Ibis's BowTi debuted in 1997.

THE SHORT, TURBULENT LIFE

OF URT SUSPENSION

Hindsight is always 20/20

Dual-suspension

"Sweet Spot" Suspension is Born



Castellano insisted that suspension bobbing and mushy pedaling were never going to be eliminated as long as the swingarm hinged near the frame's bottom bracket, so he devised a simple fix.



Castellano moved the bottom bracket off of the frame's front triangle and onto the swingarm. His logic was that the rear suspension would be free to soak up bumps while the rider was seated, but when standing or pedaling in earnest, a percentage of the rider's weight would shift to the swingarm and cause the bike to pedal more like it had a rigid rear end.

Drawing from John Castellano's "long-travel rear suspension" patent, issued December 12, 1995.

Graphic in the 1994 Ibis Szazbo catalog explains the importance of Castellano's Sweet Spot pivot location.

Castellano unveiled his creation sometime around 1994, and it received a warm welcome. Scot Nicol of Ibis Cycle fame was first to embrace the Sweet Spot, with the 1995 debut of the Szazbo, and followed by the pivotless titanium BowTi, which would become one of the most collectible vintage suspension bikes of all time.



Other notable brands followed quickly on the heels of Ibis and the ensuing wave of favorable press, who dubbed the concept, "Unified Rear Triangle" suspension. At the height of Castellano's URT revolution, he had licensed his Sweet Spot design to Ibis, Mountain bike pioneer Joe Breeze, WTB, Schwinn, and Rocky Mountain.

Reportedly, mountain bike pioneer Steve Potts built Castellano's prototype BowTi pivotless URT frame. - John Castellano photo

Schwinn's Homegrown was an aluminum Sweet Spot design, made in the USA. - Bonustomato.com image

URT Goes Big Time

Trek's Y33 combined its new OCLV carbon process with an aluminum URT rear suspension of their own design. - sycheah56 photo

It was eye candy and a URT. Mountain bikers bought them by the thousands.

Trek's URT design fell short of that goal. Its swingarm was significantly different than Castellano's Sweet Spot system, with very little rearward offset at the bottom bracket and a pivot location that was much lower in the chassis. Its pedaling felt much more like a conventional rear suspension bike, but those details did not seem to matter. It was eye candy and a URT. Mountain bikers bought them by the thousands.

Trek's URT design fell short of that goal. Its swingarm was significantly different than Castellano's Sweet Spot system, with very little rearward offset at the bottom bracket and a pivot location that was much lower in the chassis. Its pedaling felt much more like a conventional rear suspension bike, but those details did not seem to matter. It was eye candya URT. Mountain bikers bought them by the thousands. Trek's take on the URT put the swingarm pivot lower, with less bottom bracket set-back. - sycheah56 photo

Klein Mantra Pro

The Mantra was the least understood bike that we made at Klein. They had almost five inches of travel at the wheels and that was a lot for the time. Most people didn't believe that we made it to race cross country and endurance events. — Darrell Voss

Dark Days Ahead

Slingshot was technically the first URT suspended mountain bike. Its head tube angle was 69 degrees - slack for the time - and its travel was minimal. Two reasons why it didn't share its relative's negative traits when descending and braking. - Pro's Closet photo

The beginning of the end: Rocky Mountain's 1998 2XS was the carbon/kevlar version of their Pipeline freeride bike. It featured a 150mm-travel Sweet Spot rear end, a 100mm-stroke Marzocchi Z1 BAM fork, a Fox Vanilla shock and a carbon/Kevlar front section. Its adjustable head angle ranged from 71 to 69.5 degrees. It was the only URT in the range, which featured three conventional suspension models covering DH, trail and XC racing. - Rocky Mountain image



Nowadays, people have mostly given up standing while climbing because their bikes are so mushy. Not me! I use ALL my muscle groups on my Zorro single speed. I only put gears on it if I'm nursing an injury. It's fixed my back issues, knee issues, neck issues, and made me stronger than I've ever been. — John Castellano John Castellano's Zorro, son of Szazbo has become a secret weapon for single-speed riders. - John Castellano photo

mountain bikes began to take root around 1992, when suspension forks had 50 millimeters of travel and leaked oil, rim brakes were still the rage, and big tires measured 2.125-inches. Most of the sport's Illuminati were hybrid mountain bikers who had transitioned into the mountain bike industry from road or BMX racing, so they had just come to terms with the RockShox revolution. If one considers that much of road riding and almost all of BMX is spent pedaling out of the saddle, you may then imagine how vehemently opposed both the media and mountain bike makers were to adding rear suspension to their beloved hardtails. Symposiums were staged to denounce the demons of dual suspension, which were easy targets. Fairly rated by today's standards, rear suspension designs at the time fell somewhere between okay and pathetic.John Castellano, a young engineer and upstart cyclist, was a fence sitter in the dual-suspension debate. Being a power-nerd, Castellano believed that rear suspension was here to stay, but he also cut his two-wheel teeth on hardtail mountain bikes and was unwilling to give up the solid feeling underfoot that a rigid rear triangle delivers under power - especially when sprinting out of the saddle.It worked exactly as he imagined. Castellano hacked up a Redline hardtail and built some prototypes, from which he learned that there was a sweet spot created by the height of the swingarm pivot and the rearward location of the bottom bracket which provided what he believed to be the best compromise between (you may have guessed) firm pedaling and good suspension action. He applied for a patent and trademarked his suspension, "Sweet Spot."If imitation is the most sincere form of flattery, Castellano would have been ecstatic when two high-profile bike brands worked around his patent with their own takes on the URT concept. Trek's 9000, its first break into the rear suspension fray bombed horribly, but the Wisconsin manufacturer found redemption when it mated its new OCLV carbon process to an aluminum URT rear suspension.The futuristic Y-shaped front section and its up-to-the-minute rear suspension captured the imaginations of mountain bikers. Many of them had grown tired of the time-worn hardtail, but were reluctant to abandon its road-bike pedaling traits to learn the new skillset required to master a dual-suspension bike. The Y-frame was a URT, and if you believed the press, every URT bike pedaled like a hardtail.By far, the most memorable non-Castellano URT was also the least understood. The Klein Mantra was designed by Darrell Voss, the suspension guru who recently surprised the sport with his breakthrough Naild R3act system. Klein's aluminum hardtails were world-renowned cross-country racers and Voss was keen to build a competitive dual-suspension machine that could uphold their legacy. Voss recognized that he could get away with more suspension travel using the URT without paying a penalty in the pedaling department, so he penned the Mantra with five inches of rear-wheel travel. That may have been the Mantra's undoing, because in some ways it outstripped many downhill bikes of the time, suggesting that Voss's XC racing bike could double up as a crack descender.In its intended role, the Mantra was a winner from the start. It climbed like a frightened monkey, sprinted well, and was ultra comfortable spinning in the saddle over the flatter sections of trail. It looked fast too. The frame was a single, ovalized aluminum tube that connected the head tube with a short stub of a seat tube. The swingarm pivoted on large bearings about six inches ahead of the seat tube and that was it. The aluminum swingarm drove a Fox air shock that was tucked behind the seat tube. It was about as simple as a dual-suspension chassis could be built, and its ability to level choppy surfaces made the Klein a favorite among 24-hour competitors because it could maintain a high pace without punishing its rider. Many Mantra owners wax poetic about their bikes to this day.The dark side of Klein's Mantra was, to some extent, the downfall of the URT concept as a whole. The two features that gave the Mantra its extraordinary pedaling performance: its high swingarm pivot location and biased bottom bracket position, interfered with its descending and braking performance and often at the worst possible moments. When descending out of the saddle and hard on the front brake, the rider's mass would push the cranks towards the front wheel, extending the shock, shortening the wheelbase and effectively steepening the bike's head tube angle. None of those traits are helpful while negotiating a technical downhill. All of them at the same time are just plain scary.The main culprit was probably the Mantra's steep head tube angle (71 to 72 degrees, depending upon the fork), which was the norm for XC at the time. We would learn later that head angles had to be much slacker to compensate for the variables introduced by rear suspension. Had Voss and his URT counterparts been armed with that information, it was doubtful that it would have extended the life of URT suspension.John Castellano's suspension revolution had reached its zenith by 1997. Mountain bikers had lost enthusiasm for dressing in spandex and blowing their lungs up trying to chase each other around a dumbed-down circle of dirt. Cross-country was dead and the dual-suspension bike had become the catalyst for a new, more aggressive riding style. Riders wanted rear suspension that worked best while standing and were willing to climb more slowly if that's what it took to enjoy the descents.Rocky Mountain made the most convincing attempts to carry URT suspension forward with its Speed, XS, and Pipeline freeride bikes, but in the end, it became clear that URT could not progress at the pace of new-school riders. Trek purchased Klein, and shortly afterward the Mantra was dropped from the range. Trek's famous URT was also stricken from their record books as soon as they launched the conventionally designed Fuel. Ibis was sold to a consortium who ran the brand into the ground, and the URT was gone as fast as it blossomed.Castellano's dream would have faded into oblivion before the new millennium arrived if it had not been resurrected by a most unlikely band of misfits. John Castellano said that he still does a brisk business building Szazbo and BowTi replicas and also supports Ibis owners with spares. The Sweet Spot's chainstay-mounted bottom bracket eliminates chain growth, and its exemplary out-of-the-saddle pedaling make it one of the only dual-suspension bikes suitable for single-speed riders.Hindsight is always 20/20. Many are quick to condemn the Unified Rear Triangle concept as a dark chapter in the history of the mountain bike. At that time, though, URT's visionaries were responding to the status quo, a very different audience who embraced the concept of part-time suspension and happened to represent the majority of the sport. History proved them wrong, but before URT went down in flames - for one brief moment - the odd-looking machines outsold conventional suspension bikes by embarrassing margins.