Derbi GPR >2004 / Aprilia RS >2006 step 420 IGM transmission crown wheel

IGM brand quality sprockets. As in scooters, the gear ratios in geared mopeds are important to get the most out of the engine. A too long gear ratio can lead you to not take advantage of the full power of the engine, and with a too short one the same, normally you have to follow some guidelines to choose them.
The most important thing is to know that the more teeth you have in the sprocket the longer the gear ratio, and the lower the number of teeth the shorter you shorten it.

In the case of the sprocket it is totally different, if it has more teeth it means a shorter development, on the other hand if it has less teeth it means a longer development.

Valid for the following models:

Motorhispania
- 50 RX 05-09
Peugeot
- 50 XR6 02-06
Aprilia
- 50 RS 06-09
- 50 RS 10-13
- 50 RS4 12-16
- 50 RS4 Replica 12-16
- 50 SX 12-16
Derbi
- 50 GPR Racing 04-05
- 50 GPR Racing 06-13
- 50 GPR Nude 04-05
- 50 GPR Nude 06-13
- 50 Senda SM DRD Racing 11-16
- 50 Senda SM DRD Racing Limited 07
- 50 Senda SM DRD Evo 09-10
- 50 Senda SM DRD Evo Ltd. Ed. 10
Gilera
- 50 SMT 11-16

Technical drawing HERE