diff --git a/lib/Speedometer/speedometer.h b/lib/Speedometer/speedometer.h
index 55f05eb..04abc50 100644
--- a/lib/Speedometer/speedometer.h
+++ b/lib/Speedometer/speedometer.h
@@ -23,14 +23,13 @@
  * 
  */
 #define BUFSIZE 5
-#define CONVERSION_FACTOR
+#define CONVERSION_FACTOR 100
 
 /**
  * @brief Default value for min Millisseconds between each loop
  * @see setDelay(uint8_t val)
  */
 #define DELAY_SPEEDOMETER 30
-#define PI 3.141592
 
 /**
  * @brief A class which use a encoder to calc the speed