3T Exploro Pro GRX 2020

The 3T Exploro Pro GRX is an excellent gravel bike that's focused on aero efficiency, and this is the first complete bike in the range to be specced with a Shimano groupset. With loads of tyre clearance, it offers plenty of comfort and control to go along with its speed.​

3T unveiled the Exploro, designed by Gerard Vroomen (the co-founder of Cervélo who has gone on to design bikes at Open as well as at 3T), back in 2016, calling it "the world's first aero gravel bike". Fusing different genres can be chancy. You might end up with something cool like salted caramel popcorn, or you might end up with something hideous like a liver trifle. Thankfully, when we reviewed the 3T Exploro Ltd frameset here on road.cc we found that it was – and it remains – a triumph.

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Since then 3T has added complete bikes to the range, two of them built around the Exploro Pro frameset which is a little heavier than either the original Ltd or Team models. Featuring new GRX components, this is the only Shimano-equipped Exploro in the lineup.

Right, that's enough context, how does this thing ride?

The ride

You get gravel bikes that owe a lot to mountain bikes – like the Merida Silex+ 6000 that I reviewed last month, for example – and you get others that are a lot more roadie. The Exploro Pro GRX falls into the latter category. It might not be all about speed, but it's a lot about speed.

When I reviewed the Exploro Ltd I said that it was a blast on gravel, or whatever fairly well-surfaced, fairly well-drained tracks you have around your way. The Exploro Pro GRX is the same. It's at its best when you can get down on the drops, wind up the power and hold it there, so its favourite environment is open terrain with empty tracks that roll off into the sunset – but, failing that, it'll settle for anything that's reasonably solid! It feels great when you crank up the speed.

> Is a gravel/adventure bike all you need?

The Exploro Pro GRX responds well to increased effort – even though it's 1kg heavier than the built-up 3T Exploro Ltd that we reviewed back in 2016 – and shifts line easily with changes in body position to dodge the biggest, deepest-looking puddles. When things get technical, the steering is lively enough for plenty of manoeuvrability, and 415mm chainstays keep the wheelbase short for a bike of this kind. Overall, if you put the 37mm-wide tyres to one side, the handling is similar to that of a road bike.

I've been riding this bike in January and February and even well-maintained stone and gravel roads have been soaked through, so rather than singing along on the surface, it has largely been a case of ploughing through the stodge. As for those bridleways that are muddy at the best of times, they've been more like marshland.

Tyre selection becomes a big issue in conditions like these and the WTB Riddlers fitted to the Fulcrum Racing 700 wheels have provided good grip on anything relatively firm, even through tight corners where you think they might not cope. They're also reasonably quick on tarmac; you don't really feel that you're being held back too much compared with road bike tyres.

The Riddler is a great tyre for a bike that's likely to spend its life on a mixture of tracks and tarmac, but if you veer onto anything muddy you have to start riding a bit more gingerly (I'm talking about good old sloppy mud here, not compacted earth which isn't a challenge), staying seated on steep climbs so that the back wheel doesn't spin, for example. The central tread is shallow and can struggle to grip into anything too deep.

If you want to fit different tyres depending on the conditions, there's enough clearance to go up to 40mm wide on these 700C wheels, or up to 54mm (2.1in) if you switched to 650B wheels.

The dropped driveside chainstay helps provide the space without making any difference to the way the bike feels.

Geometry

All versions of the 3T Exploro frame are built to the same geometry, one that's tailored towards fast riding. You, as the rider, have a much larger effect on aero efficiency than any tube shaping or smart frame features (more on those in a mo), so an aggressive setup makes sense on a bike like this.

I've been riding a large sized Exploro Pro GRX with a 571mm top tube, a 518mm seat tube, and a short 150mm head tube. Both the head tube angle and the seat tube angle are 72.5 degrees.

The stack height is 575mm and the reach is 390mm, giving a stack/reach of 1.47. That's road bike territory, but bear in mind that the Exploro comes with an inline seatpost – the clamp sits directly over the centre of the post without any layback – and that shortens things up. In other words, the distance from the saddle to the handlebar is less than the stack and reach figures might suggest.

It's still a speed-orientated geometry, though. If you're coming from a road bike background you'll probably get along with this position just fine. You can easily get into a low 'attack' position down on the drops when you want to push the speed, and even when you're sitting up on the hoods you don't feel like the wind is hitting you full on your chest.

On the flip side, if you want an upright, mountain bike-style position for tackling more technical terrain, that's not what's on offer here. You can't have everything!

Also, while we're talking about positioning, the 3T Superergo PRO handlebar measures 44cm centre-to-centre on the medium, large and XL sized Exploro Pro GRXs; there's none of the flare (where the drops angle outwards from the hoods) that you get on many gravel bars, including 3T's own Superghiaia design.

I must say that I've become partial to a bit of flare lately, the wider stance making for easier control over tricky terrain, and I missed not having it. Admittedly, adding extra width wouldn't be the best option in terms of aero efficiency.

Frame features

The Exploro Pro boasts all of the aero features found on other models in the range, meaning that it has what 3T calls Sqaero tube profiles. The leading edge and sides are designed for aerodynamic efficiency while the back is squared off, the idea being that the airflow behaves largely as if the profile had a long, tapering tail. Other brands follow the same principle. As well as reducing drag, this profile is designed to provide strength and stiffness without making the frame too difficult to handle in crosswinds.

You might not associate wide tubes with aero efficiency but 3T says the down tube has to be 50mm wide 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 all 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 30mph (48km/h) it would be a saving of 24 watts.

3T reckons that you still get the aero benefits when the bike is caked in mud – and if you live in the UK, it's probably going to spend a lot of time that way.

The gear cable and the hydraulic brake hoses are routed internally 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 also want to attach a bottle cage to the seat tube. If you're installing just one, the lower position results in less drag.

You also get two attachment anchors for a top tube bento box, but there are no rack or mudguard eyelets. 3T reckons that these days people are more likely to choose frame bags for weekend adventures.

One other frame feature that's worth mentioning is the Hang Loose rear derailleur hanger. You'd better be ready for this one or you'll think that your bike is falling apart the first time you drop the rear wheel out.

Essentially, the rear derailleur hanger comes away when you remove the wheel's thru-axle, the idea being that it makes re-installing the rear wheel easier later on. You put the rear wheel in position and get the brake rotor alignment right, then you install the thru-axle to stabilise the wheel before installing the Hang Loose hanger. It sounds complicated but it's actually very simple.

The same can't be said of the clamp on top of the seatpost. If you want to alter the angle of your saddle you have to take it off completely and change the position of two interlocking rings, then put everything back together and judge whether you've got it right. It's quite an intricate operation although, once set right, it's never going to move.

Shimano groupset

The Pro GRX is the first – and currently the only – Shimano-equipped Exploro in the range, the other five complete bikes all coming with SRAM components of one kind or another. This isn't surprising given that SRAM was quick to jump on board the gravel train while Shimano was a whole lot more circumspect, announcing its gravel-specific GRX lineup less than a year ago. 

> Check out our complete guide to Shimano’s GRX gravel groupset

GRX comes in three different flavours (although you can't buy all components in each of them) and you get the lot here: the rear derailleur is top-level GRX 800, the shift/brake levers and 40-tooth chainset are mid-level GRX 600, and the hydraulic disc brakes are entry-level GRX 400 (although they have resin rather than ceramic pistons, there's not a whole lot of difference between these and the more expensive GRX 800-level brakes).

GRX doesn't include cassettes. Instead, these are borrowed from elsewhere in Shimano's range, in this case from the SLX mountain bike groupset. It's an 11-42-tooth option (42-tooth is the maximum sprocket size that Shimano suggests with GRX).

The 40x11 combo (with the 700x37mm tyre fitted here) gives you a top gear of just under 100in, while the 40x42 low gear is just over 26in. That's small. It'll allow you to get the unladen Exploro Pro GRX up pretty much anything without your quads twanging. Load the bike up with bags and head off for an adventure and you'll still get up most climbs that you're reasonably going to tackle – not fast, admittedly, but eventually.

To put that gear range in a roadie context, a 50/34t chainset and 11-30t cassette, with a 700x28mm tyre, would give you 30in to 121in – so you don't get the high gears on the Exploro Pro GRX. In truth, you do sometimes feel undergeared on the road, your cadence hitting 100rpm in 40x11 before you get to 30mph, but it's unlikely to be an issue on tracks where speeds are generally slower.

I won't go into any great depth on GRX here because we've reviewed it extensively elsewhere, but the rear derailleur worked flawlessly throughout testing, the dual control levers were comfortable both when resting on the hoods and during braking, and the brake callipers (now flat mount) functioned exactly the way you'd want them to. It's impressive stuff.

Money bit

We've not tested many four grand gravel bikes previously on road.cc, although the Pinarello Grevil that Stu reviewed last year was £4,500.

The Grevil is similar to the Exploro in having a carbon fibre frame with aerodynamic tube sections and an aggressive geometry, although our test bike was fitted with a Shimano Ultegra 50/34t chainset and an 11-32t cassette – which is what you might expect to see on a road bike. The Grevil had the same Fulcrum Racing 7 DB wheels as our Exploro (Racing 7s and Racing 700s are exactly the same apart from the graphics), albeit in a 650B size.

> Buyer's Guide: 22 of the best gravel & adventure bikes

The Salsa Warroad that we reviewed was £3,750 – a bike designed to be capable on the road, on gravel and everything in between. It had a Shimano 105 groupset, WTB wheels and 47mm WTB Byway tyres.

The 3T Exploro offers better value than either of these bikes, although you could get the Grail CF SL 8.0 Di2 from Canyon – a brand with a direct-to-consumer business model – for £3,149.

Conclusion

You might not be convinced of the benefits of an aero gravel bike, but ride the 3T Exploro Pro GRX and it will win you over. This bike can certainly handle more technical terrain, but it really shows its worth when you're riding at speed, and it crosses over to tarmac without missing a beat. If you're after a bike for fast-paced gravel riding, including events like The Dirty Reiver and Gritfest, the Exploro is hard to beat.

Verdict

Quick and lively aero gravel bike with plenty of tyre clearance and Shimano's GRX components