diff --git a/src/diskcontroller.cpp b/src/diskcontroller.cpp
index 95101a3..9e765ba 100644
--- a/src/diskcontroller.cpp
+++ b/src/diskcontroller.cpp
@@ -85,8 +85,7 @@ unsigned char DiskController::io(const unsigned short addr, const unsigned char
  * (When the motor is on, that is.)
  */
 void DiskController::tick() {
-    this->drive1.tick();
-    this->drive2.tick();
+    this->currentDrive->tick();
 
     if (this->ioStepped) { // if we already ran it, above in io(), skip here
         this->ioStepped = false;
@@ -105,21 +104,24 @@ void DiskController::tick() {
      * then inject the next bit and subtract the optimal bit timing from your bit timing clock.
      * That will give you 125ns resolution on your bits being fed to the sequencer.
      */
-    rotateCurrentDisk();
 
     // run two LSS cycles = 2MHz
+
+    rotateCurrentDisk();
     stepLss();
+
     // pulse lasts only 500 nanoseconds (1 LSS clock cycle), so clear it now:
     this->currentDrive->clearPulse();
 
+    rotateCurrentDisk();
     stepLss();
 }
 
 void DiskController::rotateCurrentDisk() {
-    ++this->t;
-    if (4 <= this->t) { // 4us interval between bits
+    this->t += 1.0f;
+    if (this->currentDrive->optimal_timing()/4.0f <= this->t) { // 4us interval between bits
         this->currentDrive->rotateDiskOneBit(); // (will also generate a read-pulse when it reads a 1-bit)
-        this->t = 0;
+        this->t -= this->currentDrive->optimal_timing()/4.0f;
     }
 }
 
diff --git a/src/diskcontroller.h b/src/diskcontroller.h
index ad37fda..bc321bd 100644
--- a/src/diskcontroller.h
+++ b/src/diskcontroller.h
@@ -55,7 +55,7 @@ private:
     // On the real Apple the read pulse goes thru this LS174 too, but we don't emulate that here.
 
     std::uint8_t prev_seq; // remember previous seq, to determine if A7 changes (indicating write a 1 bit)
-    std::uint8_t t; // used to keep track of 4 MPU cycles
+    double t; // used to keep track of optimal bit timing interval
 
     // TODO for a rev. 0 motherboard, the disk controller will auto reset the CPU (see UA2, 9-13)
 
diff --git a/src/drive.cpp b/src/drive.cpp
index 8270a38..5e4af15 100644
--- a/src/drive.cpp
+++ b/src/drive.cpp
@@ -47,6 +47,10 @@ bool Disk2Drive::isModified() const {
     return this->disk.isModified();
 }
 
+int Disk2Drive::optimal_timing() const {
+    return this->disk.optimal_timing();
+}
+
 int Disk2Drive::position() const {
     return this->head.position();
 }
diff --git a/src/drive.h b/src/drive.h
index 95f0712..4c1f5fd 100644
--- a/src/drive.h
+++ b/src/drive.h
@@ -53,6 +53,7 @@ public:
     void saveDisk();
     bool isWriteProtected() const;
     bool isModified() const;
+    int optimal_timing() const;
     int position() const;
     void tick();
     void set_phase(int i_phase_0_to_3, bool on);
diff --git a/src/wozfile.h b/src/wozfile.h
index d475e8c..07bfb04 100644
--- a/src/wozfile.h
+++ b/src/wozfile.h
@@ -134,6 +134,13 @@ public:
     bool getBit(std::uint8_t currentQuarterTrack);
     void setBit(std::uint8_t currentQuarterTrack, bool on);
     void rawSet();
+
+    int optimal_timing() const {
+        if (this->loaded) {
+            return this->timing;
+        }
+        return 32;
+    }
 };
 
 #endif // WOZFILE_H