Breaking barriers in more ways than one


Gary Klein is no stranger to controversy. His unique, oversized aluminum bicycles have garnered more than their fair share of praise and criticism, innovation and imitation, as well as aesthetic kudos and ugly-duckling comments, and through it all, Klein bicycles have kept on doing what they do—and doing it better every season.

To the bicycle world, the name “Klein” stands for “fat tubes.” Gary Klein turned his college education into a business and managed to set the design world on fire. The fat tubes of the Klein, which are now a trademark, weren’t always so readily accepted. What the scoffers didn’t realize was that the jumbo aluminum tubes of a Klein allowed it to be as strong as steel, exceedingly rigid and marvelously light. In today’s era of alternative materials (carbon fiber, titanium, magnesium and matrix composites), a lot of people forget that aluminum is the most successful alternative ever used. Gary Klein not only recognized the alloy’s potential, but he spearheaded the design movement that made its use possible.

Fat boys: If the forks look exceedingly beefy, it’s because they are made out of aluminum. Klein is the first major American manufacturer to produce oversized alloy forks with an aluminum steerer tube. There’s plenty of tire clearance and solid feel.


No, Gary Klein didn’t invent the aluminum bicycle, but he invested in it. Time, energy, creativity and innovation have advanced the aluminum bicycle from those early cobby and crude beginnings to the art form that it is today.

The 1990 Klein Attitude is a bike that has benefited from Klein’s unfailing devotion to aluminum. A close perusal of the Attitude is like taking a trip through Gary Klein’s scrapbook, for it abounds with all the innovations, tricks and craftsmanship that have made Klein the most popular oversized aluminum bike on the off-road rider’s wish list. Gary Klein isn’t living in the past, though; he is moving forward, and in a year that will see designers serve up radical new elevated chainstay bikes, titanium featherweights and multi-material composites, the Attitude outshines them all with its evolutionary new concepts.
Take a tour of the Klein Attitude with the MBA wrecking crew.


What does it weigh? It is light, and it is honestly light. What do we mean by that? In the past we have tested super-light Kleins, but a lot of the weight savings came with the use of off-road mirrors sleight-of-hand tricks, like Huret Jubilee derailleurs. Jubilees are wonderfully light but not too durable. Past Klein “diet” bikes didn’t weigh much, but what you saved in pounds you lost in time looking for replacement parts in roadie shops. Not so for the Attitude!

Hitting the infallible MBA scales at 23.75 pounds (with water bottle, cage, clips and straps), the Attitude is incredibly airy. There are no time-trial parts, drilled derailleurs or French components on the Attitude. It is equipped with real parts, the kind you could actually risk going off with for a day in the boondocks.

Loose nuts: You never have to adjust the Klein headset. You couldn’t adjust it even if you tried. It uses 1.6-inch aircraft bearings that are pressed and Loctited into the enormous steerer tube. The one-piece bar/stem combo is ultra-light.



Take a close look at the Klein aluminum forks because you are seeing mountain bike history in the making. No other big-name manufacturer would dare put aluminum forks on their bikes—no one! Gary Klein did, and he should be applauded for it. Why? Because all the other builders steered away from aluminum forks due to fear. Fear that the forks wouldn’t be strong enough, that they would fatigue from the flex, and that they would be ugly. The Klein Attitude’s forks are ugly. To make aluminum forks strong enough to take the fear out of riding with alloy blades, you have to make them big. The thought of putting really big forks on their bikes drove other builders away, but Gary Klein has never veered away from anything fat. Fat forks were a natural extension of his original fat frame.

We think that Klein aluminum forks are a bold move. By using 1 5/8-inch tubes spun down, the Klein forks have a constant wall thickness of .058 inches. The steerer tube is a humongous 1 9/16 inches. Given the oversized fork blades and beyond-belief steerer tube, the Attitude’s forks are strong, rigid and light!

Chain-suck: Given the limited clearances that are imposed by the use of oversized aluminum tubes, the Klein has a special Chain Control Device (CCD) that keeps the links from grinding through the bottom bracket.



We shouldn’t even call the Klein’s headset a “headset”. The 1.6-inch steerer tube is Loctited to a set of double-sealed aircraft control bearings. These beefy bearings can handle 1600 pounds of radial load and 3200 pounds of thrust. The bearings themselves are pressed into the largest head tube in captivity and securely Loctited.

How do you adjust the Klein headset? You don’t! It doesn’t need it. A one-piece aluminum bar/stem combo is slipped down inside and tightened with a wedge. That’s it! The bar/stem comes in four different extension sizes—90mm, 120mm, 135mm and 150mm—and weighs only 430 grams, which is less than one tire.

Monopoly: The Attitude uses narrow Dia-Compe 986 cantilever brakes on the rear because they stick out less than the Shimano brakes. The narrow-profile Dia-Compes avoid heel clipping. Good thinking.



If you wanted to buy the Klein Attitude frame by itself, it would set you back $1149. For the bucks, you get the 6061 T-6 aluminum frame, alloy forks, one-piece bar combo, aircraft headset and bottom bracket.

Klein’s frame workmanship has been a thing of wonder over the years. The large, fish-scale, Heliarc weld beads have been massaged so that they blend nicely into the oversized tubes. The cables are routed internally via nylon housings, and the chainstays are Klein’s personal square-to-round tubing.

Several efforts have been made to improve mud clearance on the Attitude. Most noticeable is the mitered aluminum front fork, which has plenty of wheel clearance. In addition, the chainstays have been bent at a more extreme angle under the bottom bracket to improve what has always been a weak spot on oversized aluminum frames. It is tight under the chassis, and you have to give something to get something. Klein’s efforts to improve mud clearance for the tire have totally eliminated any chainring clearance. The 46-tooth big ring would hit the chainstays if it got the slightest wiggle in it.

In an effort to eliminate chain-suck (and its associated grievances), a Klein Chain Control Device (CCD) is bolted under the bottom bracket. The CCD is a steel deflector plate that fits snugly against the chainrings to keep the chain from wedging into the aluminum BB shell in a miscue.

Out back, the Klein has rear-entry dropouts. The advantage of mounting the wheel from behind on an aluminum frame is that there is more meat around the derailleur hanger, which tends to be a weak spot on alloy frames. The disadvantages are evident when you remove or mount the wheel. With the axle pulling out behind the jockey pulley, you have to disengage the derailleur by hand.

The Attitude jumps when you pedal, it whips when you jump, and you smile when the terrain requires quick movements.



Our test frame was a 19-inch model (measured from the center of the bottom bracket to the effective level top tube), but with the radical slope of the top tube, some manufacturers would call it a 17.25-inch frame. Take our word for it, it’s a 19. The head angle is a contemporary steep 71 degrees, while the seat tube is a relaxed 72.5 degrees. Relaxed seat angles weren’t popular with the “steeper is better” crowd over the last few years, but are definitely making a comeback (it makes you want to congratulate the builders who never strayed from them).

Top tube length was a little shorter than many test riders would have liked (22.5 inches) and was mated to a 4-inch-reach stem. The standover height (measured from the ground to the top of the top tube at the midway point) was 29.25 inches. With this stand-over height, our Klein frame could accommodate riders with 30.5-inch to 33-inch inseams. It is basically a medium-length top tube bike (with a medium reach stem) that gets its rider adaptability by the use of a sloping top tube.

Chainstays are 16.75 inches long and are perfectly mated to the slack 72.5-degree seat angle. Remember that a slacker seat angle positions the rider’s weight further back than on a steep (73- to 74-degree) seat, so ultra-short chainstays aren’t necessary to guarantee good climbing traction.

The Klein is not a show bike that will crack or explode when you take it off
its pedestal.



We did like the three water-bottle mounts. That is something that every serious trail bike should have. The extra water-bottle boss can carry more fluid for expeditions or serve as a mount for pumps, toolkits, air cartridges or chain lube. Another plus was the Klein fender mounts (people do ride in rotten conditions). The three water bottles and fender mounts would make the Attitude a great expedition, touring or camping bike, except for one thing—no rack mounts.

Our test bike came with a Lycra-covered Turbo saddle. We have a box full of ripped Lycra saddles in the palatial MBA workshop, and expect the Kleins to be joining the pile after the first big crash. We prefer saddles that are covered better than the riders sitting on them.

Chainring clearance is so severely limited that the 46-tooth big ring is the biggest ring the Klein will accept without some ground aluminum chips coming off the chainstays. Among the many reasons that elevated chainstay bikes were developed was to give mud clearance, chainring clearance and to lessen the damage caused by chain-suck. The Klein Attitude gained mud clearance at the expense of chainring clearance and added a steel plate to cut down on chain-suck destruction. The bottom bracket area is a compromise under any circumstances, but the larger tubes of aluminum require more compromises. Overall, Gary Klein made the best of a crowded situation, and the Attitude addressed two out of three problems.



No need to hedge any bets; we like the Klein Attitude. Sure, we have a few quibbles, but that doesn’t lessen the sheer joy of throwing a leg over a bike that is on the cutting edge of bike design. You have to respect Gary Klein for his willingness to sacrifice the traditional look of the classic bicycle to gain some improvement. The fat look, whether you are talking about frame tubes, forks, headsets or stem/bar combos, is stamped with Klein’s signature. Big doesn’t mean heavy, however. At 23.75 pounds, the Attitude is 3 pounds lighter than most hardcore mountain bikes and as light as the majority of wonder metal bikes.

It’s not a show bike that will crack or explode when you take it off its pedestal. The light weight wasn’t attained by taking shortcuts in strength. It’s a real dirt bike.

In a nutshell, the concept behind the Attitude is that the bigger you make the tubes, the thinner you can make the walls. Thin-walled, oversized tubing is lighter and stronger than regular-diameter, thick-walled tubing. The formula is a matter of finding the balance among fat, strong and light. That’s what Klein is famous for. The formula is almost proprietary to Gary Klein.

We’d give a rough estimate that Klein’s oversized aluminum tubing offers the equivalent strength and feel to 1.125-inch chromoly (at quite a weight savings).


We said it was a real dirt bike, and we meant it. The shortish top tube gives the Klein an agile feel that plays perfectly with the fact that the Attitude is agile. The weight (or lack of it) is noticeable immediately. For rollies that you burned over on your 27-pound bike, you can now skim the top in a gear taller on the Attitude. It jumps when you pedal, it whips when you jump, and you smile when the terrain requires quick movements.

We thought, and we had pretty solid theoretical support, that the Klein would be harsh. Our expectation was based on the fact that the oversized tubing (even if it is made out of aluminum) was going to make a rigid, non-absorbent and stiff bike. The innovative aluminum forks have to be stiff, we figured, because they must be over-engineered, and any bike with a 1.6-inch steerer tube is going to resist giving. Not so. The complete bike responded to the whoops and undulations of rough ground with a firm but pliant feel. It was no rubber band, but it was softer than we expected, which proves that theory in bicycle design is not as important as the magic that a builder can add to a frame.

Good geometry, light weight and solid components (Shimano Deore XT) make the Klein one of the finest-looking, most innovative and detailed bikes we have tested in a long time. It’s almost a shame to take this work of art into the brush and rocks of the real world, but it would be a bigger crime not to enjoy every moment at speed. After all, dings and scratches are signs of off-road happiness. What was the best thing about the Klein? Not having to stop and tighten the headset—ever!

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