Canfield Brothers recently released details of its Canfield Balance Formula suspension patent. More than seven years in development, CBF is designed to deliver efficiency and performance via optimal anti-squat throughout the entire range of travel independent of "sag."
Utilizing the parallel link design that Canfield Brothers has been refining since the late 1990s, CBF is claimed to "balance" driveline forces by pointing them through the center of curvature, which the formula focuses in a very finite space on top of the chainring. The result an efficient yet active pedaling platform independent of sag, travel, and both drivetrain and braking forces. Check out the animation below to see the formula in action.
"Most suspension designs focus on the instant center," explained Chris Canfield, suspension expert and co-founder of Canfield Brothers. "They are only efficient in a very finite part of travel when chainline forces are balanced with that point, hence the reason for recommended sag."
Read our full review of the Canfield Brothers Riot 29er trail bike, which employs the Canfield Balance Formula.
Indeed, Canfield believes that there are a number excellent suspension designs available on mountain bikes today, but most make sacrifices on one end of the spectrum or the other. The same "efficient" design gives up pedaling efficiency when incorporated on a downhill bike, and will sacrifice small bump performance when applied to a cross-country bike. What's more, those characteristics can fluctuate wildly on the same bike throughout its travel. CBF attempts to minimize those sacrifices.
CBF points the chainline and drive forces directly into the instant center throughout the travel by balancing the center of curvature over the chainring, resulting in better pedaling efficiency, regardless of where you are in the travel, what terrain you are on, or what kind of power you're putting down, claims Canfield.
The red lines in this illustration represents the movement of center of curvature through travel in non-CBF designs where the instant center and center of curvature can migrate.
The red lines in this illustration represents the movement of the instant center through travel in non-CBF designs where the instant center and center of curvature can migrate.
By balancing the center of curvature on the chainline, CBF creates an instant center that can travel from a high position to low, forward to back, mirroring the rear axle and keeping the distance between the two more consistent, lessening chain-growth/pedal-kick throughout the travel. As the wheel moves up, the instant center moves down, avoiding unnecessary interruptions to the pedal stroke. The chainline pivots with the suspension around the same point, isolating drivetrain and suspension forces.
CBF is also designed to decouple suspension and braking forces, allowing the rear wheel to track terrain even under hard braking for better traction and control. "Brake jack" is virtually non-existent, says Canfield. CBF has optimal anti-rise (80%-100%) throughout travel, preventing braking forces from causing unwanted squat or rise, maintaining favorable geometry, and allowing the suspension to do its job, keeping the rider in control.
"It's not geared toward a single bike, just suspension in general," added Lance Canfield, the other half of the Canfield Brothers team. "We are simply looking to deliver a more compliant feel and not have excessive squat or lift. When you operate in finite area, you get rid of the negatives at either end of the spectrum. We have all felt those negatives in bikes over years, and we have learned a lot based on what others have done."
The formula allows the rider to set up the sag position anywhere in the travel with maximum anti-squat and pedaling efficiency. Because the chainline always points at the instant center, Canfield says, there is no way to miss the "sweet spot" in the travel. Of course, your sag and suspension setup will still affect bump compliance and how much travel you use, but if you like to run it soft or it has not been properly set up, you won't be giving up any pedaling efficiency.
Canfield believes that there are a number excellent suspension designs available on mountain bikes today, but most make sacrifices on one end of the spectrum or the other.
You will also maintain efficiency when climbing, a situation in which weight is shifted rearward, causing the bike to sit deeper into travel beyond the normal ideal sag position, and riding downhill, through obstacles and rough terrain.
While Canfield does not see the patenting of the formula as a huge financial opportunity, they are interested in licensing it.
"Sure it would help us some from a marketing standpoint, but what we really want is to see other companies building better bikes," added Lance Canfield. "We have basically spent our entire adult lives chasing this knowledge of knowing how suspension works and we feel, and our patent lawyers agreed, that we've come across a way to make bikes more efficient with better braking and less overall negatives. Now we hope to see the industry look at it and say we can make bikes better for everyone. But if not, oh well. We'll still have that Canfield feel."
For more information, visit CanfieldBrothers.com.