Frame sizing is something we leave entirely to our front triangles. Seat-tube length, reach, headtube length, and seat-tube angle are all handled solely by the foremost member of the chassis. Sure, every once in a while, a brand might use a longer chainstay for larger bikes, but the essence of the suspension remains exactly the same. The position of those pivots and the shapes of those members aren’t chosen arbitrarily. Changing them for each of, say, four different frame sizes would mean engineering four different bikes. Who on earth would do that?
Cannondale would. With the release of the all-new Habit, Cannondale introduces a concept it’s calling Proportional Response, a nod to a scene in Season 1, Episode 3 of “The West Wing.” The scene was about bold moves as opposed to cautious pragmatism, and the Habit’s approach is certainly bold. We spent the past two weeks passing a couple (two sizes’ worth) around while testing for the soon-to-hit-internet-and-newsstands 2019 Bible of Bike Tests, and you’ll be seeing our roundtable review of the Habit this December. But for now, we’ll cover a Cliff’s Notes version of Proportional Response in a moment as well as some of the other bold moves on the new Habit.
First, it’s gone to 29-inch wheels. When we rode the 27.5-inch Habit on the Kingdom Trails during 2016’s Bible in East Burke, Vermont, we found it to be a 29er in disguise. Something that would be well served by bigger wheels. This new Habit gives ’em to us. It also gives us an alternative to the Scalpel SE, which we tested earlier this year. Cannondale’s stab at aggressive XC, the Scalpel SE, is certainly more capable than the purpose-built stock Scalpel, but the compromises in geometry that came with adding 20 millimeters of front travel cost it some versatility. The Habit aims to be the multi-purpose, aggressive, lightweight trail evolution of those two platforms.
It’s also gone to a Horst Link. For the first time in its modern history, Cannondale is not using a single-pivot-suspension platform. One goal is to achieve the better pedal efficiency Horst Links are known for, but slightly more nuanced is its goal in addressing braking performance. The chainstay-mounted pivot of a Horst Link allows the rear suspension to stay more active under braking. But Cannondale is taking both of those a step further with Proportional Response.
At the center of Cannondale’s new approach is the rider’s center of gravity. The force we put into a bike doesn’t originate at the pedals. It gets there through the interaction between our body’s mass and the bike’s contact points. Points like where tires hit the ground, where our hands hit the handlebars and, of course, where our feet hit the pedals. Each of these points interacts in a different way on a different-sized bike and under different-sized riders. By slightly adjusting the Habit’s linkage, Proportional Response aims to achieve optimal efficiency regardless of rider size. It also adjusts the leverage curve for each rider, so there’s more than just heavier compression tuning and higher pressure keeping bigger riders in the right spot in the stroke.
These factors are also at play while braking. The position and direction of a rider’s center of gravity is different depending on his or her height. Cannondale claims that suspension performance under braking loads will vary for different sizes of riders unless that suspension takes those different sizes into account. In the Habit’s case, this means ensuring the suspension will be able to extend under braking forces rather than lock up.
What does that all mean? You’ll have to wait until the 2019 Bible of Bike Tests drops December 21st.