The Emilia Romagna region of Italy is a melting pot for the Italian motorcycle industry. Positioned in the middle of this province, also known as the “terra dei motori” or the land of engines, sits the motorcycle company known as Bimota.
In September 1972 the now famous designer Massimo Tamburini crashed his Honda 750 Four at Misano racetrack — the stack left him with three broken ribs. While recovering from his unfortunate incident, he constructed a tubular steel frame to handle the horsepower then being produced by the Japanese bikes.
The frame he constructed lowered the centre of gravity and reduced the weight of the original Honda. Called the HB1, the first Bimota was born. Bimota’s name is derived from its founders’ initials: Bianchi, Morri and Tamburini.
Bimota has a rich racing heritage and has carried such great names as Virginio Ferrari, Davide Tardozzi, and Randy Mamola. Also who could forget Anthony ‘Go Show’ Goberts awesome WSBK victory at a wet Philip island in 2000 aboard the Bimota SB8R!
Born from a young university graduate’s mind, it was Engineer Pierluigi Marconi’s university thesis (Tesi in Italian) that directly led to the Bimota Tesi 1D hub-center steered motorcycle in 1990, the 1, 2 and 3D standing for the various Ducati engines used in the models.
Designed by Tesi Engineer Andrea Acquaviva the 3D looks similar to its predecessor the 2D. However Andrea started with a relative clean sheet of paper to produce a bike that corrected the 2D’s drawbacks of limited steering lock – improved from 18 to 23 degrees, a repositioned front shock to clear the rider’s knees, a narrower build and a simpler steering system to improve steering feel.
The Tesi 3D E in this test is an evolution of the 3D which includes a further revised front shock position. The 3D pull-rod mechanism hydraulic suspension which was located low beside the engine has been replaced on this evo version with a more traditional spring over damper shock directly mounted on the front swingarm translating into more responsive damping of the front end. The evo version also has heaps more carbon fibre and a very handy STM slipper clutch.
Acquaviva has wrapped the Desmo donk in a pair of Omega-shaped aluminum spars providing mounting points for the front and rear swingarms. A tubular-steel subframe locates the steering head and its carbon fiber rear end with a solo seat.
The Design team used the Delirio’s exhaust, headlight, dash and added a hub-center front end with the new shock and steering link layout.
Unlike the Tesi 1D, whose steering linkage went across the frame from the left side of the bike to the right, the 3D retains all its rocker-arm steering linkage on the left. This helps reduce steering friction and improves the all important connection from the handlebars to the front tire contact patch.
The 3D Tesi E uses Ducati’s 1079cc Dual Spark motor producing 100 Desmo air-cooled horsepower with 100Nm of torque. The placid nature of this older motor doesn’t really fit with the 3D Tesis high tech mega detailed chassis.
However it makes the bike very easy to ride and it gets along quite nicely, if you keep the motor on the boil due to the bikes excellent handling. The engine power delivery is reasonably linear and smooth although a little soft so you definitely have to keep the revs up to maintain a decent pace.
A set of open pipes and some engine re-mapping would certainly add to the ponies and sharpen up the power delivery. The motor is pretty quiet too, and by the day’s end I was hanging for some Ducati Desmo tones.
The electronics are from Bimota and the motor red lines at 9,000rpm. We bounced off the limiter a few times before getting used to the relatively low rev ceiling. The Tesi’s Ducati gearbox is reasonable. A little notchy, but well spaced gears made the best of the motor. Engine braking was excellent with no rear wheel lock ups, the STM dry slipper clutch working well.
The 3D has extra connotations best described as a 3D feast of motorcycle engineering jewellery! Every time you look at this smorgasbord of aluminium, chromalloy, and carbon fiber you spot some new intricate detail. The bike is one of only a handful in the country being ridden, the others are in living rooms as art pieces.
What’s it like to ride? After testing all of the latest superbikes recently, I had a fresh feel for the latest motorcycling technology, and the 3D Tesi E was a big surprise.
Bimota set the bike up at the factory to suit the owner and his 100kg frame. Thus I spend the morning tuning spring preload and damping rates to suit my Leprechaun-esque 75kg.
The Extreme Tech suspension had a good range of spring preload, compression, and rebound adjustability although I did find the clickers a little insensitive to change compared to the latest European superbikes.
This bike is a lot of fun, and whilst I was getting canned down Lakeside raceways straightaway by the more powerful machines sharing the track, the 3D Tesi E strengths of stability, agility and powerful progressive brakes (Brembo 4 pot radial callipers combined with 320mm discs) meant I could make up heaps of time, especially through the high speed turns, chicanes and by trail braking deep into the corners.
Normally motorcycle stability and agility are trade-offs, as front end geometry with a larger stable trail effectively reduces the bikes roll rate making it harder to turn. The 3D Tesi was very stable yet also very manoeuvrable!
Not quite the Panigale level of agility, but very respectable for what is effectively a 20 year old design. The 3D is very narrow and reasonably light with a 167kg dry weight. This together with lightweight OZ wheels and the bikes centralised mass all contributed to excellent handling.
At the handlebars the 3D Tesi E generally feels similar to a conventional forked machine. Under acceleration and through high speed turns the bike felt impressively balanced and planted.
Through lakesides high speed Turn 1 there was some head shake but nothing to ever get concerned about as you can feel the lightweight OZ wheels low mass would never translate into anything serious. Impressively, no steering damper was fitted or needed.
However differences start to become apparent when you begin braking. There is no noticeable front-end dive and also minimal pitching, the bike remaining relatively flat, minimizing weight transfer to the front tire.
The Tesi feels more stable under heavy braking than a conventional machine, which inspired confidence and encouraged some serious trail braking. Turn-in stability is excellent, the Tesi holding its line beautifully.
When approaching the middle of low and medium speed corners, a certain vagueness and reduced feeling with the front tire is apparent. My apex speed would certainly have been slower on the 3D Tesi E compared to the latest European superbikes.
This is probably due to the friction in the multiple elements of the hub-centre steering system and lack of weight transfer to the front tyre. The 3D was so good overall I reckon some detail design changes to lower friction bearings and higher quality Ohlins suspension would be a good step forward.
A dynamic trail system that optimised the steering geometry at this point would also be a tidy evolution to hub-center steering technology that could possibly see it overtaking current conventional superbikes?
Hard braking over bumps is one of the Tesi 3D E strengths as the suspension deals with bumps separately to the braking forces. There is a ton of ground clearance with only the Michelin pilots road tires limiting my bravery.
Also noticeable on the racetrack was a new set of mechanical sounds coming from the front end. A bump on the exit of Lakesides bus stop chicane was creating some unusual vibration through the front trellis swingarm which was a bit disconcerting considering my brief was not to scratch this $50k + piece of motorcycling exotica, however as I got used to the Tesis idiosyncrasies I became more comfortable throughout the test.
Overall I loved this bike, it’s a lot of fun, looks very cool, and handles superbly, all that’s needed is a Panigale motor.
Hub-center steering has the potential to improve the performance and safety of motorcycles because it separates the steering, braking, and suspension forces compared to the typical standard fork equipped motorcycle.
The front suspension, on a motorcycle equipped with a conventional fork, is compressed under braking forces. This also has the effect of reducing the trail (see image below) increasing the motorcycles roll rate or ability to turn, which in turn, reduces the motorcycles stability, compared to a hub-center steering system.
Typical standard motorcycle forks also lack stiffness in comparison to hub-center steering as they act as a long lever to the headstock. This long lever design also transfers large braking forces through the frame headstock which subsequently is required to be very robust, adding to the bike’s weight and high centre of mass.
Hub-center steering is a triangulated design that by nature transfers loads directly to the chassis away from the headstock, resulting in a lighter headstock design. This design also has the benefit of reduced steering flex under heavy braking.
Also, hub-center steering systems typically use a linkage which maintains steering geometry, namely trail, with front wheel travel, negating the adverse steering geometry change experienced when braking on a typical standard fork equipped motorcycle.
The king pin centreline defines the steering axis compared to a conventional forked motorcycle where the steering axis is generally through the headstock centreline.
The 3D Tesi hub centre design has lots of positive handling benefits including low unsprung mass, high rigidity, low steering inertia plus easy rake and trail adjustment.
Hub-center steering motorcycles have been around for a while now and have been relatively unsuccessful commercially for a number of reasons. Some aesthetically unattractive designs have had a negative affect on the motorcycling public’s perception.
Technically, hub-center steering systems Achilles heal is the lack of front end feel. This is mainly due to the extra elements between the tire contact patch and the handlebars. If you think about a standard fork, there is a very direct connection to the rider’s hands, which gives good tire contact patch feedback.
Hub-center steering bikes however have extra parts or elements each with a certain amount of friction and movement which reduces the sensitivity and feel to the tire contact patch.
However, recently manufacturers such as Bimota and Vyrus have been creating some very cool high spec bikes. There is an opportunity with continual development and modern technology we may see resurgence in hub-centre steering designed motorcycles.
Photos: motoDNA & Four oh Four
Mark McVeigh is a former international motorcycle road racer and MotoGP engineer who now works as a moto-journalist and development rider. He currently is also the Director of Coaching at the motoDNA Motorcycle Academy. Read more of Mark’s work on the motoDNA blog, and follow motoDNA on Twitter and Facebook.
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