Drive
For several reasons like weight, vibration by too excessive chain length, etc. the drive in the new model should have an effect on the front wheel.
This in addition made it possible at first to realize the landing gear behind and under the seat.
To allow the front wheel a certain angle of turn and to reach the necessary transmission the chain had to divert above the front wheel to an intermediate gearbox.
By suitable positioning of this gearbox I was able to eliminate the influence of drive forces to the steering.
So eventually I had the following drive variations to choose from:
1. 9speed hub , 3speed with "rear derailleur" in the intermediate gearbox (upper chain), single chainring in front
2. 9speed hub , 3speed with "front derailleur" in the intermediate gearbox (lower chain), single chainring in front
3. 9speed hub , no derailleur just transmission in the intermediate gearbox, triple chainring in front
4. only a single sprocket on the hub, 8speed with "rear derailleur" in the intermediate gearbox (upper chain), triple chainring in front
5. 14-speed-Rohloff-hub , no derailleur just transmission in the intermediate gearbox, single chainring in front.
Here some details to the Rohloff-drive
Finally No.4 was out of the question because of required a width of more than 8 cm at the diversion gearbox.
No. 1 also would have been too wide by the derailleur in the gearbox and the chainlines were not favourable.
At No. 2 problems had appeared with the steering turn caused by the only shifting in the lower chain, i.e. in certain gears the chain and the tyre had come in contact with each other already at a slight steering turn.
Therefore at long last only No. 3 and 5 were in competition, i.e. the use of an intermediate gearbox without additional shifting possibilities but only with the function of diversion and transmission had already been fixed.
So the opponents were the 14-speed-hub and the 9speed-hub in combination with a triple chainring at the cranks.
