Revel bikes launched earlier this year with one goal in mind, build the absolute best full-suspension mountain bikes on the planet. To do so, they collaborated with Chris Canfield and licensed the CBF suspension platform for use on the Revel Rail and Revel Rascal. Adam Miller of Revel Bikes was looking for the best suspension platform with the least amount of compromise. After demoing a Canfield bike a few years back, Adam found what he was looking for.
The CBF formula focuses on the Center of Curvature instead of other aspects of the rear suspension. This allows the designers to achieve extremely precise kinematics to boost performance in pedaling, braking and overall plushness. No matter where you are in the travel, the Center of Curvature is optimized to be right above the chainring.
A few months ago, Jeff and Adam of Worldwide Cyclery took a trip to Colorado to visit the Revel Bikes headquarters and find out for themselves. While there, they had the chance to hit the trails with Adam of Revel and talked with lead engineer Jeremiah Starkey to find out in person, what makes CBF so special. They also sat down with the man himself, Chris Canfield, to discuss CBF development, licensing, and more. This is a long one so be sure to grab a beer, sit back, and relax.
Watch our review on the Revel Rascal:
Last August, Adam and I took a little trip to Colorado and we got a lot of cool mountain bike stuff done. We spent the first day at the Yeti Cycles headquarters, then we went to the Revel Bikes headquarters in Carbondale, Colorado, and finally we went to the SRAM Colorado location in Colorado Springs.
While we were out at the Revel headquarters, we got a lot of bike nerdy stuff done. We got to spend time with Adam Miller and Jeremiah Starkey, the two co-owners of Revel Bikes. We also got to hang out with Chris Canfield, who is one of the brilliant engineers behind the design. One of the Canfield brothers himself! We got to go out there, ride the bikes on the trail, talk to the engineers about these things and really kind of dive into the super nerdy details of what CBF and the Canfield balanced formula is.
If you didn’t know, Revel is a newer brand. They launched just March of this year and they came in swinging with absolutely phenomenal bikes that kind of just go par for par with the best super bikes out there. I’ve said that line before, but it’s true -- I really like these things! It’s been killer to have them in our stores. This is my personal bike that I’ve been riding (and did a little dream build on). I absolutely love being on it.
So check out some footage -- this is us out there talking to these guys and really just diving deep into the super nerdy stuff all about the suspension platform and what really makes it unique. Because when a new brand shows up, a lot of times they kind of have this off-the-shelf 4-bar -- typical almost. I won’t say “generic,” but pretty basic suspension platform. Revel doesn’t. They have something unique that’s patented; that’s CBF and that’s what we dive into with those guys. Check it out! (Music)
We are now out on the trail with the co-owners of Revel Bikes, Adam and Jeremiah, and we’re gonna see how these things actually work on the trail. You’ll get some good slow-mo footage of the suspension in action! (Music)
So we just rode up a nice technical section with some good rock ledges. These things definitely climb amazing -- it’s incredible how it doesn’t want to get hung up, how it pushes you forward. Talk to me in the engineering sense, like how does that anti-squat work, and how does that give you the engineer terms?
So the biggest thing with the CBF suspension platform is that the chain is always perpendicular to the axle travel, so there’s no energy wasted pulling up or down. It all translates into turning the wheel around so that you feel that there’s no wasted movement in the bike as you climb, and then with the balanced out anti-squat it keeps the suspension active. Yet it still pedals really efficiently.
Yeah, it makes sense for 165 travel 27.5 bike, things just motors, you get in those sketchy spots when you feel like you’re gonna tip, and you’re awkward and off-balance -- it just keeps going! Its awesome super-impressive stuff.
Thanks for that, it’s definitely been a long time in the making. But we’re pretty impressed with the bike, and that kind of tip point is where on most bikes you’re used to not being able to transfer the power in there, or having a really large anti-squat or something that gives you that tippy feeling. This when you power down, it just still goes to track during the around, turning it and so it’s bouncing up and down and you’re just going forward.
Killer. So you were mentioning to a lot of other suspension platforms out there, they kind of baked a lot of anti-squat in there, so maybe on the road or on a really smooth, flat surface it feels like it pedals super efficiently -- but when you get in those technical sections like we just did, that’s where it can kind of get hindered. Whereas this will kind of work consistently across both those scenarios.
Right, with high anti-squat numbers you get, you get the kind of stiff, almost locked-out feel of the shock when you pedal. This works great if you’re riding on the road or something smooth, but then as soon as you hit a bump where the suspension needs to move, it doesn’t work so well. So this bike balances all that out so you get a suspension that actually still moves and propels you forward.
Yeah, killer! Well let’s try it on some more stuff -- yeah, sounds good! (Music)
So we just rode a ton of uphill, a ton of downhill, a bunch of gnarly chunks, some epic riding out here in Carbondale. I think my biggest takeaway on these bikes is the overall consistency of the performance -- uphill and downhill -- technical climbing kicks ass flat. High speed just pedaling is awesome, and downhill just chunk is killer! So we already talked about climbing: what makes these things shine on downhill?
Well, downhill I think you really break it down into three key characteristics: the anti-rise which we’ve talked about a little bit, lets you keep traction while you’re braking, which is super important. The leverage ratio is another thing that’s got to be pretty fine-tuned. It’s hard to dial in, but we feel like we did it with these bikes. And then the axle path on the back. So those three things are what leads you to good downhill performance and trying to tune each one of those is a delicate balance. We feel like we’ve done pretty well on this bike?
Yeah, because one of the harder things about full suspension mountain bike engineering is just making it work well when you’re on the brakes and chunk, making it work well when you’re just off the brakes, kind of flowing, and then still having it not suck when you’re climbing. So that’s like balancing all those main things.
Balancing the uphill with the downhill, even the different aspects of the downhill is challenging. And that’s one thing that we feel like we’ve really done well with this bike. There’s lots of competition bikes out there that do one aspect well -- or maybe two aspects well, but we feel like this bike is the one that you actually get all the aspects and they’re really well-balanced.
Killer man, I agree. I think they ride well. You guys crushed it man, you guys did a good job.
Oh cool -- let’s go ride some more bikes! (Music)
If that wasn’t enough for you, we have more! So now the next thing that’s coming up, we’re back at Revel’s headquarters and I ping Jeremiah with even more questions. And then I hit Chris Canfield with a whole bunch of questions, and he dives more deeply into the details of how this stuff works: how he developed it with his brother over time, and there’s even more bike nerd stuff in it, so check it out!
Chris: We’ve been working on CBF since 2008 and then started producing our first CBF model in 2015 when our patent got issued, and we’ve ran it on the balance 27.5 all mountain bike and then the riot of 140 29er, and in 2016 Adam found us at Interbike through a few colleagues of ours, and got to ride the bike. He was shopping for a suspension design and he was like just a couple hundred yards and he comes back and he’s like, ‘Would you licenses for us like NOW. Love to have the marketing to spread this, and we’re not gonna build everyone’s version of a CBF -- that’s what they want, you know. We weren’t doing carbon at the time, so we started working with him in 2016 to set up his bikes. So since then we’ve done his Rail, the Rascal, and a new one that I can’t talk about. (Music)
Nobody really sees the behind-the-scenes stuff, but we started in1999 and there wasn’t linkage -- there wasn’t information about what these things do. We were guessing in the dark, shooting off the hip on our first few models like the big fat fatty fat and the fatty fat and until this, the suspension program came out that just dissected stuff, and then that just turned me loose. I got my little ADD/can’t-sleep/brain- going-nuts going on. Sweet, now I have like a suspension program to analyze everything that’s supposed to be happening in this computer model. And then what’s happening in real life, and what I’m feeling versus what the computer says, and then what my models are doing versus what the other bikes are doing. And then I was able to get on anybody else’s bike so they’d let me ride and feel their bike, and then go, ‘Okay what’s it doing in the program?’ So I became obsessed with just dissecting all this stuff and learning as much as I could and so I’d just be playing around like modeling stuff a ton. And then it was 2007. We had made our first, we called it the one-suspension and we made four different models with one suspension. It had a really long upper link and a really long lower link and it pedaled really well. We were like, this is great, this is super good! And a company Versus cycles in 2008 was going to do a parallel link bike, and he rode our bike at Sea Otter and was like I was gonna try to develop one but I can’t do it better than this. Can I just license this from you guys and then I can just build it and run it, and I don’t have to do a bunch of mucking around trying to figure out how to make these things work because parallel link bikes -- little short little link, guys -- they can drastically be horrible. If you do them wrong, they inchworm, or they bob way worse than anything you’ve ever been on. But if you do them right, they do magical stuff and so that was the first time that we thought, okay this is great. This guy’s gonna license from us. We had a big deal going. And then the 2008 market crashes and they go out of business next year, so during that time I’m setting up a suspension forum and the current one suspension had, let me pull it up. It had a center of curvature that was kind of small and isolated, and a small amount of movement and I saw that the axle path parameter lines in the linkage program were kind of gathering in a single spot, and I thought, ``What if I put that little single spot on top of the chain ring instead of down here, on the back of the area behind the bottom bracket? What if I lift it up and put it on top of the chain ring? That shouldn’t be all that hard, and then it would kind of balance on top of it.
I started modeling and it was like, WHOA, wait a sec! If I just isolated up here and then the instant centers are gonna be right in front of it, the little balance, the happy point, I could track that instant center all the way through because the chain is your drive line, your force line for all this stuff to work. And it’s rotating there, and if I rotate my center of curvature spots right there, it’ll rotate in the same spot. And if we condense these things tight enough we can track those things all the way through travel. And guess what? That was patentable. So I was like, oh we can snag this so we have a whole oval area on top of the chain ring that is protected, that is the CBF range. And so it was sometime in 2008 that it all came together. And then it took us until about 2013 before we applied (for the patent); you know it takes money, it takes partners who say, ‘yeah let’s do it, let’s spend the money and do it!’
And then in 2015 it came out and we had tested it, and it was just like having that on there moving the same spot as the chain moves. It’s also like when you climb and chunky stuff, the chain and the suspension are moving in the same spot and it doesn’t kick your feet around, it doesn’t have weird interactions, and it’s able to move without any power transfer loss. So even though you might be seeing movement in your CBF bike, body bounce is moving it, bumps removing it, but you don’t feel any energy loss, you don’t feel any momentum spin your back tire loss because there’s nothing -- it just wants to transfer power to the wheel because it’s always perfectly balanced into that perfect instance center as it tracks around. And so like a Canfield is isolated right on top of the chain ring in a little tight spot, with Revel’s bike he was saying, ‘I gotta get a water bottle, you got to give me a water bottle in there. Dude don’t even bother with this crap I can’t get a water bottle. So we had to open up our upper link on him, move it up and back for him. That basically meant that that tight spot wasn’t able to be maintained. So I got it to where the center of curvature kind of rotates across the top of the chain ring and a gap about this big, and that movement actually feels really good. Your body bounce comes across the top of the chain as you’re moving forward, with that weight it kind of follows it a little bit and resists that body bounce a little bit more than sitting as static in that one spot. And it felt so good.
Jeremiah: At Revel -- I’m the chief operations officer -- and I do all the engineering because we’re a small crew. So I’ve got to multi-task.
I started working at RockShox in 1998 and while I was there one of the works that we were working on was the Bluto fat bike fork, and that’s how I met Adam and the rest of these guys when they were at Borealis and then since then we always stayed in contact. And we thought at some point it would be pretty awesome for us to get together and do something. (Music)
Adam told me that he rode it around 2015; I think he was at Interbike in Tahoe. And he was like, ‘Man, we should definitely license it,’ And I had never ridden a Canfield anything with CBF at that point, but I knew a bunch of people that I trusted that are pretty good riders. They knew what was going on and they all liked it, so well, it seems like a good idea! So we got some rides on it and started working on laying up the suspension design for what we were gonna do with Revel Bikes. Chris Canfield came up with kinematics of it fell into the CBF platform and we went back and forth, you know, minor tweaks and stuff, to get exactly what we wanted. There was a bunch of prototyping and behind-the-scenes work to finally get something that we were pretty happy with. Yeah, that was the rail. So we got that kicked off and released, which is pretty sweet. (Music)
I think the CBF is mostly focused around pedaling, which is where you’ve noticed the things you’re gonna notice on the trail is coming with pedaling. Most of the other designs that are on the market you can kind of band-aid certain things to make it seem okay on the trail, but you can’t really get the pedaling characteristics that you can with the CBF. Pedaling through rocky terrain where your suspension needs to be active -- but not wallowing, mushy or inefficient -- that’s the biggest thing I think you notice with the CBF.
Other particulars with our bike that I think are not necessarily related to CBF, but the anti-rise and the anti-squat that we’ve zeroed in on using the CBF design. The layout is better than anything else that I’ve ridden out on the market right now.
Essentially they’re kind of opposites of each other, like wheel torque in one direction or the other and anti-squat kind of makes the bike pedal efficiently where it’s not pulling up or pulling down. It’s kind of balancing it out in the CBF. With the CBF layout you can kind of get that across the whole range of travel, rather than just SAG. This is what most other brands are striving for, to really nail it at the SAG point. With the CBF you get the positive pedaling characteristics throughout the whole thing, so if you’re climbing up a really steep trail and you’re hitting a bunch of rocks, you’re obviously not sitting at the SAG point very much, you’re bouncing around with your weight shifting and you really notice that you feel like every turn of the cranks really makes you want to go forward with a CBF design. And then from the braking point on it’s the anti-rise. The best way to describe it is you would feel like it’s a neutral point -- like you’re trying to get to what the rider feels as neutral. So when you’re coming down a really mellow grade with washboards or small ripple bumps, when you hit the brake it doesn’t affect it too much. You don’t lose traction and start to skid. Or when you’re pointed down really steep chunky rocky stuff where you are almost on the brakes, the whole time that the suspension still moves and you keep traction. So dialing that in is definitely one of the highlights of our bikes.
An anti-squat is the chain pull forces against the suspension and the anti-rise is the braking forces against the suspension and so they’re kind of opposite, but you always want the forces to be in balance. What you’ll notice is that when you pedal the bike goes forward -- it doesn’t go up, it doesn’t go down, it goes forward. That would be the anti-squat. And then in the anti-rise it’s kind of the same thing. When you hit the rear brake it doesn’t pitch you over the bars and it doesn’t squat down in the travel and the suspension gets stiff and you lose traction. Braking really comes down to the traction and then the feeling like you’re not being shoved one way or another. (Music)
Leverage ratio wheel path. Those are the kinds of things the leverage ratio and the wheel path, you can kind of set those up with any design like you can get to that and one thing that is gonna be unique to our bikes is what we think leverage ratio and wheel path should be. And that definitely plays into that feeling of straight-line rocky smashing through stuff or hitting jumps or even just the ripple bumps, the washboard type small hits. That all comes back to ratio leverage.
Leverage Ratio is best described as the mechanical advantage of the travel and the axle, versus the travel in the shock. So this might move six inches, and this only moves two-and-a-half inches, and so changing the rate at which the wheel moves to what the shock moves is what defines the ride characteristics that you’re looking for. And it’s pretty fine-tuned; it’s like a progressive rate of 0.6 to a progressive rate of 1.2 is a massive difference. It’s not even like it’s the same bike, even though it might look identical. (Music)
Our bikes have a slightly rearward axle path through the first half of a travel, and then back to forward axle path in the second half of that travel. That keeps the distances from getting too large or changing too fast, and then the rearward axle path helps you absorb those square edge hits and lets the wheel actually get out of the way. Generally when people have a bike that they just described as hanging up like you kind of know you’re going down, you’re smashing through some square-edged hits and you kind of feel like you’re dropping anchor each time -- that’s usually because the wheels got to go forward, and so when the axle has to move forward the wheel has to accelerate. Because it’s got to go faster, it’s got to travel that distance faster. So the wheel is accelerating so you have all this inertia that basically fights your suspension. And that’s what people feel as a hang-up.
I think the number one defining characteristic is that it’s a versatile enough design that you can tune it to where you want and the biggest thing you’re gonna notice is the pedaling efficiency. And it’s a design you could make into a cross-country type bike if you wanted, or a very downhill-specific type suspension. But with the other designs that are out there, you’re kind of focusing in on one part of the travel, wherewith the CBF you can get those characteristics through the full range of travel. Yeah, this CBF platform as a holistic approach has a lot less compromises than the other designs that are available out there right now -- both climbing and descending.
Jeff: If you are still around and watched all of that, thank you very much. That is a lot of very deep and rich bike nerd info and engineering stuff. Hope you liked it! Again, Revel has been doing some absolutely amazing things, and these bikes ride as good as we talked about and theorized and discussed in this whole video -- and some of our other videos about Revel. So thanks again for watching. Hit that subscribe button, don’t hesitate to ever reach out to us about Revel Bikes. (And if you want to ride one, come by one of our locations!)