THROWBACK THURSDAY: 1994 DURANGO BIKE WORKS 8X8

How much suspension travel is best? Three inches? Ten inches? Should a mountain bike be able to perform in the same category as a high-performance motorcycle? Do downhill racers really need disc brakes? Can ultra-supple suspension co-exist on a machine that must be pedaled by a retired BMXer turned NORBA downhiller? The world is full of questions without answers, but few, if any, of us stay up nights pondering the unknowns. Robbie Rupe does!

We have known Robbie for years; in fact, he used to hang out with the MBA test guys and gladly pitched in during his days of making the switch from BMX to mountain bikes. So, when Robbie started up his own company, Durango Bike Works, we expected something special out of him. The result is the most outrageous custom-made downhill sled anyone has ever laid eyes on. Robbie lives in Durango, Colorado, where he founded his tiny custom frame shop to develop his ideas into rolling reality. His latest project [in 1994] was an experiment in glorious excess. His goal? The longest, tallest, heaviest, long-travel full-suspension bicycle seen to date. It was as if Robbie had found Aladdin’s magic lamp and used all three wishes to acquire the ultimate downhill machine.

Rupe explained that the 8×8 was only the first of many prototypes he would be constructing in an effort to dial in a bicycle that could be ridden as fast as a motorcycle over rough terrain. Rupe believes, and rightly so, that present downhill machines are little more than warmed-over cross-country bicycles. He didn’t limit his criticism to just the frames; Robbie also felt that the new breed of so-called downhill forks and tepid, 3-inch-travel rear-suspension configurations are baby steps on the way to maximum downhill speed. Robbie wanted to break through the incremental improvement-logic barrier and set a new downhill design standard. In typical BMX fashion, Robbie decided to kick out the jams, go to the extremes first, then back down to some realistic level.

 

TOOLS OF AN EXTREMIST

No existing bicycle suspension components (fork or shock) in the early ’90s could deliver the 8 inches of wheel travel that Rupe wanted, so he adapted fork legs from a Kawasaki KX60—a potent, downsized, 60cc motorcycle designed for young motocross racers. The Kayaba suspension forks provided 8 inches of smooth, beautifully damped wheel travel. Rupe machined his own double-plate fork crown and special headset to adapt the KX fork tubes to his TIG-welded chromoly front triangle. For a rear shock, Risse Racing built a special two-stage air/oil shock. This bizarre unit was fabricated from two Risse shock pistons, which were assembled into opposite ends of a single, extra-long alloy shock body. Rupe claims this setup allows low-speed settings to be dialed in on one end of the shock, and faster, high-speed damping and spring rates on the opposite piston (imagine the tuning possibilities). It is essentially a dual-chamber air shock with one high-pressure chamber and one low-pressure chamber. Total shaft travel of the shock is 4 inches, which translates into almost 10 inches of rear-wheel travel.

Rupe TIG-welded a massive, reinforced Easton aluminum monoshock swingarm out of rectangular tubes and thick machined plates, which pivots at the junction of the down and seat tubes above the bottom bracket. The main triangle has a radically sloping top tube, made necessary by the ultra-long fork.

For stoppers, Rupe adapted Sachs/Huret hydraulic disc brakes on both ends. The rear-wheel brake caliper required a simple bolt-on bracket, but Rupe had to machine a trick torque control arm for the front caliper to fit the fork’s leading-axle dropout. At a distance, the big suspension bike looks awkward, but closer inspection reveals a lot of thought and craftsmanship went into the giant from Durango Bike Works.

 

THE EXTREME COMPONENTS

In a break from the traditional Shimano drivetrain parts, Robbie chose a Sachs 3×7 setup. The Sachs system uses an internally geared, 3-speed/7-speed freehub combination (with a left-side disc rotor attachment to boot!), which eliminates the need for a front derailleur. The Sachs 3×7 could be a real advantage for gravity racing because the rear hub gears allow the bike to carry a wide selection of ratios and still run those fancy chainguides and idlers. Presently, downhillers must choose a single front gear and live with the limited rear cog ratios. Blowing a single turn can leave a racer bogged down in an impossible gear. Not so with the Sachs setup. Sachs uses a twist-shift with lockout switches on both sides. Lockout would be handy for dual-slalom events where a single-speed/no-error gearbox is a fact of life. Sachs’ disc brakes are reliable and well-engineered units. Sachs’ penchant for over-engineering leads to a weight problem, and Rupe’s racer was equipped with the older steel disc rotors. Aluminum-metal matrix rotors are a new Sachs option that would take a pound off the monster.

The rims are super-wide, 36-spoke Mavic 381 units, which gave the Onza Aggro/Honch 2.1-inch tires a wider-than-life footprint which are on par with the intended uses of this machine. Cranks are TIG-welded chromoly arms with black plastic chainguides bolted to each side of a single chainring. The last feature of note was Rupe’s solution to a stem. The top plate of the fork’s triple clamp was extended and slotted. A pair of handlebar clamps fit into the slots, allowing the bar to be set forward or back 2 inches, and by clamping the bar above or below the plate, the system allowed another 2 inches of height adjustment—very cool.

Big and tall shop: The high bottom bracket, way-tall fork, long wheelbase, big swingarm, hydraulic disc brakes, dual shock, and purpose-built downhill racer is two giant steps into the future. Most racers aren’t ready for the future.

EXTREME GEOMETRY

MBA measured the Rupe-mobile and found it to be well into the downhill realm with one or two exceptions: top tube length is 22.75 inches; chainstays are a normal 16.9 inches; stem extension ranged from about 50mm to 130mm; wheelbase is a whopping 43.8 inches. Bottom bracket height? Almost 14.5 inches. The head angle was a shallow 68 degrees, and the seat angle followed at 71.5 degrees. Short people need not apply for the pilot position on this mount; the center of the top tube was 33.75 inches above ground level. Rear-wheel travel measured at a new world record of 9.25 inches; front-wheel travel was 8 inches. The theoretical frame size for this pup was 18.5 inches (not considering the tall top tube). Interested in more facts? Call Durango Bike Works at (818) 610-9262.

 

EXTREME GRAVITY RIDE

Every test rider wanted to slam-dance the Durango Bike Works 8×8 (for 8 inches of front travel by 8 inches of rear travel) and after a too-lengthy verbal evaluation, the bike crew finally arrived at the most important point in the test—the riding. One of the coolest things about the western part of this country is the plethora of extended-play downhill fire roads. Our first choice was a medium-sized downhill (medium for us): 14 miles of no-uphill, fun-filled, gravity-powered yee-haw. We chamoised up (Colorado French for donning cycling apparel) and attacked the hill with some trepidation. Was the bike’s high center of gravity going to invite a high-side? Would the suspension work well out of the saddle? Were we just getting nervous before a guaranteed dose of speed?

Every test rider returned from his downhill rips with the same basic report. In the first mile two things became obvious: it was going to take a lot of velocity and a very big launch ramp to turn the Rupe-cycle into an airplane. Its super-supple suspension ate up log-sized bumps and ruts in the saddle. Only the largest bumps could tear the tires from the ground. In normal fire-road mode, standing out of the saddle was only required if the rider wanted to see further down the mountain, or to pedal hard. Pedaling this beast required real inspiration. Out of-the-saddle efforts were akin to disco-dancing on a trampoline. The bike was soft as a marshmallow, and heavy. Did we say heavy? If a low-level Navy jet hooked the Rupe-mobile, it would stop faster than an aircraft carrier. Robbie claimed the weight to be 48-ish pounds; the bike topped out the 50-pound MBA scale like a construction worker hammers a roofing tack. There were plenty of places on this bike to shave, uh, weight. The fork plates were carved brick-thick and the swingarm was a study for engine block manufacturers. Robbie said he built the bike like a tank to be on the safe side during the testing phase. A wise decision.

 

Test riders thought they were going slow at first, due to the bike’s oh-so-plush ride. We figured this might be the case ahead of time, so we brought a familiar, fully suspended, cross-country bike to accompany the Rupe-cycle down the mountain for comparison. The Rupester rolled to the front the moment things got gnarly. In really loose corners, the front end would wash out momentarily, then the rear end would slip in behind and the bike would slide around the turn. This was probably due to the minimal offset and maximum trail in the steering geometry. This was a tad disconcerting to the uninitiated, but if something went wrong, you could run off the road (within reason) and the suspension would make it a pleasant experience. Berm shots were the best way to get through a tight turn; the suspension components could absorb the hardest slam into a dirt-wall experience. Berm shots were the best way to get through a tight turn; the suspension components could absorb the hardest slam into a dirt wall, then rebound out of the corner without losing much velocity. Whenever the big bicycle did slow down, it seemed like ages before hard pedaling was of any benefit in returning the bike back to the national speed limit.

Stopping was a joy. Two Sachs discs were all this mount needed at any speed and the Onza rubber was equally capable of handling the G-forces the stoppers delivered in spades. Under braking, the Rupecycle would dive noticeably, but there was absolutely no adverse effect because the seat-crank-handlebar-wheelbase geometry was very close to the configuration developed for motorcycles. We had no fear of burying the binders into the grips when needed.

Is the Durango Bike Works (DBW) Rupe-mobile a precursor of the future? Yes. Did the Rupe-mobile answer our questions about how far mountain bike suspension can go? Mostly yes. We discovered that long-travel suspension was awesome for high-speed dirt riding, but we knew that from motorcycle experience. We were reassured that disc brakes are awesome (and required as the speeds begin to increase). The big DBW bicycle made us wish for a lower, less awkward front end, but this is only a stage one machine. The future will resolve the sizing problems or our qualms. The extreme concept design was exactly what was needed to make the future clear for Robbie Rupe’s next design, which is already in the works. If the next Rupecycle is lighter (significantly lighter), a bit more compact and a tad firmer in the suspension, Durango Bike Works will have a real winner.

 

 

Q&A WITH THE 8X8’S BUILDER, ROBBY RUPE

What happened to the 8×8?

I sold the bike, and I regretted it ever since. I only made one of them. And, I remember the time I didn’t want to sell it. But, I had a guy call me from Italy because he saw it in Mountain Bike Action. He said I want one of these things, so the guy flew over here and I sold it to him. I have no idea what happened to this guy or the bike. He’s not on Facebook or anything. He told me that he worked in a sausage factory. My friends used to joke that he really worked for Bianchi, but I don’t really know.

Why did you make it?

I was at the World Championships in Vail on a 3-inch-travel bike, and that was a lot of travel then. There were a few other guys maybe they had like maybe 4 inches of travel, but the bikes just didn’t have that much travel. I was going through this one section, it was a total G-out, probably going 45 miles an hour and the tire blew out. I saved it but almost hit a tree. You’re going to kill yourself on one of these things, I thought to myself, so I decided to make something that I’d be able to ride just as fast as a motorcycle without an engine, and that’s what I set out to do.

It was massively ahead of its time, and this was a raceable bike that I competed on at all the Nationals and World Cups. I got some top 20s in the Nationals. But back in those days, a lot of courses had hills in them, and that bike was 50 pounds. That bike and hills—forget it. As far as how it rode? It was just so far superior to any other bike. It’s a weak point with the tires, because I could go so fast in some sections. I flatted at quite a lot of the races, just because I was going so fast. I had the fastest time in (Mount Snow) Vermont going through the speed trap. Looking at it now, if I kicked the head angle a little bit more out, I could race it today with some modern rubber. The thing was indestructible.

I just won’t say any names, but there were more than a couple of the magazine editors that would not ride the bike. When people looked at this bike, they literally lost their minds and didn’t even know what they were looking at. They wouldn’t even ride it in the parking lot. They would say, “Nah, nah, it’s just too much,” and take a picture of it and move on.

Did any other racers ride it?

Plenty of people rode it. Johnny [Tomac] rode it and thought it was great. Myles Rockwell loved it. He couldn’t believe it when he got on it. He was on Cannondale, and it was a little bit ahead of his time, but this bike was completely different. I let Gerhard Zadrobilek try it. He took it down some stairs. He was just like, “You gotta be kidding me, this is gonna change everything.”

Why didn’t you make another one?

I’m not a CNC guy. I just have manual machines, and that’s such a tremendous amount of work and time. I made other downhill bikes, some lighter versions that were 5-inch to 6-inch travel. But, nothing that was quite like that. We’re still making custom bikes. I don’t do really any downhill bikes too much anymore, mostly road bikes and hardtails. But, I think I am going to reinvent this bike. It will be along the same lines, but, basically, a downhill bike that you can ride everywhere.