14 Mar 2010

The Viktor


The Viktor tricycle. The Formula 1 of invalid tricycles? Art and clever design in one very useful package. This one has an electric motor in the rear hub.

The Viktor is an example of a highly sophisticated, invalid tadpole trike with low step through height. (and two wheels forward) It is always eye-catching on the road in any colour. It has Ackerman steering, tilting on turns and drum brakes. The Victor (and smaller Victoria) are possibly the most popular invalid trikes on the roads of Denmark. Though they are far from cheap!  Being unisex the different models refer more to the frame size rather than being specifically aimed at the male or female client.

Through adjustable linkage rods, levers and bellcranks the trike is made to lean gently inwards on corners. Which must aid stability. This one enjoys a rear electric motor hub drive with the battery pack fitted neatly behind the saddle. It is referred to as a "helper motor" in the sales text so is not really intended as an all-electric, three-wheel scooter. The motor probably provides useful assistance on uphill sections with the help of some gentle pedalling.

One slight oddity is that the kingpins lean backwards as well as outwards. This would suggest negative trail. A line dropped vertically from the hub centre would meet the ground in front of a line through the axis of the kingpin. This is the reverse of the normal steering geometry.

Sadly this beautiful machine is just too heavy at 30kg (60lbs) to fit with racing handlebars. Then blast around the back lanes as if it were a sports trike. Or I'd probably own one myself by now. I'd still love to have a go on one just for the sheer fun of it and to see how it handles at speed with a reasonably fit rider aboard.

I find the whole design of the Victor series particularly elegant in comparison with the average invalid trike. The designer must be someone who highly respects his customers (and himself) as well as showing remarkable skill and ingenuity. An ultra-lightweight aluminium racing model would be great fun but probably have a very small market. Perhaps a light version it is just what is needed to match the seemingly arbitrary rules being suggested for disabled racing cyclists?  I just love the look of the Victor. All of its wonderful curves and the many clever design features. It would be really difficult to try and make it better. This is great engineering and intelligent design in my humble opinion.

Here's a closer look at the steering rods and tilting linkages and control rods. The angled tilting rods are covered in plastic coils which also contain the front brake cables. So the rods and their purpose are rather difficult to identify at first sight. As the hubs are turned by the handlebars the linkages tilt the trike slightly. This brings the centre of gravity of the rider slightly inboard to avoid the trike tipping. This also avoids the rider having to deliberately lean inwards. Thus making for a very relaxed ride. If you look closely there is a hinged bell-crank at the top of the tilt push rods. (just below the basket) The steering assembly has secondary cranks just above the king pin axles which give the necessary push to the linkages. All of the steering rods use adjustable spherical track rod ends for long life and low friction at all likely angles. This is real attention to detail and incredibly sophisticated for a machine aimed directly at an invalid or elderly market. The axle pivot is in the centre on strong brackets welded to the swooping main tube. This machine is a true masterpiece of design compared with the average invalid trike.

I could really see a stripped down version of this trike (in a much lighter form) taking over duties as the racing trike of choice for international, handicapped competition.  Recumbent trikes are too near the ground for most riders to enter comfortably and require very strong neck muscles. Delta upright trikes are inherently unstable and the wheels impossible to see from the riding position. This has led to some badly thought out accessories like rear crash bars. The Viktor frame would have to be reproduced in aluminium and probably disk brakes fitted. The Roman Road Newton is an obvious competitor but has a higher step through height and slightly unwieldy front wheels. If it had (say) 24" or even 20" front wheels it would appear much better balanced. (IMO) This would of course require that suitable racing tyres and rims were available in such sizes.  (Just thinking aloud here)

Invalid tricycles aim for stability, safety and ease of use almost regardless of weight. In fact many invalid trikes are (arguably) unnecessarily heavy considering their elderly, or infirm owners. What they do though is provide much greater mobility for a weakened body. The owner may no longer manage a brisk walk to the ever-more-distant supermarket but can still manage a steady bicycle ride. Particularly if the ride is on the flat or only slightly inclined. Aided by the vital third wheel for balance the trike rider can stop at any time they care to. Without having to put a foot down or even dismount. Nor do they have to push off and remount a wobbly bicycle, at critically low speed, in heavy traffic, in the rough and littered gutter of today's badly maintained roads. Even though it might be heavier than a bike the trike offers huge advantages over a normal bike for  the elderly and infirm. For those with balance problems the trike is indispensable to local mobility.

Most invalid trikes have fitted carriers or baskets to carry shopping and usually somewhere to safely stow a vital walking stick. Relatively low speeds tend to be the norm since the rider is not usually very fit. A low saddle, low speeds and low gears help to ease problems with balance for the rider even on sharper corners.

Conversely a sports trike requires great athleticism in its rider to cope with sharp corners taken at much higher speeds. The trike is not an unconditionally stable device except when parked on a dead-flat surface. It certainly won't fall over when standing still but may need a parking brake to stop it rolling away! Many invalid trikes have such a device incorporated into the brake lever(s). Or use the security (wheel) lock for the same purpose in a slightly cruder way.

This is a the rear end of another yellow Viktor but this time without an electric motor hub. Don't you find the curve of the chainstays inspired as they protect the chainwheel from contact with the feet of the rider? The curves of the stays balance the strong curve of the main frame tube to perfection. Providing visual movement in the clever design of the frameset. Far beyond boring old, straight stays plucked straight from the 19th century.

An electrically assisted Viktor providing essential transport in the depths and darkness of a Danish winter.