Every mountain bike designer should have a picture of the Mountain Cycle San Andreas hanging somewhere in the office. Road bike DNA has polluted the development of the mountain bike since its inception. The spindly double-diamond frame that has been hardwired into our minds was the pinnacle of efficiency when bicycles were soldered together from sticks of steel and admittedly, if you're into hardtails, or still soldering sticks together, it's a tough design to beat.
Most of us, however, ride dual-suspension bikes, and in spite of the challenges that funky linkages, shocks, high stack heights and wide pivots have imposed upon the stodgy double-diamond frame, the bicycle industry seems to be blind to any
Mountain Cycle Founder Robert Reisinger. RC photo
alternative. The San Andreas stands as one of the few exceptions. It was launched in 1991, and to this day its elegantly simple design reminds us that we could have done better.
Robert Reisinger founded Mountain Cycle in San Luis Obispo, where he earned a degree in mechanical engineering at the polytechnical university there. Before that, Reisinger had one foot in aviation as a commercial fixed wing and helicopter pilot, and another in motocross, where he did a four-year stint as a pro racer and test rider for Kawasaki. Oh, and he shares a world record for building the first human-powered helicopter capable of sustained flight. That kind of diversity helps explain why Reisinger's first opus as a mountain bike maker was such a radical departure from all that cycling held near and dear. Before he could build the first San Andreas, however, Reisiger had to design and manufacture two of its key components.The First San Andreas
"I started Mountain Cycle right after I graduated," says Robert. "I had a good idea of what I wanted, but before I got started, I went to bike shows, checked out prototypes, and asked questions. Brent Trimble's carbon X-bike, the Kestral Nitro and the Mantis Flying V were very influential."
Reisinger was sure of one thing: dual-suspension was the future of the mountain bike. And, as if that decision wasn't contentious enough in 1989, he planned to equip his new bikes with hydraulic disc brakes. Near the end of that year, Reisinger had sketched out the San Andreas frame. It was an elegantly simple design. A large diameter monocoque aluminum structure carried the loads between the highly stressed bottom bracket and head tube. Its single-pivot swingarm was also a beefy box section, welded from hydro-formed aluminum sheet. The voluminous width of the front section made the swingarm pivot very stiff, and their close proximity required no linkage to drive the shock. To support the rider, Robert borrowed from racing motorcycles and devised a bolt-on seat mast that straddled the shock.
To understand how revolutionary Reisinger's concept was, if you overlaid a drawing of a conventional double-diamond frame on top of the San Andreas, you could erase its top tube, down tube, seat stays, chain stays and half of its seat tube. His design literally filled the empty space inside of the classic mountain bike frame.
In one fell swoop, the first-time bike designer solved every major issue that would plague dual suspension mountain bikes for decades to come: It was inherently stronger and stiffer, had plenty of stand-over clearance, room for short stays and big tires, it offered modular frame sizing, and its suspension kinematics were completely unhindered by frame constraints.
Reisinger, however, had to jump three hurdles before his dream bike could become reality. Back then, viable suspension forks, shocks, and disc brakes weren't hard to find - they didn't exist.
With only $5000 USD to launch his company, the young product engineer had to make some hard
choices. Robert shelved his frame design and went to work on a suspension fork, which in turn led him to invent his own disc brake system. Before he was a bike maker, Reisinger was manufacturing and selling his inverted "Suspenders" fork and "Pro-Stop" cable-actuated/hydraulic disc brake.
"I designed the fork and co-developed the brakes at the same time," says Reisinger. "I had just come out of testing with Kawasaki. The inverted fork was in its infancy at that time. I remember putting a Fox inverted fork on my bike - it turned in perfectly without the wobble that the flexing stanchion tubes caused. It was like a different bike. An inverted fork made perfect sense. The uppers were so structurally stronger with their larger diameters."
But, cycling tradition dictated slotted dropouts and quick release axles, which created too much flex. Reisinger said that clamp-type dropouts with a through-axle would have handily solved the problem, but that would have scared people off. After three design failures attempting to integrate the universal 8-millimeter-axle quick release front hub standard, he arrived at a compromise.
"I settled on a 12-millimeter front axle with its own locking system," he said. "To get enough stiffness, it had to be a physical, twist-on axle, and I designed thick dropouts with border lips that captured the axle so it couldn't go anywhere if it wasn't properly tightened. Today, we use through axles, and that makes it easy."
Considering his motocross background, it would be easy to criticize Reisinger for opting for a simple elastomer stack for his suspension fork. Pro motocross racing may have been enjoying a renaissance of suspension technology in the early '90s, but by comparison, mountain bikers were still knapping flint.
"Elastomers? I had just come from MX testing and suspension development," explained Robert. "All those adjustments and technology were just too much for cyclists at the time. I distilled it down to a color-coded elastomer system that was easier for the consumer to understand. It made the suspension much more reliable and easier to work on. Also, I had to sell my bikes for a price that people could afford."Pro-Stop Brakes
Inverted forks require some sort of hub brake. Reisinger's Pro-Stop disc brake was a compromise between the full-hydraulic system that he wanted to make and the reality that few riders would be willing to forego Shimano's cutting-edge index shifting in order to experiment with disc brakes. He designed a hydraulic caliper that incorporated a small, cable-driven master cylinder - a concept that was also used successfully by AMP designer Horst Leitner for the same reasons.
The first rotors simply threaded onto specially made Bullseye hubs. Shortly after, however, Reisinger developed a splined interface that was fixed by a threaded lock ring - the predecessor to Shimano's present Centerlock mounting system. Those hubs were made by Pulstar and were standard on most San Andreas models, including the bike featured here.
The most difficult part of the Pro-Stop's development was getting the proper brake pad compound. Reisinger opted for hard anodized aluminum rotors to save weight, but could not find a pad maker that would cooperate to develop a matching compound. Eventually, he was directed to Andy Brinzey in North Carolina. Brinzey made custom brake pads and components for NASCAR race teams. It took six months, and a few molds to dial in the right material. He made all of the Pro-Stop pads from then on.
Pro-Stop brakes were a little noisy at times, The aluminum rotors were designed to shift laterally about one millimeter on a six-bolt spider. They would self-center most of the time, and when they did rub on the pads, the noise was the only detriment, as the pad material created insignificant drag when there was no squeeze force upon it. Compared to rim brakes, however, they were light years ahead. Mountain Cycle sold a lot of them until Shimano and Hayes settled upon a universal hub interface and the brake market was swept up by OEM suppliers.
Made in the USA
Robert's post-graduate hubris came to a screeching halt when he started shopping around for a supplier who could form the matching halves of his monocoque frame and swingarm. Most of the fabrication shops who could form the parts were churning out components for aerospace or military contracts. The tooling quotes alone were astronomical. "I was arrogant," says Robert. "I didn't know that an aluminum monocoque couldn't be done."
Almost by accident, however, Reisinger stumbled upon a man in San Francisco who was forming complex shapes from aluminum sheets using a hydraulic press and rubber blocks. He called the process "hydro-forming."
"My dad and brother helped me make a huge press and I figured it all out," said Robert. "I made my first patterns out of wood. We did the sheet metal in my shop, but all of the CNC-machined small parts were done outside. The first 100 frames were welded by a contractor, but after those, we brought all the welding in house. The first ones took three hours to weld. Then I ended up with a couple of guys, one from Piper and another from Lockheed, who were so good. Towards the end, they could weld a frame in 45 minutes. They knew all the tricks."
Mountain Cycle purchased a CNC machine, followed by a heat treating oven and, with the exception of powdercoat painting, every operation was eventually brought in house. By the mid-1990s Mountain Cycle employed 30 workers. The San Andreas had jumped from two and a half inches of travel to five, and was earning a reputation as a pioneering all-mountain bike. The product line expanded to include a downhill version of the San Andreas, and two more conventional XC designs; the Moho softail and CSX suspension bikes. Road bikes were in the works. From the outside looking in, everything was great, but industry price wars and an economic downturn were looming ahead.Size medium. Geometry was adjustable on later models
"I was fighting to keep the doors open," says Reisinger. "I had a nice run around '93 when suspension was going off. At some point I had 30 people and a manufacturing business. The market was reaching out for full suspension. But I had 300 frames in inventory and was totally in debt. I had to shrink down to only six people."
That should have spelled the end for Mountain Cycle, but just when all looked black, orders again poured in. They sold all of their inventory and suddenly were back in business. Reportedly, they exceeded a million dollars in sales annually before the mountain bike market dropped off in '99.
"By '99 the market was getting soft," Reisinger admitted. "I had stopped making forks, because there were many options available. Costs were going way up, but the elite level bike buyer had not arrived yet. It seemed like I was always a little too far ahead of the curve - with suspension forks, disc brakes and then high-end bikes. By the end of the '90s, I was exhausted with the struggle to keep it all going."
Eventually, Reisinger sold Mountain Cycle to Kinesis Bikes - a contract bicycle maker with factories in the US and Asia that was searching for an elite level house brand to expand into the market with. The effort peaked around 2004 with nine models in the range, but did not bear much fruit.
"I was a good young engineer with skills to make a good product," Reisinger said. "But the business aspect was the part I had to learn. Who would have known that a few years later, bicycles would be selling for ten thousand dollars? I missed that one."
Reisinger returned to the motorcycle industry, founding a high-performance exhaust business. His latest endeavor is designing protection gear for 6D Helmets. He races motocross again, and in our small universe his San Andreas will probably be remembered as one of the most influential mountain bike designs of all time.