MOUNTAIN BIKE ACTION TEST

FLOATING DRIVETRAIN
KLEIN
Thereīs a storm brewing from the north

On this planet, there are remote islands so isolated that the animals and plants transformed into totally separate species. The human cultures of these islands, if they existed at all, developed tools, rituals and social customs that mimicked no others on earth. What do prehistoric Gilligan Islands have to do with mountain bikes ? The Pacific Northwest ! More distinctly, the bicycle industry as it has grown, nurtured and configured itself in the Pacific Northwest. This group of American and Canadian bike builders live in a subtropical rainforest, eat banana slugs and wild mushrooms and are surounded by a mammoth aerospace network. These Robinson Crusoes of cycling live in a small groups, waiting for one of the three days of sun a year, huddled around espresso bars--in short, the perfect atmosphere for dreaming up new designs and making plans. More often then than not, the huddled java junkies try to reinvent the bicycle. One of the tribes of the Pacific Northwest island chain is the Klein Bicycle Corp.
Gary Klein was originally a road bike builder. Through no fault of his own, the mountain bike revolution didnīt reach the rainforest until its formative days were almost over.

Klein wasnīt in on the ground floor, so when he began to produce dirt bikes, they were unlike all others: hugetubed, welded-aluminum monsters with smooth joints and sugar-candy colors. The Klein tribal shields that were hung over the wigwam hearth were inscribed, "Rigidity and light weight at all costs." Time passes uneventfully, as it often does on islands, and while the outside world was expousing the wonders of Rock Shox and experimenting with rear suspension, Klein had formed a religious cult based on the totem of eking off weight and megalithic aluminum structures in the form of headsets and rigid forks. Klein, along with the rest of the Northwestern bicycle tribes, would have totally missed the age of monkey-motion, if foreign NORBA racers had not settled in the area. Call it cultural impurity, but once the suspension seeds of the outside world were planted, the bicycle builders of the rainforest began to adopt, ever so slowly, these new ideas into their own designs. Poisoned by full suspension, the tribal structure, its totems, worshiped icons and secret society broke down. Even the mighty Klein, staunchest opponent of outside agitators, began to experiment with new suspension concepts and, eventually, the northeast Washington bicycle company emerged from the forest with an entirely new adaptation of the full-suspension bicycle: a high pivot, floating drivetrain rear end, which pivoted on a monstersized tubular aluminum top tube front section. The front was suspended by a Rock Shox Judy fork and the rear shock was a hybrid, oil-damped, elastomerspring unit welded into the frame structure. It was at once both ugly and elegant. The bike bristled with new ideas and yet remained almost monk-like in its austere simplicity. The MBA test crew had ridden floating drivetrain suspension bikes before, but the Klein was an entirely new species.
MBAīs archaeological team was the first to study the Klein suspension bicycle, and when the anthropologists joined the team back in the lab, the department heads had some serious questions relating to the specific adaptations and performance of this awesome-looking suspension bicycle. We rode the Klein extensively, then reconvened to compare notes.

QUESTION ONE: WHY USE A FLOATING DRIVETRAIN ?

The floating drivetrain concept was almost tailor-made for Klein. Kleinīs designers werenīt about to abandon the attributes that had etablished its bicycles as ultra-light demon-ascenders (that means up, not down). They wanted the stiffest bottom bracket--stiff enough would not do ! On a floating drivetrain bike the bottom bracket remains integrated with the drivetrain, totally eliminating the possibility of pivot-induced flex in the most sensitive area of the frame. Because the folks at Klein were born and raised on the hardest of the hardtails, Kleinīs designers were more than willing to sacrifice any pretense of a fully active rear suspension. Suspension was new on the island and they didnīt want to confuse the natives with talk of "active" and "non-active" versions. They wanted a suspension bike that didnīt feel like a suspension bike, one that was a more conventional-feeling climber both in and out of the saddle. By experimenting with the location of the frameīs solitary pivot, Klein could strike a compromise: a high pivot would automatically lock out the rear suspension when the rider was pedaling hard. By moving the pivot fore and aft, the rear suspension could be "tuned" to be less active while standing and more active in the saddle. They settled on a dual-rate (combination of seated and standing suspension feel) which kept the rear end moving about one-third as much when the rider was out of the saddle and almost completely locks out the suspension under power.


QUESTION TWO: WHY IS THE PIVOT SO MASSIVE ?

The longer a lever, the higher the load is on the swingarm bearings and the more a small amount of wear will cause the rear section to become sloppy. Conversely, a wide pivot reduces the loading on the bearings and drastically reduces the effects of bearing wear on the bicycleīs performance. If you have the first element, then you better have the second to counteract it.
There is a limit to how wide the pivot can be. The huge top tube pivot on the Klein taxes this boundary to the max. The effective lenght of the Kleinīs swingarm is from where the rear tire contacts the ground to the top tube pivot.


QUESTION THREE: WHAT ABOUT THAT STEM ?

Klein has been remarkably succesful with its one-piece, TIG-welded, bar/ stem combo. Instead of a conventional headset, the Klein uses very large-diameter sealed bearings, which fit a straight-gauge alloy head tube. The entire setup is bonded with thread-locking compound and needs no further adjustment. There are no conventional stems that will fit its massive steerer tube diameter, so Klein developed a stem with an internal taper-lock binding mechnism similar to the type used to hold machine tools in place. A special alloy wrench is provided to secure or remove the stem via a special nut on top of the stem. A plastic cap hides the nut. The taper-locking stem can be adjusted higher or lower to suit the riderīs taste, and interlocking plastic bellows below the stem are provided to cover the unsightly gap between the stem and the top of the headset. The Klein setup is (as you might have guessed) very light and rigid. The taperlock retention nut takes a great deal of torque to sufficiently retain the stem.


Airing out the Klein: Besides feeling light, the Klein was a well-mannered flier. Most test riders searched for little ripples or natural ramps to loft the fat red bike as often as the terrain would allow. The rear shock was progressive but didnīt have the "bounce" that elastomer units display.

Classy cover-up: To tidy up the head tube area, Klein devised a louver cover-up. There is about 0.75"e; of vertical adjustment in the Kleinīs taper-lock threadless stem.

The sum of its parts: In descsending order, these are the internals of the Klein taperlock stem: (1) the one-piece handlebar/ stem combo has a splined nut on top (the inside tapered), (2) a slotted section that matches the taper inside the stem, (3) the whole thing fits together and slides over Kleinīs oversized steerer tube, and (4) it is tightened into place with a splined wrench. Got that ?

Where the action is: The entire concept of Kleinīs floating drivetrain system is centered around a 10" circle located at the seat tube junction. Kleinīs high-swingarm pivot location goes in the face of most floating drivetrain systems because it allows the suspension to keep on working when the rider is standingJudy, Judy, Judy: In the name of rigidity, Rock Shox abandoned all hopes of using itīs newest microcellular fork in the sticky, gooey, mucky stuff (at least with wide tires). Even gravel would foul the fork brace with Kleinīs ultra-wide 2.37" tires.

QUESTION FOUR: HOW DOES THE KLEIN SHOCK OPERATE ?

The large canister, which houses the shock, is actually a stressed frame member. The small section, which doubles as the front derailleur mount, has a simple oil damper inside. The larger section of the aluminum shock body is a microcellular foam element that works as a spring and damper combination. The shock is driven by a connecting rod that pivots on both ends so the shock can operate in a fixed position.
The hydraulic damper is non-adjustable and a preload collar will come on future models to compensate for different trail conditions. At least three durometer cushions are planned (the design is sensitive to rider height and weight variations).


QUESTION FIVE: DOES IT REQUIRE SPECIAL COMPONENTS ?

Yes and no. Unlike most interrupted seat tube frames, which were designed specifically to accept standard cantilever brakes, Kleinīs reason for using a two-piece seat tube was optimize the location of the shock. The bikeīs rear brake routing is too cramped for cantilevers and needs an offset-pull-type of stopper (like the Paul Crosstop). The rear shock also created a front derailleur hassle. The larger part of the shock body extends into the area of the seat tube that the front derailleur normally clamps onto. Until another alternative can be found, Klein uses a low-level Shimano front derailleur which has a unique, low profile clamping band. Up front, Kleinīs jumbo-sized head tube and steerer tube necessitates that the potential Klein customer purchase the Klein suspension fork and stem from the frame manufacturer (which just happens to be them). The drivetrain will accept all compact drive units, but will not fit standard sized 26/36/46 chainrings.


QUESTION SIX: HOW DID THE KLEIN RIDE ?

Ah, yes, the big question. There was an aura of expectation among the MBA test crew. Itīs inevitable that they would think that a weird-looking bike must follow suit in the handling department. This was not to be the case with the Klein. The jumbo-tube Klein was a mild-mannered gentlemen in every respect. Because the front and rear suspension were sprung by microcellular foam (with hydraulic dampers), the front and rear suspension were well balanced out of the box. In the saddle, the rear end was remarkably supple. Speed didnīt change its mild-mannered temperament. The home-brew shock damper was able to handle a screaming fast fire road without being bouncy at singletrack speed. The folks at Klein attribute this phenomea to the slighty progressive action of the shockīs extra-long bumber stack.
Thankfully, the Klein version of the floating drivetrain softened some of the ride when the rider was standing on the pedals. While the exact proportion of rigidity between standing and seated is being hotly debated by proponents of floating drivetrains, MBAīs staffers all lean to the supple side of the fence when we are out of the saddle. There was enough suspension working in the standing position to reduce the sense that there were two separate rates when riders made the transition between the saddle and the pedals. To find a chink in the big red bikeīs armor, we headed for the rocks (big, jagged and loose ones). If a weakness of a bumper suspension can be found, it is normally while torturing the bike on rocky trails--most bumper suspenders reveal their fatal flaws in the rough and rugged world of baseball-size stones. As it turned out, MBAīs downhill boulder-fest was like Brer' Rabbitīs briar patch. The Klein was able to bomb through the minefield of igneous grapefruit with ease. In fact, It was possible to pick a fairly accurate line through the bash-a-thon.


VITAL STATS
KLEIN FLOATING
DRIVETRAIN SPECS

  • Frame:
  • TIG-welded 6061 T-6 aluminum throughout; floating drivetrain rear suspension, rectangular, S-bend chainstays, oversized, boom tube front section.
     Fork: Rock Shox Judy. Microcellular foam/ hydraulic damping.
     Shock: Klein Microcellular foam/ hydraulic damping.
     Suspension type: High-pivot, floating


    drivetrain, dual-rate suspension.
     Suspension travel: Rear wheel, 3.7";
    front wheel, 2".
     Weight: 24 lb. as tested; frame only
    was calculated at 5 lb.
     Sizes available: 14", 18", and 20" (center to top).
     Components: Front derailleur, Shimano Altus; Rear deraillur, Shimano Deore XT; hubs, Deore XT Parallax (front and rear); Crankset, Deore XT (22-32-42); Cogs, 11 X 28, eight-speed; controls, Deore XT Rapid Fire Plus combos; Brakes,



    Deore XT cantilever (front), Paulīs Crosstop (rear); Rims, 32-spoke, Sun CR 16; Tires, Klein Death Grip, 2.375"; Stem/ handlebar, Klein MC2 one-piece, TIG-welded, 6061 aluminum, 125 mm/ ten-degree rise; Saddle, Flite Titanium; Seatpost, Syncros alloy.
     Frame geometry: Head angle, 71'; Seat angle, 61.5' (special angle to compensate for rider height); Top tube, 23"; Bottom bracket height, 13"; Wheelbase, 41.25".
     Price: $ 3900 (as tested).


    QUESTION SEVEN: HOW DID THE BIKE CLIMB ?

    As anyone who has dealt with the people at Klein could recount, this is one company that believes a bicycle was made to be a rigid-bottom bracket, climbing fool. We went into this evaluation with no doubts that, regardless of how the suspension was hung on a Klein, it would climb. The frame was rigid as could be and the built-in, pedal-induced suspension lockout was apparent the moment we cranked up the first grade. At 24 pounds, the Klein was certainly light for a fullsuspension bike, but it didnīt have a snappy feel, whether the rider was ascending in or out of the saddle. Could it be a slow climber ? We looked at our watches. Our times up our favorite mining road grade indicated that we were doing much better than our senses led us to believe--every-one was a half-minute or so ahead of their hardtail time after an hour of middle chainring uphill work. This indicates that the rear end must have been secretly smoothing out the ride despite the torque-induced suspension lockout feature. Remember those rocks ? Well, we found the Kleinīs Achilles heel while ascending rocky, loose sections. The added effort seemed to eliminate any beneficial effect the rear suspension had, and the rear end reverted to a skittering hardtail, spinning to a halt along with the other unsuspended retro-mounts when the going got tough. we waved goodbye to the "active" suspension bikes as they clambered up and out of sight. Okay, maybe thatīs a word that will get to the island in a few years.


    Cool, but not sweet: Klein is fond of rear entry dropouts because the design allows for a stronger aluminum dropout mount. MBA likes the setup--as long as itīs on another racerīs bike. Quick wheel changes would required much practice.

    QUESTION EIGHT: WHAT WAS MBAīS FINAL WORD ?

    We rode the Klein, raced it, tortured it and actually liked it. There were a few things that we hated, too. The super-wide top tube swingarm pivot was a kneebasher. The red bike would give no indication of its girth until the moment when a rider was negotiating a critical section of singletrack--then, bang ! There is room to narrow the pivot without sacrificing rigidity. We also hated the rear-entry dropouts. They make no sense on a mountain bike. Every test rider had to fuss with the rear wheel and messy chain to line up the axle with the dropouts. Lose 'em and we will take our chances with a bent derailleur hanger later.
    In the final analysis, the Klein did exactly what we expected it to do: (1) climb well, (2) act like a hardtail under power, (3) keep the rider suspended when he was in-the-saddle, (4) handle the dirt like a pro racing bike.
    One test rider described the Klein as a bionic Sling Shot...and in and odd way, the cable-suspended Sling Shot is the only bike that shares the Kleinīs unique handling qualities.

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