Rocker Carbon Gen 3

To quantify what made our favorite metal models ride the way they did, we pulled a selection out of retirement and put them back on our test fixtures.

We recorded how the frames responded to loads in different directions: lateral, torsional, vertical compliance, pedaling stiffness, twist and splay. Where did they move, and how much? Where did they resist movement? We started putting numbers to “feel.”

There's a reason people love good steel and Ti hardtails. Metal has a willingness to move underneath you. Hit something hard and the frame gives a little. Load it through rough terrain and it can twist and splay rather than reflecting every input straight back into the rider. That movement can help the tires follow uneven ground, soften repeated impacts and give the bike its forgiving character.

But not every movement is useful. Stand up to put down power and metal bikes can feel vague and rubbery. Load too hard in a corner and a metal bike can bend and twang unpredictably, rebounding like an undamped spring. You can manipulate tube diameters, wall thicknesses, butting and shapes to control those behaviors, but because steel and Ti naturally ride relatively soft, the challenge becomes making them stiff enough without building a boat anchor. You start hitting the limits of the materials themselves.

With carbon, we have infinitely more control. It's light, it's excellent at damping vibration and flex rebound, and with nearly unlimited combinations of layering and shaping, we can manipulate every millimeter of the frame to bring out the behaviors we’re looking for. Want the bottom bracket to sway 10mm instead of 14mm at a given load without affecting vertical compliance? This can’t be predictably done or consistently replicated using other materials.

Because of this, we can have our cake and eat it, too. The Rocker combines the response, precision, low weight and vibration damping of carbon, with the forgiveness, traction and natural movement we loved about our best metal hardtails.

We made the downtube smaller in diameter, and the toptube slimmer and lower. Together they give the front triangle more freedom to twist and splay, allowing the bike to move naturally beneath the rider.

Out back, a scalloped chainstay shape adds vertical compliance while maintaining lateral support. The seatstays get thinner as they approach the frame, and a kinked shape near the seat tube gives them room to flex vertically. They meet the frame farther outboard at the seat tube/toptube junction, giving us another way to tune how the rear triangle responds to load.

Where we didn't want movement, we went the other direction. We added material specifically to the non-drive chainstay to increase pedaling stiffness.

That's the advantage of working with carbon at this level. Fiber orientation, layup, wall thickness, tube shape and cross section all become tools. Instead of deciding whether the frame should be stiff or compliant, we can ask where, in which direction, and how much.

Lay power down and you still get the crisp response that makes light carbon hardtails addictive. Hit rough ground and the frame has more freedom to work underneath you, helping the tires stay connected rather than skipping across the top. There's more grip when traction gets scarce, less chatter when the trail gets spicy, and less punishment over the long haul.

Make no mistake, though. The Rocker is still unmistakably a hardtail, with all the efficiency, response and tactile ground feel you’d expect. It just has a lot less chatter. And a lot more soul.

Getting the frame to move the way we wanted also gave us an opportunity to rethink the way we approach belt retention.

We've spent years innovating and patenting belt-drive mountain bike technology, and traditionally, frame stiffness has been an important part of creating a secure system. The less the rear triangle moves, the more consistently the belt and rear sprocket stay aligned. Using larger sprockets can help as well, by reducing the forces acting on the drivetrain.

The trouble with both is that they come along with some undesirable side effects. A rear end that’s stiff enough for the drivetrain is overly harsh to ride. Large chainrings hang down lower and get bashed up more easily.

So rather than design around the problem, we addressed it directly. Say hello to The Spotter.

The Spotter is a small guide positioned below the belt at the rear sprocket. During normal riding it sits just clear of the belt. If the belt begins to climb away from the sprocket under a particularly hard load, the Spotter physically limits how far it can go to keep it engaged.

It’s a simple idea that decouples a design constraint we’ve been battling for years. Rather than relying on the stiffness of an entire carbon rear triangle to provide another layer of belt security, we can handle that job right where it matters.

The Spotter suddenly gave us freedom to achieve the flex and compliance goals we were after. We could tune twist and splay into the chassis without asking those characteristics to coexist with a belt-retention strategy based largely on resisting movement.

The frame is allowed to tango, while the Spotter stands guard.

Conceptually, it’s much like upper chain guides on modern geared mountain bikes. Narrow-wide chainrings and clutched derailleurs already provide excellent chain retention, so chain guides spend nearly all their time doing nothing. Some riders charge hard enough to appreciate the added security. Others take them off and never drop chains. Same idea here. Like a chain guide, the Spotter doesn’t contact the belt unless it needs to; it just sits close enough to stop a derailment.

Knowing it’s there also allows us to run smaller sprockets to maximize ground clearance. By moving from a 46 x 28 combination to a more compact 42 x 26, we gain about 7mm while keeping the overall ratio nearly identical.

For extra insurance, we also added ISCG tabs, giving riders the option to add a bash guard.

Better belt security, more ground clearance, and a ride that feels brand new and comfortably familiar at the same time. Welcome to the party, Spot Spotter.

It’s what makes the Rocker the most versatile carbon hardtail on the market, and we’ve made significant improvements here as well. A new dropout design brings the full range of chainstay adjustment to geared builds. The new geared drive-side dropout uses the now-ubiquitous UDH interface to mount a conventional derailleur, or accepts a SRAM Full Mount drivetrain directly. Either way, you get the full 15mm of rear-center adjustment, from 426 to 441mm.

Slam it forward for quick, playful responsiveness, run it all the way back for more high-speed stability, or find your happy place somewhere in between. Larger lateral clamping screws create a more robust connection, and both dropouts now use a fully locking tensioning system to hold the axle securely once you've put it where you want it. And like all Spot dropouts, wheel changes won't affect chainstay adjustment, brake alignment or belt tension.

The new frame gave us a chance to revisit geometry as well. Compared to the outgoing model, the new Rocker gets longer, lower and slacker — all the right words.

In the overlay above, the new Rocker is in yellow and the previous Rocker is in red.

With a 120mm fork, the head angle moves to 66.4 degrees and bottom bracket drop increases to 62mm. Reach grows 5mm across all four sizes. They're not massive changes individually, but together they give the new Rocker more room and composure without dulling the quick, responsive handling that makes hardtails fun in the first place.

Minimum chainstay length is 12mm shorter than the previous Rocker, while still leaving plenty of adjustment to suit terrain and riding style.

We also lowered and sloped the toptube, particularly on the larger sizes, creating more room to move the bike around underneath you when the trail gets technical. We think it’s considerably more useful than using that space to hit your knees on a piece of carbon.

We have a proven history of innovation and an unwavering commitment to top-level engineering and design. From our groundbreaking Living Link suspension technology to our CenterTrack belt system invention, Spot Brand creates bikes that go faster, last longer, maximize your enjoyment, and simplify your cycling lifestyle.

The Lumpkin family founded Avid in 1991 and grew the component company into America’s largest brake manufacturer. After selling Avid and acquiring Spot, we turned our attention to building better bikes. First, we revolutionized the reliability and simplicity of belt drives by creating the CenterTrack design that has made Gates Carbon Drive the world’s best-selling and most durable bicycle belt system on the market.