3T Discus Plus C25 Pro wheelset

With its bold Exploro aero gravel bike, Italian company 3T has been a big proponent of large volume tyres on 650B wheels for road and gravel. These Discus Plus C25 Pro tubeless-compatible wheels are 3T's cheapest aluminium wheels in this wheel size. Performance is very good, with impressive reliability and easy setup and, but the price is high compared to some of the competition.

Pros: Reliable, durable, easy tubeless, wide compatibility
Cons: Expensive compared to competition

For decades, two wheel sizes dominated: 700C for road bikes, and 26 inch for mountain bikes. In the last few years 650B, an almost-disused French standard, has enjoyed a resurgence. In the mountain bike world it has replaced the 26-inch wheels used since the good old Repack days, and more recently has made a dent on the decreasingly conservative road cycling market.

The important dimension here is the size of the rim, measured at the point where the tyre bead sits. For a 700C wheel the bead seat is 622mm across; for a 650B its 584mm. The rim being smaller means you can use a fatter tyre and end up with the same rolling diameter. The bigger volume provides extra cushioning to iron out rough roads while the similar rolling diameter means the bike's geometry can be the same as if it had 700C wheels and smaller tyres. A bit of smart design means some frames can use either 650B wheels with fat gyres or 700C with skinnier rubber.

We're increasingly seeing 650B being offered by bike manufacturers under the loose tag of 'road plus', suggesting they're good for road riding plus a bit of dirt and light gravel on the side. Of course, if your bike has the necessary clearance, there's no stopping you fitting a narrow mountain bike tyre for really rough off-road riding, and there's plenty of that taking place.

All that said, the 3T Discus Plus C25 Pro wheelset is a really good choice if you do want to go down the 650B route for mainly road riding or a bit of gravel-bashing too. The aluminium rims are 30mm externally with a 24mm internal width which plays well with wide tyres and ensures compatibility with up to 2.1in tyres. I tested them primarily with WTB Horizon 47mm tyres and the wide rims provide good support of a tyre of this size, with minimal squirm or roll even at lower pressures.

The rims are tubeless-compatible. I always get a frisson of apprehension when I install a tubeless-compatible tyre and starting stoking the track pump, but happily, the tyres inflated at the first time and pressure retention has been excellent. With a good glug of sealant in each tyre, they have sailed through all manner of conditions and road and trail surfaces with no (touch wood) punctures to report.

The hubs use Shimano's Center Lock disc rotor mounting system, and boy does it save a lot of time fixing the rotors in place compared with fiddling about tightening six bolts. The wheels come with adapters for six-bolt rotors as well. The hubs are also compatible with both thru-axle and traditional quick release axles, and 3T neatly provides a range of adapters. The end caps come off with no tools required making setup a doddle.

The freehub is Shimano and SRAM 10/11-speed compatible, but you can swap to a SRAM XD or Campagnolo freehub as an aftermarket option if you wanted to go down that route. There is an increasing range of Shimano compatible wide-range cassettes now available that probably covers most requirements.

Lacing the hubs to rims are 24 double-butted, straight-pull stainless steel spokes in each wheel. Asymmetric rim drilling is claimed by 3T to reduce the difference in spoke tension between the driveside and non-driveside. To try and ensure as straight a spoke as possible, the spoke holes have 'double angle drilling' which is designed to better align the spoke with the hub flange, while the alloy nipples sit in a washer for better alignment.

I can determine no change in spoke tension between the wheels arriving and inspection after several months of riding. Despite taking quite a battering on my rough potholed roads and a few excursions into the woods, the wheels are still running true with no hint of a warp or buckle.

When it came to riding the wheels, with the 47mm Horizon tyres inflated to about 40-45psi for my 65kg weight the bike rolls along my bumpy Cotswolds roads with all the comfort of a well-worn sofa. I strongly recommend experimenting a lot with tyre pressure, don't simply set and forget. The tyres are able to soak up a lot of the small chatter, knocking out vibrations before they get to the handlebars and saddle, as well as coping with bugger impacts, say if you accidentally ride into a pothole or sunken manhole cover.

A nice trait of the bigger tyres and smaller wheels is that the handling of the bike is very similar to a regular 700C-wheeled bike, but the stability feels enhanced. It takes more energy to knock the bike off its line and it's not easily unsettled on very fast descents with coarse road surfaces. And the comfort is grand too: it's like double wrapping the bars and wearing a second pair of padded shorts.

The rolling efficiency of the big tyres is impressive too, but there's a noticeable increase in power requirement above about 35kph. Curb your enthusiasm and settle down to between 25-30kph and they feel no slower than a 28mm tyre on a 700c rim, but with all the wonderful extra comfort.

You're probably thinking you should rush out and buy these wheels. Well, as much as I can recommend them, and even though they are 3T's entry-level offering, the £850 price tag definitely feels a bit steep. There's a more expensive carbon version if you're feeling flush, though the weight saving might isn't all that impressive. You get a deeper rim, 28mm versus 21mm, so they should be more aero if that's important to you.

The road.cc review team hasn't yet reviewed many 650B wheelsets, so it's hard to offer many useful comparisons. There are the Reynolds ATR2s (£1,299) that Dave tested earlier this year, but you have to pay a substantial wedge of cash extra for a small return on performance. As Dave points out, any impact resistance and vibration damping benefits of carbon rims are made a bit irrelevant by the simple fact you're running a large volume tyre at low pressure. Still, they do serve to make the 3T wheels look better value.

But then your cast your eye over the Hunt range and — well. Hunt has recently launched the AdventureCarbon Disc wheels, weighing a claimed 1,425g and with an internal rim width of 24mm, for £879. That does make the 3T wheels look expensive.

There are cheaper options too, like Hunt's 650B AdventureSport Disc wheelset at £319. Now, we haven't reviewed these wheels (yet) but on paper, the 1,549g weight looks competitive. The 20mm internal rim width isn't quite as generous as the 3T wheels, though, and wider really does work better with fat tyres.

To conclude then, the 3T Discus Pro wheels have been ultra reliable and durable, with easy hub and disc rotor setup, and tubeless compatibility so easy even the most retro grouch cyclist could ditch the inner tubes and embrace the future. If you want to get on the 650B bandwagon and have the clearance in your bike to accommodate them, there's a lot to like here, except that high price tag.

Verdict

Solid and dependable Italian 650b wheels with wide tyre support, but a bit spendy