With its radical suspension layout and being designed by a company that took its name from a falcon, the carbon fiber Rubicon Comp from 1995 was destined to be one of the most radical bikes of its time.
Less than a decade earlier, Kestrel had offered their first carbon fiber bike, the bladder-molded monocoque 4000 road bike. And, in 1988 they shocked many with a carbon fiber hardtail for the mountain: the MX-Z, and later, a full-suspension bike dubbed the Nitro. Both of the swoopy machines looked like they were from the future, especially compared to the simple steel tubing that most riders were astride at the time. Kestrel didn't entirely forsake metal, however, as steel reinforcements were put to use inside of the head and seat tube junctions, as well as down at the bottom bracket.
Jump forward to 1995 and the Rubicon would make that once futuristic looking Nitro look downright boring. Hell, the Rubicon makes a lot of today's modern machines look yawn-worthy, but professional racer Kurt Stockton's dual-shock Mammoth Kamikaze Special took it to a whole other level. Two Shocks, 200mm of Travel... in 1995
Two decades ago, most professional downhill racers were competing aboard warmed-over cross-country rigs that saw a riser handlebar and different gearing added, and possibly a switch to different rubber if the course called for it. And that's exactly what Kestrel's Kurt Stockton had been doing, until one night when he was tinkering in his garage and noticed that part of his Rubicon's linkage appeared to be about the same length as the single Fox Alps shock that was fitted to the bike. ''It looked like the same length as the shock, so I measured it, and it worked,'' Stockton said of the experiment (one that Kestrel hadn't ever considered). I called them, and they said that they hadn't even thought about it, and the bike now had eight inches of travel with two shocks.''
The two shocks allowed Stockton to run less pressure in each, and he also says that the increased sag from doubling the travel and running a much more forgiving spring rate meant that the Rubicon's head angle was kicked out enough to help the bike's handling at speed. According to Kurt, that wasn't the only benefit: ''If four inches is good, then eight inches is great. Remember that downhill courses weren't super gnarly back then, but if you had more travel, you were less likely to flat.'' Don't forget that tubeless tires, and even burly sidewalls, were a long way off still, so just getting across the finish line was a big part of the battle.
Even in the stock configuration, with a single Fox Alps shock and a bit more than 100mm of travel, the pivoting beam design and slender swingarm looked as if it were from another planet. The beam was intended to increase leverage on the Rubicon's shock when the rider was seated, making for a more forgiving ride when a racer was in the saddle.
Being a downhill racer at the time, Stockton obviously spent less time sitting than his climbing counterparts, so the doubling of the bike's travel and its much softer spring rate meant that the Rubicon was an improvement over the stock setup when he was out of the saddle.
Not exactly the involved development story that most contemporary bikes go through, but Stockton's garage experiment story is an interesting anecdote nonetheless. You may be surprised to discover that his prototype Rubicon hasn't been the only dual-shock bike in our sport's history - Cannondale's team-only Gemini, Scott's High Octane, and a Karpiel design all employed two shocks in various layouts - but the Kestrel was by far, the wildest race bike of the last millennium. Magura hydraulic rim brakes are still considered extremely powerful today. A Bullet Bros. chain tensioner worked in unison with a custon guide to keep the chain in place.
Stockton's frame was a prototype, second shock or not, and Kestrel was experimenting with different carbon layups and designs at this point. Nothing was as certain as it is now; everything was new, and as you'd expect, there were some issues.
That long and slender swingarm that looks like it'd offer as much lateral travel as it does vertically? Yeah, it broke. Stockton recalls snapping one during a race at Vail, Colorado, in 1994, but noted that Kestrel quickly built him an updated version that proved to be sturdy enough. ''It was pretty flexy laterally,'' he said, ''but it was all new at the time, and we didn't have anything to compare it to.''
Kurt says that the bike pictured here is built up with parts from not only his time but also from when Jimmy Deaton was riding for Kestrel. A set of exotic HED wheels featured a deep carbon fiber section that was bonded to an aluminum track for the Magura hydraulic rim brakes, and the extremely tall and aerodynamic rims meant that finding tubes with long enough valve stems could be a challenge. Kurt needed to run heavy duty downhill tubes, but those only came with Schrader valves that were far too short to clear the carbon rim. The answer? Plastic valve extenders from a truck stop. When off the shelf parts won't work, you gotta make it yourself.
Another interesting item is the homemade chain guide that had to be built to work with the 63-tooth chainring that Kurt used on the Mammoth Kamikaze course. The Nylon sliders could be adjusted vertically, and the steel boomerang bolted to the Rubicon's front derailleur mount and a special adapter that was attached to the frame just above the bottom bracket. A Bullet Bros. chain tensioner was put to work to further help matters.
The brand has been owned by Advanced Sports since 2007, and while their catalog is now focused on road and triathlon bikes, the radical design of the Rubicon will be what many riders of a certain generation think of when they see the Kestrel name.Thanks to The Pro's Closet for once again allowing us access to their treasure trove of historic bikes. Photos courtesy of The Pro's Closet
Visit the feature gallery for high resolution and additional images