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Swiss Side Hadron Ultimate 625 wheelset



Fast and stable, a great perfomer once braking issues were sorted, but is it worth the extra over the standard Hadron?

At every product is thoroughly tested for as long as it takes to get a proper insight into how well it works. Our reviewers are experienced cyclists that we trust to be objective. While we strive to ensure that opinions expressed are backed up by facts, reviews are by their nature an informed opinion, not a definitive verdict. We don't intentionally try to break anything (except locks) but we do try to look for weak points in any design. The overall score is not just an average of the other scores: it reflects both a product's function and value – with value determined by how a product compares with items of similar spec, quality, and price.

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The Hadron Ultimate range from deep-section upstart Swiss Side takes a lot that we loved from the Hadron wheels (we've previously tested the 485 and the 625) and pimps it up with full-carbon rim construction and spanky ceramic bearings, as well as adding disc brake versions to the range. They remain a superb-handling deep-section wheel, now with a lower weight and a higher price. The move away from an aluminium braking surface has some of the downsides you might expect, though.

As with the previous Hadron range, the new Ultimate wheels are available in a choice of depths. These 625 wheels at 62.5mm rim depth are in the middle of the range, with the 485 below and the 800+ above (which has 80mm front and 85mm rear). All depths are now also available with disc-compatible hubs, which is good news. The rim is the same whether supplied for rim brake or disc brake.

> Buy these online here

Where the original Hadron range had an aluminium structure and a thin carbon fairing, here the whole rim is built from carbon, but still in a similar fashion. The fairing appears similar or identical to that used before, with the spokes still passing through the inner edge to hidden nipples on the outer structural part of the rim.

Swissside Hadron Ultimate 625 wheel set - rim bed.jpg

Another significant change is that the Hadron Ultimate range are tubeless-compatible, a first for Swiss Side. They are supplied taped, meaning that even if you're running them with inner tubes, truing is going to be a bit awkward. Happily our test wheels were true when unboxed and remained so throughout the testing. Swiss Side uses quality Sapim CX Ray spokes, with 16 laced radially at the front and 21 at the rear (7 radial spokes on the non-drive side and 14 in a 2-cross pattern on the drive side). Bonus point duly awarded for the use of brass nipples.

Swissside Hadron Ultimate 625 wheel set - detail.jpg

The hubs are the same as those used in the Hadron range but with an upgrade to Enduro ceramic hybrid bearings. Ceramic hybrid means that the races are conventional hardened steel while the balls themselves are made from ceramic silicon nitride. Check this link if you're wondering about whether ceramic bearings are worthwhile. We conducted a simple spin down test between the front wheel on test here and the Hadron 625 with its standard ball bearings. The Hadron Ultimate has a lower inertia thanks to the full-carbon rim but was still spinning after the Hadron had stopped (which – truth be told – took a really long time anyway), suggesting that there is indeed lower friction here.

Swissside Hadron Ultimate 625 wheel set - rear hub 2.jpg

The hubs are forged and machined to a good finish. My only criticism regards the freehub, which suffered badly from being bitten into by the cassette. It appears the same as the one used in the standard Hadron, but my first 500km on these wheels were spent in the Pyrenees after which it was quite tricky removing the cassette. A couple of steel 'anti-bite' strips would be a really worthwhile addition.

I've ridden these wheels for the thick end of three months, in the mountains and in the rolling terrain around Bath, and they compared largely as expected to their alu/carbon brethren, which is to say exceptionally well behaved in the wind and with (per Swiss Side's well documented testing) a significant aerodynamic benefit. Braking suffers – again, as might be expected – especially with the Equinox pads that are supplied as standard. 


Let's take the aerodynamic benefits first. Swiss Side claims that these are marginally more aerodynamic than the equivalent-depth Hadron, saving 10.5W at 45kph compared to a reference shallow-section rim (compared to 10.0W for the alu/carbon Hadron). Swiss Side reckons that over 40km this would give a saving of 97 seconds.

Swissside Hadron Ultimate 625 wheel set - rim decal.jpg

As far as I know, no wheel manufacturer has been as open about its test and development programme as Swiss Side, inviting journos (including us) to spend time with them in the wind tunnel and doing comparative tests with the Big Names in the wheel market, which it reckons show that the Hadrons display similar drag to some of the leading rivals (which cost quite a bit more) while also offering better crosswind stability than many of them.

We talked to Jean-Paul Ballard, the technical director and co-founder of Swiss Side, who explained that "aerodynamic stability is a big focus of ours at Swiss Side as we've identified that this is where big performance gains can be made by effectively reducing rider drag by keeping them in a lower, stable, confident position more of the time". In other words, if you're more confident in the wind, you'll stay in an aero position more of the time, which itself contributes more to your speed than any wheel will.

Indeed, just as we found with the previous Hadrons we've tested, the Ultimate 625 gives you a real sense of confidence on windy days. Even riding across the M48 bridge to Wales on a blowy day to see the Tour of Britain was a much less alarming experience than you might imagine. The wide, U-shaped rim profile is very similar to that used in the Hadron 625, and the key dimensions are identical (27mm max width, 23mm across brake surfaces). The slight improvement in aerodynamics is apparently due to a minor modification in the shape of the rim and the resulting change in how the reference tyre sits against the rim. Obviously it would depend on your choice of tyre anyway.


What of braking then, the habitual bugbear of a carbon rim? With the supplied pads, Equinox BR006, they do a respectable job of slowing you down, but at ambient temperatures any higher than mid-teens made an appalling noise while doing so. Setting them up toed-in didn't help, and the screeching was such that I found myself trying not to brake unless I really needed to, which wasn't ideal. On long Pyrenean descents there were times where the power seemed to drop off as the pads and rims heated up. Also not ideal.

Pad wear was a problem too – 500km in the mountains and they were toast. Chatting to Swiss Side about this, I was told that the choice of pad was imposed upon Swiss Side by its rim manufacturing partner, but said partner sent a set of SwissStop Black Prince pads over for comparison and they were a massive improvement (and are also approved for use with these wheels). Thankfully, the screeching noise vanished and the wear rates became rather more acceptable. It appears on its website that Swiss Side still supplies the Equinox pads as standard, so I would strongly recommend replacing them immediately if you buy these wheels.

Swissside Hadron Ultimate 625 wheel set - rim detail.jpg

Swiss Side made a video talking about the design of the wheels, in which it discusses the unusual approach of using two-part construction for a full carbon rim. This, it is claimed, allows it to "decouple the lateral stiffness from the vertical stiffness". In my experience, it's extremely hard to detect any noticeable variation in vertical stiffness from one wheel to another. There's an argument that deeper rims and shorter spokes makes for a harsher ride, but it's not one I'm really convinced by. Here, I would suggest that the relatively wide rim profile and consequent effect on the tyre shape and volume has a greater effect than the fact that the spokes pass through the fairing.

> How to get more aero without spending a fortune 

Lateral stiffness, on the other hand, is certainly an area where there is variation between wheels, and one where I was a bit disappointed with the Hadron Ultimates. At the rear, particularly, it wasn't overly difficult to provoke brake rub, and I had to set my brake pads wider than I would have liked to eliminate it. I hadn't noticed this being a problem with either of the alu/carbon Hadron wheelsets I'd tested previously. Curiously, Swiss Side told me that lab tests show the Hadron Ultimate to be laterally stiffer than the equivalent Hadron, leading me to wonder whether it was simply the fact that brake rub on carbon makes a more audible noise that made me more aware of it here.

The Hadron Ultimate wheelset is supplied with branded QR skewers and spare spokes. Wheelbags aren't included but are available for an extra cost. Maximum rider weight is 105kg and maximum tyre pressure is 120psi.


We scored both previous Hadron wheelsets highly on and I had big expectations for the Hadron Ultimate. In most respects it is a really impressive wheelset, giving the same blend of straight-line speed and superb stability as the Hadrons, and saving a useful chunk of weight too (nearly 200g lighter than the same depth Hadron wheelset). Braking with the supplied pads is very disappointing, though, and not for lack of outright stopping power – the noise that accompanies it and the pad wear are the worst I've experienced. Happily, that's a problem that is easy to fix by swapping pads – these should really be included.

> Read our buyer's guide to road bike wheels

Measuring these up against competitor wheels I would say they do pretty well – they are fast, a good weight for the depth and their stability makes them among the most reassuring of deep-section wheels on a gusty day. The price represents a chunk of cash, sure, but against wheelsets from the likes of Zipp and Enve it looks like good value.

For me, the bigger question – if it was my money – is: are they worth the extra money over the alu/carbon version? Right now you can get 10% off the Hadron Ultimates and 20% off the Hadrons, making the Ultimate 625s more than 60 per cent pricier than the Hadron 625 wheelset. The extra money gets you a lighter and decidedly better-looking wheelset, but if I'm honest I'd probably buy the standard Hadrons, which are currently something of a bargain.


Fast and stable, a great perfomer once braking issues were sorted, but is it worth the extra over the standard Hadron?

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Make and model: Swiss Side Hadron Ultimate 625 wheelset

Size tested: 62.5mm deep

Tell us what the wheel is for, and who it's aimed at. What do the manufacturers say about it? How does that compare to your own feelings about it?

Swiss Side says: Lighter, stiffer, faster, and even lower drag – the full carbon Hadron Ultimate makes a further step in speed on the already widely acclaimed and award winning original Hadron aero wheels. Using the latest in aerodynamic and engineering development methods transferred from Formula-1, the Hadron Ultimate sets new benchmarks for aero wheel performance. Ceramic bearings and tubeless ready construction as standard, and also available in disc brake versions.


– QR Skewers.

– High pressure reinforced rim tape with Swiss Side logo print.

– Spare / replacement spokes.

– Swiss Side stickers, product information & warranty cards


– The maximum permitted rider weight for this wheel set is 105kg.

– Tyre pressures of 120psi should not be exceeded.

Tell us some more about the technical aspects of the wheel?

Weight (claimed): Front = 708g, Rear = 881g, Set = 1589g

We weighted them as follows: Front = 698g, Rear = 873g. Includes rim tape (supplied fitted) but not QRs.

Rim depth: 62.5mm

Max rim width: 27mm

Width across brake surfaces: 23mm

Spokes: Sapim CX-Ray Straight pull. 16 x radial at the front, 21 x 2-cross 2:1 at the rear

Hub body: CNC machined 6061-T6 aluminium

Hub width: 100mm front, 130mm rear

Bearings: Enduro ceramic hybrid ABEC-5 grade

Rate the wheel for quality of construction:
Rate the wheel for performance:

Mostly good news. Outright speed and stability in the wind are both excellent. Braking (with the pads supplied) is effective, but makes an awful noise that no amount of toeing-in could cure. The stock pads were toast in 500 (hilly) kilometres. With quality SwissStop pads braking is significantly better. A bit of a question mark over rear-wheel lateral stiffness.

Rate the wheel for durability:

I've run other Swiss Side wheels for extended periods and had no issues – no reason to expect otherwise here. Stock brake pad durability is atrocious, so you'll want to get some better pads included if you can.

Only other quibble is that truing the wheels is a faff due to the internal nipples – even more so if you are running tubeless tyres.

Rate the wheel for weight

Very good for the rim depth.

Rate the wheel for value:

The Hadron Ultimates cost a good chunk more than the hybrid alu/carbon wheels we've tested previously from Swiss Side. In terms of aerodynamic and weight advantage per pound, I think they're arguably less good value than other Swiss Side competition, but there's no doubt that they stack up well against other leading big-brand aero wheelsets.

Did the wheels stay true? Any issues with spoke tension?

No issues.

How easy did you find it to fit tyres?

No problem. I didn't have any tubeless tyres to try.

How did the wheel extras (eg skewers and rim tape) perform?

All fine.

Tell us how the wheel performed overall when used for its designed purpose

Pretty similar to the alu/carbon Hadron 625 wheelset we tested (and liked a lot); the Hadron Ultimate is lighter thanks to the full-carbon construction. Aerodynamic performance appears excellent and the crosswind stability is really excellent for this rim depth. Inevitably braking suffers as a consequence of the switch to carbon – outright braking performance is acceptable with the stock pads, but the accompanying shriek is so unpleasant as to incline one to try to avoid braking wherever possible. Replacing with quality SwissStop pads fixed this.

Tell us what you particularly liked about the wheel

The combination of aero-assisted speed with really superlative crosswind stability. The lower weight (compared to the Hadron 625) is welcome, and they look and sound fantastic.

Tell us what you particularly disliked about the wheel

Braking with the stock pads, the accompanying noise and shocking pad wear rates. Brake rub on the rear wheel when pedalling out of the saddle. I'd have preferred external nipples to make truing easier.

Did you enjoy using the wheel? Yes

Would you consider buying the wheel? Yes

Would you recommend the wheel to a friend? Yes

Use this box to explain your score

Performance is excellent and they're a good bit lighter than the equivalent Hadron. I don't think they're as strong a value proposition, though – the price jump for full-carbon rim construction is significant, and braking (even once I'd changed the pads) isn't a match for an aluminium rim.

Overall rating: 8/10

About the tester

Age: 37  Height: 188cm  Weight: 78kg

I usually ride: On-one Bish Bash Bosh  My best bike is: Rose X-Lite CRS

I've been riding for: Over 20 years  I ride: Most days  I would class myself as: Expert

I regularly do the following types of riding: road racing, time trialling, cyclo-cross, commuting, touring, club rides, sportives, general fitness riding, fixed/singlespeed, mountain biking

Jez spends his days making robots that drive cars but is happiest when on two wheels.  His roots are in mountain biking but he spends more time nowadays on the road, occasionally racing but more often just riding. 

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