised aerodynamic efficiency without the ride quality of a jackhammer, which was a new concept at the time, and even had disc brakes!), but a new mountain bike wheelset from Scott’s components brand Syncros, tucked away, low-key, in a corner.
The Syncros Silverton SLs were a marvel. DT Swiss supplied the hub internals and custom-made shells, but otherwise the spokes and rims were effectively one-piece carbon composite, making a weight of just 1,250g possible. They were Lightweight-esque, but modern in spec – hookless rims, 26mm internal width, tubeless-ready and sturdy enough to stand up to cross-country mountain biking.
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Had the hubs not used Boost spacing (a mountain bike standard that is wider than road), I’d have repurposed the Silverton SLs to use on a road bike and there’d have been a review in years ago. I asked Scott at the time when a road-going equivalent would be available. ‘They’re in the works.’ Those works took five years to complete, but in 2023 the Capital SL arrived, and having finally got the chance to get some kilometres in on the design, I can say that even though it has been a long one, the wait has been worth it.
Some for the road
Compared against their Silverton forebears, the Capital SL wheels focus more on aerodynamics. They are offered in two depths – 60mm and 40mm – with the latter weighing an unbelievable 1,170g. As road wheels don’t have to be as burly or wide as MTB equivalents, Syncros could pare back the Capital SL’s design by reducing aspects like spoke count. This allowed it the opportunity to deepen the rim and consequently marry light weight and aerodynamics in a way almost no other wheelset on the market does.
While the Capital SLs aren’t MTB-level tough, Syncros still rates them up to a 120kg bike+rider system weight, and the wheels’ internal rim width is equally real world-friendly, being 25mm and geared around wider tyres. The rims are hookless, which would ordinarily limit tyre choice, but Syncros has, in a way, mitigated that to an extent in this instance by working with Schwalbe on Capital SL-specific version of the Pro One tyre. The Pro One Aero variant is different front and rear, with the front having a thinner, more pointed tread cap for aerodynamics, and the rear having a thicker tread for better grip and puncture protection. The tyres are 28mm wide, but despite the latest ETRTO guidelines stating that 25mm internal width rims should be used with tyres no narrower than 29mm, Syncros insists it is entirely safe. Crucially, this is a recommendation and not a rule.
‘We have co-developed a matching aero rim/tyre pairing with Schwalbe which has been thoroughly tested in the wind-tunnel for aero performance but also in the lab for safety. The combination passed all Schwalbe’s internal test standards, which are the same for hooked rims,’ says Christoph Dadaschi, Syncros’ product manager.
Labour of love
The Capital SL 40s price is undoubtedly exorbitant, but the level of complexity involved in their fabrication goes some way to explaining their cost. Each side of the hub flange subassembly (which is an intricate little thing in itself) gets four ribbons of carbon looped around it. They both originate and insert on the rim, creating eight spokes for each side of the wheel. Where the spoke ribbons cross, they are interwoven, so become structurally cohesive, then the rest of the rim is laid up to intermingle with each spoke attachment point. The entire wheel is done at once, in one jig, by hand.
Once cured, the proprietary aluminium hubshell is bonded in to space the hub flanges and tension the spokes. There’s no option to adjust them if they aren’t true or round, it’s a case of scrapping the product and starting again. From the user’s perspective, this means that by definition the wheel will be right from the start will stay right without any attention required, though the wheels cannot be repaired if damaged.
Syncros says the spokes are 33% stronger than steel equivalents, and offers a two-year warranty and discounted crash replacement policy in an attempt to offset this, but I do think the cover could be more comprehensive to assuage the fears of those who are investing so much.
‘We are trying to make the whole manufacturing process as efficient as we can but fabricating, and specifically the preforming, each wheel requires a lot of manual labour which is the biggest cost driving factor,’ says Dadaschi. ‘We feel that there are still consumers willing to pay such price for given performance benefits, plus if we compare the high retail price of our wheels to others in the category though, relatively we are competitive.'
I can’t really argue with Dadaschi here, for in this rarefied stratum of the market the Capital SLs do seem offer good ‘value’ based on some key objective metrics.
Partington’s R-Series MKII R39/44 are around same weight at a claimed 1,160g, but considerably narrower internally at 21mm and £1,500 more expensive. Likewise, Lightweight’s Obermayer Evo wheels are a touch heavier, archaically narrow at 18.2mm and cost a whopping £7,060.
Cadex’s brand new Max 40 Disc Tubeless are the Capital SL’s closest competitor now, beating Syncros’ wheels on price by £500 or so and coming with 70g of their weight. Cadex claims its Max 40s are stiffer, but they aren’t as wide tyre-friendly as the Capital SLs, having a 22.4mm internal width.
As for more mainstream options, Enve’s 3.4 and Zipp’s 353 NSW models do get close, offering the same 25mm internal width as the Capital SLs at a lower cost, but neither can really compete on weight.
Putting the theory into practice
The futuristic design of the Capital SLs lends an aggressive look to any bike, and Syncros says it has the data to show the wheels’ advantages extend beyond the superficial. The wheels test faster than established competitors at a similar depth, with the Capital SL’s advantage growing at wider wind angles. Switching between the Capital SLs and more conventional wheels of a similar depth was indeed night and day different in terms of the feeling of speed. However, because in general, aerodynamic properties are nuanced at best and hard to define, I don’t believe it’s in drag reduction that the Capital SLs stand out.
It’s the combination of stiffness and low weight of these wheels that make the difference. The 300g or so these wheels shed over more regular wheels of this depth isn’t all that much in the wider context of the whole system, but the drop in weight combined with the rigidity of the all-carbon construction meant the bike I was using them in felt shockingly quick to accelerate. The wheels gave the impression of tuning the bike up: even the handling got sharper.
Largely thanks to the wide rims nicely supporting those big and supple Schwalbe tyres though, this cutting edge didn’t tip over into harshness either. The rim and tyre pairing can reconcile immediate responsiveness under acceleration with relative comfort and control over more broken tarmac.
Largely, this’ll be because Schwalbe’s Pro One tyres are superb even in their normal guise, but it seems feasible that the front/rear-specific Aero derivation certainly didn’t hurt performance out on the road – just like wheels, tyres are subject to different conditions front and back, so why should their designs be interchangeable? It is great to see Syncros/Schwalbe account for this and something I think we’ll see more of in the future.
The Capital SL 40d weren’t all fun and games however. Despite the rims’ fairly blunt profile that Syncros credits with providing drag superiority over competitor designs at wide yaw angles, I’d say the front wheel did feel a little snappier than I’d expect for its depth in a crosswind. Gate gaps in hedgerows prompted a little more feedback through the front end than I’d ideally have liked – a quality that could be down to the sheer lack of inertia plus the increased lateral surface area of those bladed spokes.
I also think Syncros missed a trick not including hybrid ceramic bearings as standard on such an expensive wheelset. Their benefits might not be clear cut, but I think it’s reasonable to expect this type of products to come with all the bells and whistles as standard.
Minor gripes aside though, the brand has achieved something special with the Capital SLs. Their cost is exclusive, but then again, the price of genuine progress has always been high.
