Flat bar and MAHLE Ebikemotion motor – 3T aim to turn the Exploro Boost Flatbar into an all-purpose weapon, blurring the boundaries between urban and gravel bikes. Can the Italian brand’s first ebike perform as an urban explorer and gravel bike in equal measure? We’ve put it to the test to find out.

3T Exploro RaceMax Boost Flatbar | MAHLE Ebikemotion X35+ | 12.02 kg (size 54) | € 6,999 | Manufacturer’s website

Urban and gravel seem to be worlds apart, both geographically and in terms of the mindset and requirements for the perfect bike for the respective terrain. 3T have tried to join these seeming opposites with the Exploro RaceMax Boost, equipping the Exploro RaceMax frame with the MAHLE Ebikemotion X35+ motor and an optional flat mountain bike handlebar. What is the idea behind it? According to 3T, the bike is intended for three use cases: the electric drive is meant to allow you to ride farther and experience more than you can without assistance. It’s also meant to provide the support to keep up with stronger riders on group rides. The third use case is commuting – getting to the office in the morning with electric assistance, without breaking a sweat, and then turning off the motor on the way home to complete the workout on the gravel trails. In addition, the optional wide flat bar should offer an upright sitting position and more control. It will also appeal to riders who are unfamiliar with road bike handlebars. We tested the 3T Exploro RaceMax Boost Flatbar in size 54, weighing in at 12.02 kg and costing € 6,999. Below, we’ll give you the lowdown on the motor, components and handling.

Helmet Bollé REACT MIPS

The motor of the 3T Exploro RaceMax Boost: MAHLE Ebikemotion X35+

For the motor, 3T have chosen to rely on the proven MAHLE Ebikemotion X35+ system, as featured on the SCOTT Addict eRIDE Premium (review here) and the Orbea Gain M20i (review here), both of which you’ll find in our current road bike group test. The MERIDA eSILEX+ 600, which we’ve reviewed previously, also uses this motor. What sets 3T apart is that they’ve managed to integrate the components of the system into their existing 3T Exploro RaceMax frame. At first glance, the Exploro RaceMax Boost doesn’t differ from its siblings, driven by muscle power alone. The only things revealing the electronic assistance are the 250 W and 40 Nm hub motor in the rear hub, the charging socket under the bottom bracket and the iWoc ONE remote control on the handlebar. The PAS sensor is integrated into the freehub, which compares the motor’s revolutions with those of the cassette to work out whether you’re pedalling or not. The software then assists accordingly. This detour is necessary since the bike doesn’t have its own torque sensor to measure the rider’s input. In some situations, this means that the motor will offer its full assistance even if you’re just spinning the cranks without putting in any effort. This can feel like a welcome shuttle service, but it can be annoying and even dangerous when you’re navigating a tight corner or turning around. The sudden thrust can cause the bike to tip over when you’ve got the handlebar turned. Additionally, the motor’s response is somewhat delayed, which isn’t bad on long, monotonous journeys, but it can feel slow when you’re putting in frequent sprints. Otherwise, the motor kicks in gently and feels very natural up to and including the point at which it cuts out at 25 km/h.

The MAHLE Ebikemotion X35x engine sits in the rear wheel as usual.
The battery is hidden in the down tube.

You can feel the motor’s assistance most when riding in flat terrain, allowing you to maintain 25 km/h with little effort. If you ride any faster, you’ve got the additional weight of the drive unit holding you back. This ballast will slow you down on gradients that you could usually climb faster than 25 km/h. Accordingly, the preferred inclines of the Exploro RaceMax Boost are those on which you couldn’t reach 25 km/h without a motor. That said, this is the case with all ebikes. The motor’s assistance is somewhat lacking when pulling away from traffic lights. As such, the bike is more suitable to be used on bike paths than in traffic.

With the iWoc ONE remote, you can switch on the motor and toggle between the three support modes, which 3T and MAHLE have adapted for the Exploro RaceMax Boost. The lowest level is supposed to provide strong support when starting off to get up to speed, and then provide light support over the entire speed range to keep up with stronger riders. The medium mode is said to provide the extra power needed especially at typical climbing speeds, and the highest level is said to provide maximum support across all speed ranges. However, you can still adjust the support levels yourself via the MAHLE Ebikemotion app. The app also allows you to navigate routes and evaluate your riding data, including your power consumption. In the highest support mode, the 3T managed to transport our 70 kg test rider over a hilly, 20 km commute with 150 metres of elevation gain on one full charge. If you ride the bike with the motor switched off from time to time, as envisioned by 3T, you’ll achieve significantly longer ranges. To find out more about the topic of ebike range, check out the article we’ve published in our sister magazine E-MOUNTAINBIKE. The battery charging socket is located under the bottom bracket. Although it is awkward to reach and quickly gets dirty, it offers the possibility to attach an additional battery under the down tube and thus continue to attach two bottle cages in the frame triangle.

The 3T Exploro RaceMax Boost in detail

At first glance, the Exploro RaceMax Boost doesn’t differ from its siblings and you wouldn’t guess that it’s an ebike. We’re familiar with the frame itself, as we’ve already reviewed the Exploro Race in our most recent gravel bike group test. The head tube of the aerodynamically optimised frame has been kept as slim as possible by routing the cables externally around the head tube and only then entering the frame via the top tube. Is aerodynamic optimisation that important on a gravel bike, especially if it comes at the cost of unsightly cable routing? We don’t think so.

In contrast to the 3T Exploro Race, the Exploro RaceMax Boost has to make do without the bottle cage bosses under the top tube to make way for the iWoc remote. However, you can still mount a bottle cage both on and under the down tube, despite the integrated battery. Together with the bosses on the seat tube, you can transport a total of three water bottles. The standout feature of the 3T Exploro RaceMax Boost is the optional 690mm wide handlebar, which breaks down the barriers between bike genres. It is a visual statement that has the potential to inspire additional layers of buyers from graveling. Still, we’re glad 3T leave it up to the customer to decide whether they’d rather have a flat bar or a drop bar.

There will also be a 3T Exploro RaceMax Boost Ultralight which you can see in the gallery below. This bike is weighing in at just 10.9 kg and costing € 9,999!

Components and geometry of the 3T Exploro RaceMax Boost

The drivetrain of our test bike consists of Shimano’s mechanical 11-speed GRX derailleur and a 105 flat-bar shifter. The 40 t chainring and 11–42 t cassette offers suitable gear ratios for the speeds and topography for which this bike is designed. However, the shifting felt a bit spongy. The Exploro RaceMax Boost comes fitted with 160 mm rotors front and rear and Shimano GRX brakes, but we would have expected more than BL-RS600 brake levers. Although they offer sufficient braking power, they don’t match the other components in terms of look and feel. On the other hand, we were pleased about the direct-mount callipers. Moreover, the Pirelli Cinturato Gravel M tires form a good aerodynamic unit with the wide 3T Discus 45 | 40 LTD wheels, featuring a considerable 29 mm internal width.

Groupset Shimano GRX 800 1 x 11
Ratio 40 T x 11–42 T
Brakes Shimano GRX with BL-RS600 levers 160/160
Wheels 3T DISCUS 45wheels | 40 LTD
Tries Pirelli Cinturato Gravel M 700 x 35C
Seatpost 3T Charlie Sqaero Team
Handlebar 3T Carbon Flatbar LTD 690 mm
Stem 3T Apto Stealth 110 mm
Weight 12.02 kg size 54
Price € 6,999

The riding position aboard the 3T Exploro RaceMax Boost Flatbar is compact and very well-centred, making you feel at one with the bike. The flat bar means you sit a little more upright than on the drop bar equipped Exploro models. You can find all geometry figures in the table below.

Size XXS 51 54 56 58 61
Rider height 142–157 cm 153–167 cm 164–177 cm 175–185 cm 183–196 cm from 192 cm
Seat tube 436 mm 463 mm 490 mm 518 mm 545 mm 572 mm
Top tube 506 mm 526 mm 546 mm 566 mm 586 mm 606 mm
Head tube 125 mm 147 mm 161 mm 180 mm 201 mm 232 mm
Head angle 69° 69.5° 71° 72° 72° 72°
Seat angle 74.5° 74° 73.5° 73° 72.5° 72.5°
Chain stay 415 mm 415 mm 415 mm 415 mm 415 mm 415 mm
Wheelbase 998 mm 1,008 mm 1,008 mm 1,014 mm 1,024 mm 1,044 mm
Reach 355 mm 366 mm 377 mm 385 mm 393 mm 404 mm
Stack 520 mm 542 mm 564 mm 584 mm 604 mm 632 mm
Bottom bracket drop 79 mm 79 mm 77 mm 77 mm 75 mm 75 mm

The 3T Exploro RaceMax Boost Flatbar in review

The flat bar of the 3T Exploro RaceMax Boost has a decisive influence on the bike’s feel – from handling to comfort and safety to speed. Die-hard roadies will have to get used to it. In contrast to a drop bar, flat bars offer only one grip position, limiting the riding position. On the other hand, the flat bar makes it easier for newcomers to the gravel segment or those crossing over from the mountain bike sector. The Exploro RaceMax Boost Flatbar convinced us with its incredible composure and good straight-line stability on asphalt and compacted surfaces such as hard-packed gravel. However, the bike’s steering is very direct and responsive. It is likely to feel nervous for those new to the gravel scene, though experienced gravel rider will enjoy the bike’s manoeuvrability, especially in the urban jungle. Thanks to the wide handlebars, the direct handling of the 3T is easy to control, and if the worst comes to the worst, you can quickly correct and navigate corners with pinpoint precision. In rough terrain, the bike starts to get restless and skip over bumps. At this point, the otherwise excellent vibration damping reaches its limits, both at the front and rear. Larger bumps, roots or steps feel harsh. Pirelli’s minimum inflation of 3 Bar for the Cinturato Gravel M tires is a disadvantage here, especially for lighter riders. Lowering the tire pressure could make the bike a whole lot more comfortable. It is up to you to decide whether you want to adhere to the manufacturer’s specifications. Together with the hard grips, riding in bumpy terrain can quickly lead to sore wrists. However, the bike is more than comfortable enough on asphalt and smooth gravel.

The flat bar offers an upright riding position with the brake levers and shifter always within easy reach, instilling the rider with confidence – perfect for gravel beginners. Regarding speed, the Exploro RaceMax Boost Flatbar invites you to cruise rather than attempt to break any speed records. The wide tires and the upright riding position with your arms outstretched act like a parachute. Cruising in flat terrain with the assistance of the motor at the 25 km/h threshold? With pleasure! To ride any faster for sustained periods and thus not rely on the motor, you’ll need powerful legs. The same applies to easy climbs. However, since you’ll ride slower than 25 km/h on most climbs, the motor is usually more of an aid than a burden. That said, we see the use of the RaceMax Boost for training without motor assistance more for people who ride for fun than for ambitious athletes with a structured training plan. How much fun it actually is to move the extra weight of the drive is something everyone has to decide for themselves.

2 in 1: Gravel bike and commuter in one?

To come back to our initial question of whether the 3T Exploro RaceMax Boost Flatbar can perform as an urban explorer and gravel bike in equal measure: the bike has its compromises. The usually excellent gravel performance of the Exploro RaceMax frame suffers from the wide handlebars, which tend to put you in cruising mode. And the gravel-specific components don’t make the bike an ideal city commuter. Above all, the tires aren’t great on asphalt. Nevertheless, the bike has its place, and we believe it appeals to a very diverse target group. Those interested in gravel might be less put off by the flat bar, which drop bars do for some. For experienced riders, the bike can function as a nimble everyday commuter, ready to take on any terrain in and around the city. Due to the design of the slightly swept-back flat bar, it makes us think of a fixed-gear messenger bike, one on which you can use the motor’s assistance to cut through lines of traffic!

Our conclusion on the 3T Exploro RaceMax Boost Flatbar

The 3T Exploro RaceMax Boost Flatbar blurs the boundaries of bike genres and is intended to appeal to riders beyond the cosmos of drop bar gravel bikes. The wide handlebars certainly have the potential to do so. If you’re not after speed, preferring to cruise over asphalt or smooth gravel with wide handlebars and electric assistance, this is the bike for you. Drop bar fetishists and gravel racers, on the other hand, should rather choose the drop bar version.


  • works on gravel and in the city
  • good control due to wide handlebars
  • direct-mount 160-mm-brakes front and rear
  • light weight for an e-gravel bike


  • look and feel of the brake levers
  • tends to be nervous on demanding surfaces
  • limited comfort

For more information, visit 3t.bike

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Words: Photos: Tobias Hörsch & 3T