diff --git a/STM32/CM7/Core/Inc/macros.h b/STM32/CM7/Core/Inc/macros.h
index 88518e7..d76b5da 100644
--- a/STM32/CM7/Core/Inc/macros.h
+++ b/STM32/CM7/Core/Inc/macros.h
@@ -2,7 +2,7 @@
 // Copyright (C) 2026 Pierre Barbier <pierrebarbier741@gmail.com>
 // Copyright (C) 2026 Association Exergie <association.exergie@gmail.com>
 // SPDX-License-Identifier: GPL-3.0-or-later
-
+#include "global_state.h"
 #ifdef DEBUG
 #include "SEGGER_RTT.h"
 #define DEBUG_LOG(fmt, ...) SEGGER_RTT_printf(0, fmt "\n", ##__VA_ARGS__)
@@ -13,3 +13,5 @@
 #endif
 #define CRANK(num) ringBufferRead(&state_g.crank_RB, num)
 #define CAM(num) ringBufferRead(&state_g.cam_RB, num)
+#define D1A CRANK(0)-CRANK(1)
+#define D1B CRANK(1)-CRANK(2)
diff --git a/STM32/CM7/Core/Src/tasks/crank.c b/STM32/CM7/Core/Src/tasks/crank.c
index 1ed9823..8d74158 100644
--- a/STM32/CM7/Core/Src/tasks/crank.c
+++ b/STM32/CM7/Core/Src/tasks/crank.c
@@ -4,6 +4,7 @@
 // SPDX-License-Identifier: GPL-3.0-or-later
 
 #include "cmsis_os2.h"
+#include "global_state.h"
 #include "macros.h"
 #include "main.h"
 #include "ring_buffer.h"
@@ -16,6 +17,12 @@ void crankHandler(void *argument) {
     DEBUG_LOG("Crank pulse detected at: %lu\n\r",
               ringBufferRead(&state_g.crank_RB, 0));
     // FILTER
+    float delta_percentage = ((float)(D1A - D1B)) / D1B;
+    if ( delta_percentage> 0.4||delta_percentage < -0.4) {
+        state_g.sync_state = SYNC_NOT_OK;
+        state_g.crank_state = CYCLE_UNKNOWN;
+        continue;
+    }
     // INCREMENT SWITCH
     switch (state_g.crank_state) {
     case CYCLE_COMPRESSION: {