The ESP derailleur.
Derailleurs for mountain bikes are derived from racederailleurs.
Because the capacity of a race derailleur is less (12-27) than that of a mountain bike (11-34), we can apply a similar type of bicycle derailleur, but with a longer cage.
The geometry of the derailleur is thus not adjusted.
The problem that then arises is that if you go to a larger sprocket the distance top roller – sprocket becomes smaller.
This may cause switching problems.
These problems are solved at an ESP derailleur with the following modifications.
- The ratio of derailleur – shifter.
Many derailleurs have a ratio of 1 – 2.
This means that if 5 mm cable in the shifter is moved then the rear derailleur will move 10 mm.
In an ESP derailleur, the ratio is 1 to 1.
This is to say, if there is 5 mm cable moved in the shifter, the rear derailleur also moves 5 mm.
This 1 : 1 ratio halves the problems of a badly adjusted derailleur and problems with shift cables.
At the 1 : 1 system the cable tension is therefore reduced by half.
This has the result that the friction in the cable and other conductors as well is the half.
This has been able due to the operating lever that is twice as long on a 1: 1 system .
Because the ESP derailleur and shifter have a 1: 1 ratio, they are not interchangeable with 1 : 2 systems.
- By adjusting the geometry of the derailleur. The angle of the parallelogram at an ESP derailleur is 48%.
In other derailleurs, this angle is 42%.
- Placement upper derailleur sprocket.
By adjusting the angle and the placement of the top roller the distance between the top roller and the chain wheel is kept the same in all gears.
The axis of the roller at an ESP derailleur is positioned in the pivot of the cage.
This gives you no distance change when switching to another gear.
In the other derailleurs this distance changes, because the axis of the roller is not at the pivot point of the top roller and the chain wheel.
- Not spring in the pivot point of the derailleur frame
To keep the distance of the top roller and the chain wheel equal, the spring force of the spring in the pivot point and the spring in the cage must be equilibrium with the position of the top roller.
It is impossible to get the spring in the pivot point of the cage tighter.
Therefore the spring at the pivot of the derailleur to the frame has been abolished .
The switching operation is improved by the addition of an additional spring in the hinge point of the parallelogram.
If there is switched with a conventional derailleur to a larger chain wheel the spring in the parallelogram is at a certain point over its maximum spring force.
By placing an additional spring, the derailleur responds more directly when switching back from the largest sprocket to the smallest sprocket. Figure 26 shows this effect again.
The use of an additional spring gives the derailleur a different spring characteristic. Figure 27 shows the differences.