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ULTRA

THE UNSTOPPABLE MACHINE FOR THE TOUGHEST GRAVEL

If you’re like us, you love riding in rough terrain but live in a more urban jungle. So you need a bike that is fast on-road and capable off-road.

We designed the Ultra to fit 55-61mm wide tires: the whole aero package is made around those to keep the on-road speed high. If you ride on less extreme terrain, you can also fit 700c tires up to 45mm WAM (With As Measured) on the Ultra.

IT ALL STARTS WITH THE TIRE

To make the fastest possible gravel bike, you need to start with the tire. Tire choice determines comfort & grip. But it also determines how you can shape the frame to redirect the 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. But it’s not easy, as the tire dimension depends on the rim you use, the pressure and of course how accurate the manufacturer’s claimed size is.

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

SO WHAT TIRE DO YOU NEED?

The most important dimension is the WAM as that directly correlates to traction, puncture resistance, aerodynamics and rolling resistance. The WAM you need depends on three factors:

1. Terrain (traction, puncture resistance)

2. Rider skill (how much grip you need for control)

3. Rider speed (the slower you go, the more you bump/sink into the terrain)

The graph on the left indicates the WAM you need, and a more in-depth analysis can be found here.

Our favorite tires for the Ultra for each WAM and various rim widths are here.

Please note that running a front derailleur (especially an electronic version) will limit the tire width you can fit.

REALFAST AERODYNAMICS

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.

ULTRA VERSUS RACEMAX

The RaceMax frameset is is fastest with 35-46mm WAM tires. That’s when its top speed rivals the best road bikes out there. So whether you’re on asphalt, easy or tougher gravel, you can be sure you have the fastest setup. But depending on where you ride and how fast you ride, you may want an even bigger tire for ultimate traction and control. Good news: 90% of the aerodynamic advantage of the RaceMax frameset still works with tires up to 61mm WAM.

In a way, the Ultra is the reverse. It is aerodynamically optimized for 55-61mm WAM tires thanks to its wider downtube near the front tire. This extra width better redirects the air coming off a bigger front tire. If you prefer a smaller tire, you can run a 700c tire up to a 46mm WAM. But as you go to a smaller tire, the Racemax becomes the faster choice again. In addition, the Ultra combines its aero seattube with a round seatpost so you can fit a standard, dropper or suspension post.

design in details

GEOMETRIES

Size XXS 51 54 56 58 61
Rider Height (cm) 145-160 157-171 168-180 176-186 183-195 192 & up
Rider Height* (inches) 4'9"-5'3" 5'2"-5'7" 5'6"-5'11" 5'9"-6'1" 6'0"-6'5" 6'3 & up
Stack 520 542 564 584 604 632
Reach 351 362 373 381 388 399
"Road" Headtube 122 142 158 175 196 225
Headtube angle 68.5 69.5 71.0 72.0 72.5 72.5
Fork axle-crown 375 375 375 375 375 375
Front center 597 606 602 607 616 636
Rear center 419 419 419 419 419 419
BB drop 79 79 77 77 75 75
Toptube lenght 510 527 545 559 574 593
Seattube lenght 436 463 490 518 549 576
Seattube angle 72.5 72.5 72.5 72.5 72.5 72.5
* Rider heights are approximations. 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.