Carole Nash
Content Writer
Published: 23rd June 2008

yamaha trx850 hyper proThere are many interesting things to be found in Holland, with cheese, drainage systems and hardcore porn being just the top three of course.

But the Dutch also have some superb motorcycle fettlers dotted around their landscape, with Hyperpro being a good example.

Their treatment of the late, frequently lamented, Yamaha TRX850 twin may not be to your taste, but it is undeniably different, with perhaps the wackiest front end ever seen on any bike in the last ten years. Roland Brown rode this X files special.

If anyone needs convincing that alternative front suspension systems have a future despite high-profile failures such as the Bimota Tesi and Yamaha GTS1000, a blast round the canal-lined country lanes of central Holland on the Hyperpro Troll TRX850 would surely do the trick. These roads are narrow, bumpy and twisty – a demanding test of suspension and handling. And the TRX, with its unique single-shock front end, was a brilliant bike on which to attack them.

Part of the attraction was the way the mildly tuned parallel twin engine punched out torque, but it was the TRX´s new chassis that made most impression. The bike´s steering was fast and light yet dead stable, the front suspension soaked up small bumps yet felt taut when cornering and under heavy braking, and the whole front end gave almost uncanny feedback on precisely what the sticky Pirelli Dragon Corsa was doing.

The Hyperpro Troll TRX850 is the result of a collaboration between two talented 35-year-old Dutchmen: Hans Rinner, who runs suspension specialists Hyperpro, and Hans Oosterhoff, whose firm is called Troll Engineering. They studied design together at college and later worked together at White Power, where Oosterhoff designed a promising single-sided front suspension system. It is this that has now been further developed into the new Troll set-up.

Given Yamaha´s misfortune with the GTS1000, it´s ironic that the basis of the bike is another Yam, the TRX850 parallel-twin. The TRX´s lines are clearly visible in the Hyperpro bike´s fairing and fuel tank, which are standard. The engine is also basically stock, but the same certainly can´t be said of the hefty, 60mm diameter lengths of yellow steel tube that take the place of the Yamaha´s frame. (The TRX´s swing-arm pivot, swing-arm and steel rear subframe remain, but the main trellis now holds a pot-plant in the Hyperpro office near Utrecht.)

Oosterhoff´s Troll front suspension set-up has little in common with the RADD system that Yamaha used for the GTS1000, although both are hub-centre designs. On the GTS system, the large chassis strut running from the engine area to the hub-centre pivots. But the yellow tube leading to the Troll bike´s front wheel is a rigid part of the frame.

Instead, the Dymag wheel is bolted to four grooved castors, and slides up and down a parallelogram-shaped metal block on the left side. (It´s this movement that gives the Troll Linear Guiding System its full name.) Wheel travel is controlled by a single vertical shock on the right side.

The shock unit is one of the twin uprights (the other consists of a narrower yellow tube and the parallelogram) that provide steering, by coming together to pivot at the steering head, then splitting again to hold the clip-on handlebars. (Imagine it as a person with arms raised: the arms are the handlebars, the waist is the steering head, and the legs are the lower struts, with the shock unit being the right leg.)

The steering head is formed by another section of the large-diameter yellow frame tube, which curves upwards to grip the handlebar/shock assembly at its waist. This tube also supports components such as the headlight assembly, fuel tank, radiator and coils.

There´s no denying that the asymmetrical Troll system looks ungainly compared to the neat simplicity of telescopic forks, but it certainly has plenty of theoretical advantages. Most important is the lack of a telescopic system´s friction, notably under heavy braking.

´When a bike is really braking, even good forks like WP or Ohlins bend by 20mm,´ says Rinner. ‘The force needed to overcome that friction is 80kg, which has to be put into the tyre first, so the tyre gets a really hard time. With our system the forces are fed straight into the frame, and you control everything with the spring and the damping – that´s a big advantage.´

Because the Troll system´s braking forces are fed into the frame near the engine, instead of into the steering head area as with telescopics, the frame itself can be considerably lighter. The lack of a bulky steering head also frees up room for the airbox and other parts.

The complete Troll system is much more rigid than a pair of forks, giving a more precise steering action. This TRX prototype´s front end also has 0.5kg less unsprung weight, while its reduced moment of inertia (partly due to the absence of triple clamps and upper fork legs) allows easier direction changes. Finally it is possible to have a very steep steering angle, which improves low-speed handling, yet a conventional amount of trail, to aid high-speed stability.

All of which sounds fantastic – so long as those theoretical advantages are borne out by performance on the road. And the Hyperpro TRX850, which at 176kg is 14kg lighter than a standard TRX, certainly works well enough to suggest that Rinner and Oosterhoff are onto something.

From the moment you climb aboard there´s no doubt that this is one very different motorbike. The original clocks are in place, but there´s a small digital speedo and temperature gauge in the cockpit (the normal speedo runs off the front wheel, so doesn´t work). The ignition switch is set into the top of the left handlebar. The U-shaped handlebar tube curves upwards to position the clip-ons 5mm lower than standard, for a not-too-radical riding position. Steering lock is limited, but not drastically so.

The prototype´s 849cc watercooled, 10-valve parallel twin engine is internally standard, boosted only by a neat twin-silencer exhaust system (made by Dutch dealer Star Twin), a pair of 41mm flat-slide Mikuni carbs and a new ignition box. Those mods alone had increased peak power output by 10bhp to 80bhp at the rear wheel, Rinner said, and given more torque throughout the range.

The 270-degree crank motor fired with a rich, Ducati-like bellow from the carbon cans, but once under way that noise was almost drowned out by the loud induction whistle from the flat-slides. Straight-line performance was a real-eye opener, the Hyperpro bike leaping forward from low revs with enough force to lift the front wheel, and powering crisply through the midrange towards the 8000rpm redline and a top speed of 130mph plus.

My first impression of the handling was that it felt very normal, much more like a telescopic than a GTS1000-style set-up. The Hyperpro bike absorbed bumps well without feeling particularly soft, partly because it was originally designed for Japanese twins racing, and so had been built with 90mm of front wheel travel instead of the more normal 110-120mm that would otherwise have been provided.

The front end felt superbly well-controlled, though, the front shock – an Ohlins body, modified and fitted with a Hyperpro rising-rate spring – giving a huge amount of feedback. The rear shock, also an Ohlins/Hyperpro combination, was also spot-on. (Hyperpro´s main business is supplying rising-rate fork and shock springs to a growing worldwide market.)

Steering was very light and precise yet, as promised, the TRX – aided by a sophisticated Hyperpro steering damper – remained stable even when cornering on bumpy roads. It was also rock-solid in fast sweepers, and didn´t even twitch when I backed off the throttle in the middle of a 100mph curve. Rake and trail can be varied independently, giving the system plenty of potential for fine-tuning, but no adjustment was necessary.

Predictably the Troll bike was at its best under hard braking. Although the TRX tended to stand up slightly when braked into a corner, stability and control remained excellent. Unlike many forkless systems, this one does allow a fair amount of dive under braking – but with the advantage that the suspension continues to work properly. ‘Brake dive is good, provided the suspension is working, because it puts more force on the front tyre and allows you to brake harder,´ says Rinner. ‘Without dive you just skate over the bumps.´

Given this advantage it´s ironic that one drawback of the Troll system is that only a single front disc can be used. Not that this was a handicap on the Hyperpro TRX, which stopped mighty hard thanks to its combination of six-pot Alcon caliper, specially made 340mm PFM fully-floating disc and ultra-sticky Dragon Corsa tyre.

Rinner and Oosterhoff are confident that using a single disc would not be a problem for racing, either, and their plan is to prove the system on the track. Hyperpro have already provided springs for riders including Ralf Waldmann, and the two Hans are talking to several teams, some in grands prix, about using a Troll system next season.

´Our plan is to win some races to give credibility, then to produce a series of road-bikes,´ says Oosterhoff. ‘With this system we could save 8 or 9kg in a racebike´s weight, which alone would be very valuable. We have also developed a similar system for the rear which could save several kilos more.´

Although this first prototype was inevitably expensive, further bikes would be less so. ‘Another one bike like this would cost maybe NLG60,000 [£25,000] but if we were to make 20, then NLG40,000 [£16,000],´ says Oosterhoff. Our system is no more expensive than front forks if you make the same numbers.´

Many cynics will doubtless remain unconvinced. Alternative front suspension systems had their chance and blew it, they´ll say, with the Elf, the Tesi and the GTS1000. But alternative systems are beginning to make their mark, notably BMW´s Telelever. And the Troll system (which, its makers claim, outperforms Telelever in stiffness, friction and unsprung weight) is certainly a hugely promising design with several distinct advantages.

If Rinner and Oosterhoff can provide the racing success that will overcome public resistance, the Hyperpro Troll TRX850 may yet turn out to be the face of motorcycling´s future.

Get Yamaha motorcycle insurance for the yamaha trx850 hyper pro.

Vital Statistics 
Engine Liquid-cooled parallel twin
cc 849cc
Claimed power (bhp)
Compression ratio

Transmission 5 speed
Cycle parts

Carburetion; Twin 41mm flat-slide Mikunis
Clutch; Dry multiplate
Front suspension; Troll system, Hyperpro/Ohlins damper, 90mm (3.5in) travel, adjustments for preload, compression and rebound damping
Rear suspension; One Hyperpro/Ohlins damper, 130mm (5.1in) wheel travel, adjustments for preload, compression and rebound damping

Front brake; six-piston Alcon caliper, 340mm disc
Rear brake; single-action caliper, 245mm disc
Front wheel; 3.50 x 17in; cast magnesium
Rear wheel; 5.50 x 17in; cast magnesium
Front tire;120/70 x 17in Pirelli Dragon Corsa radial
Rear tire;180/55 x 17in Dragon Corsa radial
Rake/trail; 18 degrees/90mm (3.5in)
Wheelbase;1415mm (55.7in)

Dry weight; 176kg (387lb)
Instruments; Speedometer, tachometer, temp gauge, voltmeter, lights for turn signals, neutral, high beam, low oil pressure
Top speed 120mph
Fuel capacity 18 litres (4.7 US gals)
Buying Info
Current price