Swiss Side Hadron2 Ultimate 625 Disc wheelset

When we say wheels are the best bang-for-buck upgrade you can get, it's because of the performance gains delivered by hoops such as this, the Swiss Side Hadron2 Ultimate 625 Disc Brake wheelset. These wheels are exceptionally fast, stiff and virtually unaffected by crosswinds.

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Jez has tested a few sets of Swiss Side's Hadron wheels in the past, including the rim-braked Hadron Ultimate 625 back in 2017, and was generally very impressed. For 2020, though, they have had some upgrades.

Their new 62.5mm-deep rim is said to reduce aero drag by between 10% and 20% across the range (50mm and 80mm depths are also available), and steering moment is reduced by 26% to increase stability in varying wind angles.

Stability

Apart from the speed, that stability is the stand-out bonus of these wheels compared to many others. I spent years time-trialling on some very fast courses around southern England and in Wales on a range of deep-section wheelsets, and I've never known one as competent at dealing with crosswinds as this.

I only felt a nudge once through the handlebar when passing a gateway with a full-on sidewind, and I'd been so immune until then it was a proper 'what the hell was that?' moment.

At the widest point the 625's rim is 30mm (20mm internal), which Swiss Side says is best mated to a 25mm tyre for ultimate aerodynamic efficiency (although you can get away with a 28mm on the rear if you want a bit of comfort as well as speed).

Maximum tyre width is 64mm.

Tubeless setup

The majority of testing took place using Pirelli's P Zero Race TLR tyre in a 25mm width, and as you can see from the photos on that review, the transition from tyre to wheel is pretty seamless. I found tyres easy to fit, too. Snug enough for a really good seal, but you'll be able to take them off at the side of the road should the need arise.

Adding the tubeless sealant (these wheels come ready-taped and with valves) saw a bit of seepage between tyre and rim, but this was soon dealt with and the tyres kept good pressure.

The Hadron2s spent a lot of time on the Ribble Endurance AL, a bike I like a lot but one that's not necessarily aero or lightweight.

Swapping the Ribble's Mavic Aksiums for the Hadron2s knocked off about 400-500g, but the difference in performance was absolutely huge! I'm not saying many people are going to purchase a near two grand set of wheels for their £999 bike, but it does highlight the efficiency you gain focusing on aerodynamics over solely weight if you ride a mixture of terrains.

My old commute was 34 miles there and back, and I still ride it now for testing, but all in one go. Having ridden it pretty much five days a week for seven years, I've covered every mile in every weather, and on a multitude of bikes. I know what speed I should be achieving on every section for the conditions.

On flat sections and descents the Hadron2's gains were big, an extra 3-4mph over the Ribble's standard build. Taking the climbs into account, the whole ride was normally done at 1.5-2mph faster.

Swiss Side hasn't been shy with its data, and you can find all the testing results on its website.

Even with the Swiss Sides fitted the Ribble was still around 9.5kg, so I certainly wasn't dancing up the hills. I hit the bottom of them faster though due to the speed I was carrying on the flat, and when I had to get out of the saddle and sprint for the top the Hadron2s showcased their impressive lateral stiffness.

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I ride with my tyre pressures high – it's the way I like it – and with 100psi in the 25mm Pirellis, the overall ride feel was absolutely fine. Firm, but not harsh like some deep section carbon rims can be.

As for the build, Swiss Side hasn't scrimped on components, with a mixture of DT Swiss Aerolite II and Aero Comp II spokes in a 2-cross pattern You get 24 both front and rear.

The DT Swiss aluminium nipples are hidden which gives a smooth clean look. The only downside is that if you whack a pothole and they go out of true, you aren't going to be fettling them at the side of the road with a standard key. Still, you can get away with a bit of side to side movement on a disc wheel, whereas you can't on a rim brake option.

DT Swiss also provides the hubs with their 180 DICUT fitted with Sinc Ceramic bearings, which are as smooth as smooth. If you like a bit of freehub noise you'll be a happy bunny, as the 180s have a reassuring click. It's not so fast it becomes irritating, though.

The freehubs

As standard these wheels come with a Shimano/SRAM compatible splined freehub body, although you can get kits for Campagnolo or SRAM XDR. They cost €57 extra, though (around £51) which on a wheelset of this price is disappointing – should surely these should come as a standard option.

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Out of the box they're set up for 12mm thru-axles, but are supplied with interchangeable end caps to work with quick releases. The brake rotor mounts are Shimano's Centre Lock standard.

Value

Priced at €2,142.58 (roughly £1,920 at the time of writing), this is up there with a lot of other top-end manufacturers, but I'd say you're getting a lot here for your money.

Campagnolo's Bora WTO 60 Disc wheelset drops about 100g and costs under a tenner more at £1,928.99. Liam couldn't really fault them at all, whether on the flat or in the hills, though the rims are a bit narrower both internally and externally and Campag don't supply any specific aero data.

If you aren't bothered about ceramic bearings, you can get the disc version of Edco's SIX-4, a wheelset I really liked. They have a claimed weight similar to the Swiss Side's measured weight, and cost just £989. They aren't quite as fast, but they are certainly a good price.

If you want a wind-cheating set of wheels and your budget stretches to two grand, Swiss Side's Hadron2 Ultimate 625s should definitely be on your short list. They're fast without being affected by crosswinds, offer great levels of stiffness, and the build quality is top drawer. It's just a shame that Campag or XDR users have to pay more.

Verdict

Seriously impressive aerodynamic wheelset that delivers real-world speed and stiffness