recumbent with shaft drive
Timo Sairi is finnish designer who has developed and built a recumbent with shaft drive. Here under you can find his comments and few pictures of his bike.
“First of all let me tell you a litlle of my background.
I am an architect and a furniture designer and I have been working with industrially manufactured design furnitures.
Thats why perhaps my interest is always on simplyfying and to clear any design task given.
One year ago I got an invitation to participate on an exhibition dealing with ecological design, here in Finland.
So I decided to build a recumbent bike since I believe bicycles are very ecological indeed.
One thing that is bothering me with recumbents is often quite a complex and technical look of those (maybe also because recumbents are not well known)
So I wanted to do something about this as a designer, just to make them look a little bit more familiar.
To replace the front chain sprockets and to get rid of long chains sounded like an idea worth of thinking and for that goal a logical area to develop was a shaft drive.
My shaft drive system is based on an excisting component that is made for a normal upright bike.
Longer shaft with swivel joints and teleskopic adjustments was needed.
Advantages are obviously:
– maintanance free system
– very silent drive (especially great difference on a bumby roads where usually all kinds of rattles and noices are caused by the loose part of chain drive),
– clean and safe (estethically and practically)
Disadvantages are:
– high price due to need for special components
– some loss of power when compared with a clean, well oiled chain (though not measured yet, I havent noticed any remarkable difference)
– weight, that is about 1.5 kg more than a chain drive, most of it caused by a heavy hud gear unit.
The bike is equipped with shimano disk brakes, shimano 8 speed alfine hub, pantour`s front suspension hub.
The frame is aluminum and the shaft is carbon fibre. I havent yet calculated any exact prices for the bike but basically it has less parts than a normal chain drive.
The next step would be a foldable version since the system has quite a natural potentials for that, additional equipment like bags and mud guards and an invisible rear frame suspension (inside the frame) are under deveploment.
Also, I have plans for a trike, with the same system.”
