3T Exploro LTD frameset

The 3T Exploro is an agile gravel bike with aero features and masses of clearance, although the price puts it out of reach of most of us.

3T boasts that the Exploro is the world's first aero gravel bike. You can file that under 'groundbreaking' or 'madness', depending on your point of view. We'll come back to that issue in a bit. First, though, I'll tell you about the ride.

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The Exploro is an absolute blast on gravel. If you have fairly well surfaced, fairly well drained tracks around your way, you're in for a treat. This is a bike that allows you to get your head down and crank the speed up high. That's when the Exploro is at its best – when you're pinning it across rough but firm roads. It flies across that stuff faster than any other gravel bike I've ridden.

Head onto muddy bridleways and it's still a very capable performer, the proviso being, as it is with any other bike, that you fit the right tyres. The Exploro has plenty of clearance – masses of it, in fact. Our review frameset came fitted with 650B wheels and 47mm tyres although you could go up to 54mm (2.1in) with these wheels or 40mm with 700C wheels.

We had smooth WTB Horizon tyres on our review bike and they don't really bite into soft ground so any type of steep, wet climb was a challenge but, on the other hand, they're excellent on gritty tracks. Swapping tyres according to the terrain you ride and the conditions is obviously simple enough.

When things get technical, the steering is lively enough for loads of manoeuvrability. The Exploro is quick to respond when you need to change your line to avoid dips and bumps, and tight corners really aren't a problem. Short chainstays (415mm) keep the wheelbase short for a bike of this kind, so the handling is similar to that of a road bike.

Of course, the Exploro isn't going to keep pace with a mountain bike through lumpy, bumpy singletrack, but you wouldn't expect it to because of the lack of suspension and a much narrower handlebar. You just have to take that kind of stuff at your own pace. But once things open up again and you hit straighter, smoother stuff, the Exploro will leave a mountain bike coughing and spluttering in its dust.

If you're lucky enough to have gravel roads within riding distance of your door, chances are you're going to have to spend some time on tarmac getting to them. The Exploro behaves like a road bike on tarmac – a road bike with massive tyres. In terms of geometry (I'll come back to that), weight, feel and stiffness, you'd do well to notice much difference. Wide tyres squish from side to side when you get out of the saddle but the massive BB386Evo bottom bracket stays resolutely in place when you sprint or climb.

As an experiment, I did one of my standard tarmac rides on the Exploro as fast as I could and the speed was very similar to what I'd expect on a standard road bike. I know it's anecdotal – you don't need to point that out – but we're talking about a fraction of a mile in an hour, and that's on a bike with 47mm tyres and disc brakes. I was stunned. I didn't find it to be as quick as the quickest road bikes, but it certainly doesn't hang around or feel unsuitable when you hit the asphalt, so for multi-surface adventures it's a very willing and able companion.

Aerodynamics

So, the Exploro is the world's first aero gravel bike, huh? In the words of many a bad stand-up comedian, what's all that about?

We can't say we heard much of a clamour for an aero gravel bike, but that doesn't mean it's an iffy concept. 3T's argument is that aerodynamics matters even at low speeds. 'Go slow faster,' it says.

With that in mind, the Exploro features what 3T calls Sqaero tube profiles, which essentially means you get a leading edge designed for aerodynamic efficiency with a square rear section, the idea being that the airflow behaves largely as if the profile had a long, tapering tail. As well as reducing drag, this profile is designed to provide strength and stiffness without making the frame too difficult to handle in crosswinds.

Chunky tubes are a familiar part of the bicycle landscape these days, but the Exploro's down tube really is something special. The road.cc vernier callipers say that it's 50mm across while the seat tube is 25mm wide.

We don't usually associate wide tubes with aeroefficiency but 3T says that the down tube has to be so large to manage the airflow coming off a wide front tyre and lead it on to the water bottles. The idea is that the seat tube 'aerodynamically disappears' between the bottles and the rear tyre. The head tube, seatstays and seatpost use Sqaero profiles too.

The result of all this aero shaping, according to 3T, is that at 20mph (32km/h) the Exploro saves 7 watts over a round tube frame with the same tube widths, the same frame details and the same components. At a less realistic 30mph (48km/h) it would be a 24 watts saving, 3T says (3T is going to publish a white paper on the aerodynamic technology, by the way, that you can request here). Those are significant differences if you're racing.

> Read our buyer's guide to gravel and adventure bikes

What about if you're just going out for a tear up with your mates? Are you likely to ride at 20mph on gravel? That's going to depend on your fitness and the type of terrain you ride, but it would be pretty damn quick on the rolling, pockmarked gravel roads around my way. The advantage the Exploro offers over a non-aero bike is going to be small at lower speeds, getting larger the faster you go. That's certainly the way it feels to me. As I said above, the Exploro is at its best when you're bowling along in a big gear.

Anyway, check out the white paper for yourself as soon as it's published and see if you're convinced. By the way, 3T reckons that the aero benefits hold true even when the bike is caked in mud – and, let's face it, if you live in the UK, it's going to spend a lot of time that way.

Other frame features

The Exploro's designer, Gerard Vroomen – formerly of Cervélo – wanted the Exploro to have a road bike's Q factor (the distance between the pedal attachment points), and with clearance for such wide tyres that didn't leave much space for chainstays. For that reason he put a drop in the driveside one to move it out of the way, as he did on his Open UP design. It makes no difference at all to the way the bike feels.

The gear cable (singular; our review bike is set up with a SRAM Force 1 system) and the hydraulic brake hoses are routed internally. Although it wasn't the tidiest execution on our review bike, you could get everything set up very neatly yourself via the FlipTop cable guide on the top tube. This comes in different versions for mechanical and electronic shifting, and single and double chainsets. 3T uses full cable housing through the frame for mechanical shifting to keep the cables protected from dirt.

You can choose between two bottle cage positions on the down tube, although you need to opt for the upper one if you want to attach a bottle cage to the seat tube as well. If you're only installing one, the lower position is the more aerodynamically efficient option. You also get two attachment anchors for a top tube bento box, but there are no rack or mudguard eyelets. 3T thinks people are more likely to choose frame bags for weekend adventures.

One other frame feature that's worthy of mention is the Hang Loose rear derailleur hanger that's designed to make re-installing the rear wheel easier. You first replace the rear wheel and get the brake rotor alignment right, then you install the thru axle to stabilise the rear wheel before installing the Hang Loose hanger. It sounds complicated but it actually makes setting things up a doddle.

Geometry

The Exploro's geometry is intended to be tailored towards both fast and comfortable riding – closer to a road or cyclo-cross position than to a mountain bike position. Your riding position is always going to make more difference to your overall (bike and rider) aerodynamics than any clever tube shapes or frame features, so it makes sense for 3T to offer an aggressive setup here.

We have a large sized model in for review. It comes with a 572mm top tube, a 518mm seat tube, and a short 150mm head tube.

The stack (the vertical height between the middle of the bottom bracket and the top of the head tube) is 576mm and the reach (the horizontal distance between those points) is 390mm. Bear in mind, though, that the dedicated seatpost has an inline clamp, and that shortens things up compared with a layback seatpost.

If you can't be bothered with the numbers, the upshot is that the riding position is a little more upright than that of a standard road bike, but not by a long way. Chances are you'll get along with this position just fine if you're from a road bike background. I did. I like to get low and purposeful even when riding rough stuff, and I could do that here. Plus, this position is a real boon when you're on the asphalt – and, let's face it, few of us are going to ride a gravel bike solely on gravel.

Options

For the record, our review bike came built up with a SRAM Force 1 groupset with hydraulic disc brakes (post mount rather than the flat mount standard that has become dominant) and a THM Clavicular SE carbon chainset. The wheelset is 3T's own aluminium Discus Plus C25 Pro 650b with WTB Horizon tyres. That's all academic, though, because the Exploro is sold as a frameset.

In fact, it's actually sold as two different framesets. They're out of the same mould but the carbon fibre differs. The Team version weighs a claimed 1,150g and is priced at £2,400 while the LTD model that we have is a claimed 950g and it's priced £3,360.

Summing up

Some people might consider 'aero gravel' to be a niche too far, but the 3T Exploro is an innovative bike that's at its best when you're riding fast over solid or at least firm tracks. It's never going to have mass market appeal, especially at this price, but this would be a great bike for gravel racing, taking on a gravel/cyclo-cross/multi-surface sportive (there are a few around these days), or just getting away for a fast-paced adventure. The Exploro is agile enough for the technical stuff too, it's just that it really shines when you crank up the pace.

Verdict

Aero gravel bike that's fast and agile, but the price... Ouch!