Soul S4.0 wheelset review
Based in Singapore, Soul is a rider-owned company that concentrates on affordable race-worthy frames and wheelsets. The company offers both alloy and carbon wheelsets with rim profiles ranging 22-62mm. In this review, CTech editor Matt Wikstrom takes a look at Soul’s S4.0 wheelset that is built with 40mm alloys rims.
Sean Wei is responsible for Soul. Trained as an architect, he has a discerning eye but it was his passion for racing that inspired Soul’s inception. His ambition for the company is simple enough, to create reliable products that are light and race-worthy with a reasonable price.
Based in Singapore, Soul’s first product was a titanium frame. The company now offers three frames along with a wide range of wheelsets. Indeed, there are four alloy wheelsets, two carbon clinchers, and two carbon tubular wheelsets while disk versions and carbon/alloy hybrid rims are in the works.
Soul has a very active role in the design of the rims and hubs. The company invested in its own moulds for its carbon rims and then went about gaining UCI approval for them. At the same time, Soul designed and then refined its Prodigy hubs to be both light and robust.
For this review, Soul provided its revised S4.0 wheelset that was unveiled at the Taipei Bike Show earlier this year.
Before the Ride
The S4.0 wheelset is built with 40mm rims that are 23mm wide with a ~19mm bed. The rounded rim profile is derived from Soul’s FOILX design developed for its C5.0 and C6.0 carbon rims. As such, the rim bulges near the brake track to improve laminar flow while the wide rim improves airflow at the junction with the tyre.
Soul designed the Prodigy hubs that serve all of their wheelsets. Now in its fourth iteration, the hubset was designed to be robust with a low overall weight. At the same time, the dimensions of the hubs allow for a single length spoke to be used for the entire wheelset.
The hubs have alloy axles that revolve on cartridge bearings (two for the front, four for the rear). End caps thread directly into the axles, however there is no adjustment for bearing preload. Buyers have a choice of Shimano/SRAM- or Campagnolo-compatible freehub bodies.
The 18-hole front hub has very wide flanges to improve the stiffness of the wheel. The rear hub has 24 holes. Radial lacing is used for the front wheel and non-drive side of the rear wheel, while two-cross lacing is used for the drive side. Pillar supplies the bladed spokes. Total weight for the wheelset is 1,671g sans rim tape and skewers.
The hubs are very easy to break down for care and servicing. A pair of 5mm Allen keys are needed to remove the end caps. Soul recommends thick oil for the pawls of the freehub and some grease to improve the water resistance of the bearing seals.
The S4.0 rims are gloss black with a machined brake track. Bold white logos are added to complete the finish, however buyers can elect to buy a set of grey logos to tone down the presentation. The gloss finish recalls an earlier era but distinguishes Soul’s wheels from its matte black competition.
The Soul S4.0 retails for USD$560 (AU$649) while delivery will add another US$60-80 (AU$64-86), depending on location. The wheelset is supplied with hollow steel skewers. The wheels can be customised with options for coloured end caps (red, blue, silver), nipples (red, blue, silver, gold, pink), and hubs (red, blue silver, white). For more information, visit the Soul website.
After the Ride
A few years have passed since HED introduced wider rims for road wheels and the benefits continue to impress me. More comfort, greater grip, and lower rolling resistance were all evident in Soul’s S4.0 wheelset thanks to the wide rim bed. In short, it’s an easy wheelset to like: smooth, fast, comfortable, and sure-footed.
The 40mm tall alloy rims have their pros and cons. The deep profile makes for stiff rims that inspired my confidence when I was attacking or sprinting out of the saddle. Big, powerful riders will appreciate how sturdy the S4.0 wheelset is under load but there is a minor weight penalty.
Soul has done a great job in keeping the total weight of the wheelset below 1,700g, however the rims suffer from a measure of inertia on any slope. There’s nothing surprising in that, and riders looking for more performance on the slopes will find more appeal in the S2.0 wheelset that weighs just over 1,300g.
The S4.0 wheelset was well behaved in crosswinds. I suspect the extra weight of the alloy rim added to the stability of the front wheel, allowing me to concentrate on my effort rather than getting distracted by unpredictable handling.
Soul offers no data on the aerodynamics of its FOILX shape. Out on the road, such benefits are too difficult to discern, more so when the flywheel effect of the rim can add to the speed of the wheel. Regardless, I never struggled to get the S4.0s rolling, and I never felt like I was wasting my energy.
The machined braking track was smooth and effective, as can be expected for alloy rims. There was some minor pulsing during braking, suggesting the braking tracks were not quite uniform, the only imperfection in an otherwise impressive wheelset.
Final Thoughts and Summary
The S4.0 will suit those riders with plenty of power that thrive in undulating terrain. It is a sturdy wheelset that offers plenty of sure-footed comfort thanks to its wide rim bed. And when compared to similar wheels from Shimano, Mavic or Fulcrum, Soul’s S4.0 trumps each on the basis of price or weight, and in some instances, both.
There are two other models in Soul’s alloy road wheelset range that differ only in the height of the rim. The S2.0 has a 22mm rim while the S3.0 has a 32mm rim. I’d expect both to offer the same comfortable and sure-footed ride as the S4.0 with less inertia and stiffness. Thus, buyers need only to decide which profile suits their needs to enjoy a fine and well-priced alloy wheelset.