New 2019 Yamaha Niken steers a radical path
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(Yamaha)

New 2019 Yamaha Niken steers a radical path

The world’s first leaning three-wheel motorcycle is an expression not only of engineering prowess, but of a real passion for riding.
When Yamaha debuted the MWT-9 concept three-wheeler at the Tokyo Motor Show in October 2015, many were impressed by its technology and almost unnerving, mantis-like visual presence. Yamaha has a history of stunning concepts for the Tokyo show, so it’s likely few thought a production version would ever see real roads. But two years later at the same show, Yamaha unveiled the world’s first 3-wheel leaning motorcycle and amazingly, production of the Niken began in the second half of this year.
 
The Niken is radical—a brazen mechanical-engineering statement, in the vein of Yamaha’s 1993 forkless GTS1000. Based at Yamaha’s HQ in Iwata, Japan, the main Niken development team was comprised of eight Yamaha Motor Company (YMC) staff (below), four of whom were engineers. Takahiro Suzuki was the Project Leader for Niken development, with chassis development handled by Ryuta Mitsuoka.

 
(Yamaha)
Meaning 'two swords' (‘ni·ken’) in Japanese, the label refers to the two front wheels carving up twisty roads and originates from a 17th-century style of swordsmanship which proved a revolution in combat. Based on the popular Yamaha Tracer 900 sport-touring motorcycle, the Niken is powered by a similar 847-cc, liquid-cooled, four-valve DOHC crossplane-crankshaft 3-cylinder engine that’s been retuned via fuel-injection mapping and a slightly heavier crank.
Clever Ackermann parallelogram
Invented in 1817 by German carriage builder Georg Lankensperger (and named for Rudolph Ackermann, who filed the patent), an Ackermann linkage permits wheels tied by an axle to independently track the required radius of a turn, as the inner wheel must follow a tighter radius than the outer to prevent wheel slip or scrubbing. Yamaha calls its Ackermann setup the Leaning Multi-Wheel (LMW) system. The goal on the Niken was more riding fun with less stress, and it was keenly engineered so that experienced motorcyclists would not have to alter their riding style.
 
The Yamaha LMW parallelogram (below) uses Ackermann steering geometry with separate steering and lean axles, a 20-degree caster angle and a fixed track of 410 mm (16.1 in). An offset steering knuckle and tie rod keep the geometry consistent throughout the full range of lean regardless of steering input, and the parallel linkage connects to two fork stanchions mounted to the outside of each front wheel to create the fixed geometry. This allows the front wheels to turn and articulate in their own radius, even during lean.

 
(Yamaha)
On the Niken, maintaining low friction in the parallelogram was key in creating a natural feeling as the motorcycle moves throughout its roll axis. To accomplish this, the LMW linkage uses a combination of bushings and tapered-roller, ball and spherical bearings. All adjustments are factory set, with the only provisions a front-wheel “toe” adjustment and a steering-head adjustment to correlate handlebar-to-wheel alignment.
 
The engineering team noted that reaching the Niken's maximum lean angle of 45 degrees was one of its biggest challenges, in concert with creating an Ackermann setup that still behaves like a normal motorcycle — including requisite counter-steering inputs. The innate stability provided by the two-wheeled front end allows for aggressive chassis geometry, including a trail specification of only 74 mm (2.9 in), 25% less than a typical sportbike.
Two of everything
Most modern streetbikes feature a 17-in front wheel, but the Niken uses two 15-in front wheels fitted with 120/70R15 V-rated tires specially developed by Bridgestone for the Niken. Each front wheel combines with a 298-mm (11.7-in) brake rotor and four-piston radial caliper. Along with reduced inertia, the smaller front wheels and outboard-mounted forks provide the space required for steering and suspension articulation, including the 110 mm (4.3 in) of suspension stroke.
 
Each of the two stanchions for the front wheels serves a different role. The 43-mm (1.7-in) rear stanchion provides shock absorbing capability with full preload, compression and rebound-damping adjustability. The 41-mm (1.6-in) front stanchion provides direction setting and holds the wheel/brake assembly in alignment. The left and right stanchions can be adjusted and operate independently.
 
The Niken’s unique chassis features an investment-cast-steel head tube connected by a steel-tube frame to the aluminum swingarm-pivot assembly, and an aluminum rear subframe. The 552-mm (21.7-in) aluminum swingarm is 15 mm (.6-in) longer than the Tracer 900’s for increased stability and compared to the Tracer’s 1500-mm (59-in) wheelbase, the Niken’s is only 10 mm (.4-in) longer but the rider sits 50 mm (2 in) further rearward, helping promote a near 50:50 front-rear weight distribution with the rider on board.

Yamaha claims a 263-kg (580 lb) fully-wet weight for the Niken, which is 70 kg (155 lb) more than the same spec claimed for the Tracer 900. A slightly shorter transmission secondary ratio (16/47; 2.938:1 vs. 16/45; 2.813:1 for the Tracer) helps maintain acceleration targets and the Niken provides the latest in electronic controls, including a quick-shift system, ABS, cruise control and traction control. Beyond the additional traction provided by the dual front wheels, it’s engineered to operate like a typical sportbike.
 
Industry followers should note that at the same 2017 Tokyo Motor show that saw the debut of the production Niken, Yamaha unveiled its electrified MOTOROiD concept. Yamaha has cannily described the MOTOROiD (below) as an “unleashed prototype” and it recently won a Gold honor at the prestigious International Design Excellence Awards (IDEA). We can’t wait to see what Yamaha unleashes next, and if the Niken is any guide, don’t be shocked if it’s electric.


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