Operator’s Manual 125 MAX DD2 evo
Page 57/70
Edition 09/2016
This is a suggestion. The optimum choice can only be found with the exact knowledge of the race
track.
To approach and optimize the reduction gear ratio, the following charts should be helpful.
The optimization procedure regarding the reduction gear ratio for a new race track is explained
step-by-step in the following example:
Æ
Start with the standard gear ratio (35/62, equivalent to 12/90 in 1
st
gear and 14/79 in
2
nd
gear).
Based on the following criteria, you must decide, whether a shorter or longer gear ratio is
necessary.
Does the engine reach 12.500 rpm in 2
nd
gear at the end of the longest straight?
IF YES:
Æ
Choose the next longer gear ratio (36/61 equivalent to 12/87 in 1
st
gear and 14/76
in 2
nd
gear).
IF NO:
Æ
Choose the next shorter gear ratio (34/63 equivalent to 11/87 in 1
st
gear and 14/83
in 2
nd
gear).
If these gear ratios are still not sufficient, try the next shorter or next longer gear ratio.
¿
Note:
When using short gear ratios, it may happen that the response behaviour of the
engine in 1
st
gear is aggressive and the vehicle handling becomes difficult. For a
good lap time, often a longer gear ratio is helpful to achieve reasonable performance
behaviour.
¿
Note:
To help with the choice of adequate gear ratios, the two charts below illustrate the
traditional gear ratios and the top speeds in [kmh] that can be reached in the
respective gear at an engine speed of 12.500 rpm.
Gear ratio 1st gear
Number of teeth on
primary drive gear
1. gear overall
gear ratio
Traditional gear
ratio
(in sprocket sizes)
theoretical max. speed
(in km/h / mile/h)
(at 12.500 r.p.m. and wheel
diameter 870 mm
/ 34,25 in.)
32
65
8,65
10 to 87
75 / 47
33
64
8,26
11 to 91
79 / 49
34
63
7,89
11 to 87
83 / 52
35
62
7,55
12 to 90
86 / 53
36
61
7,22
12 to 87
90 / 56
37
60
6,91
12 to 83
94 / 58
38
59
6,61
12 to 80
99 / 62
4,26
gear ratio of 1st gear (cannot be changed)
Number of teeth on
secondary drive gear
