Ultra Boost



You can ride the Ultra Boost just like your standard Ultra tough-gravel bike, only expanding your horizons.

Ultra Boost Urban have the same capabilities of Ultra Boost, just with a more upright position, ideal for commuting or granting additional control.


Review after review and award after award raves about the light, responsive & fun ride of the Exploro Ultra. So when it came time to make an e-bike version, we didn’t want to change anything: same geometry, same aero tube shapes, same agile steering.

But thanks to the e-bike system that hides inside, you have some extra power at your fingertips. Take that detour, climb that mountain or simply have a "no-sweat commute" to work and a great workout on the way home.


We love riding our Ultra into the unknown. Every mountain peak conquered is the result of your own effort. Still, we sometimes wonder what lies beyond that last peak and the extra Boost helps us find out.

Others may love to ride with a group of friends but don’t want them to wait up at the top of the climbs. A little extra Boost lets you arrive all together.

Or maybe you love to commute to work but want to arrive fresh. The Boost lets you get to the office without a sweat and enjoy an adventurous workout on the way home (after all that’s a lot more time-efficient than driving and having to hit the gym afterwards).


All Ultra Boost & Ultra Boost Urban models come equipped with Mahle X20 system: 55Nm of torque, 350wh battery that offers additional Boost to your legs and helps keeping the weight down with the complete Ultra Boost complete bikes starting at approximately 12kg (Ultra Boost Urban Force AXS w/i28 carbon wheels model, size 54, no pedals).

The Mahle X20 system offers BT and ANT+ connectivity (Garmin ready), 3 Ultra Boost & Ultra Boost Urban specific “default power modes” + a 4th mode, fully customizable though MySmartBike app.

With a relatively gentle power management, it’s easy to reach more than 150km and 2000m of elevation*

If you need even more battery range, a 173Wh Mahle battery extender (just 1.1kg to be installed on the seattube’s bottle cage) can be purchased separately, increasing the bike range by 50%

*average for a rider below 75kg, on a hilly fast gravel/paved route, considering EU 25kmh speed limit


To make the fastest possible gravel bike, you need to start with the tires. Tire choice determines comfort & grip, but it also determines how you can shape the frame to redirect airflow.

To aerodynamically engineer the frame around the tires, you need to know what their REAL measurements are. Not what’s on the label, but how they really fit. That’s REALFAST aerodynamics. It’s not easy however, as the tire dimension depends on the rim you use, tire pressure, and of course how accurate the manufacturer’s claimed size is.

We took hundreds of measurements to know the real tire widths (which we call WAM - Width As Measured and RAM - Radius As Measured) and engineered the frame around that data.

Max clearance information can be found here.


The Ultra was our most difficult aerodynamic challenge to date. Start with massive 55-61mm tires and then make the bike aero. There’s nothing we can do about the tires, they’re big and the knobs don’t help. What we can do is take the airflow mess that comes off the front wheel and try to catch and redirect it. That’s why you will see the 60mm wide downtube placed closely behind the front wheel, going even wider as it gets closer to the BB. 

Blending this into the headtube with an off-center aero profile along with loads of other tricks gives you a bike that feels so much faster than your brain can compute. Because let’s be honest, when you see those tires, your brain gets ready for that slow, boring paved performance of a mountain bike. But thanks to your riding position, the aerodynamics, the BB stiffness and the narrow Q-factor, the Ultra actually feels 100% like a road bike when you want to go fast. Even when muddy.

Urban version offers all the above features blended with a carbon flatbar for a more upright position (perfect for commuters or just more relaxed rides) or just even more control where the path becomes tough.

design in details


Standard frames require an adaptor to use a 160mm brake rotor. We have integrated that into the frame, meaning you don’t need any extra pieces to attach the brake.


Standard forks require a flip-flop adaptor to set the correct brake rotor size. Our direct-mount pre-sets the caliper for 160mm rotors without any extra pieces.


Self-adjusting bolt angle for higher clamping forces with lower torque.


The seattube is kept aero yet it fits a round 27.2mm seatpost so you have many round, dropper or suspension post options.

Size 51 54 56 58
Rider Height (cm) 157-171 168-180 176-186 183-195
Rider Height* (inches) 5'2"-5'7" 5'6"-5'11" 5'9"-6'1" 6'0" 6'5"
Stack 544 566 586 606
Reach 364 374 382 390
"Road" Headtube 147 161 180 201
Headtube angle 69.2 70.7 71.7 72.2
Fork axle-crown 375 375 375 375
Front center 612 607 612 622
Rear center 418 418 418 418
BB drop 77 77 75 73
Wheelbase 1018 1013 1019 1028
Toptube lenght 518 536 549 563
Seattube lenght 463 490 518 545
Seattube angle 72.5 72.5 72.5 72.5
* Rider heights are approximations. Please note the choice between a Flatbar or Dropbar bike may affect your fit. For more accuracy, compare stack/reach with your current bike or visit your 3T retailer. ** Ultra FORK length is equal to a standard road bike, so this HEADTUBE length can be compared to road bikes. To compare to gravel bikes with standard gravel forks, deduct 25mm from these “road" headtube lengths for a proper comparison.