diff --git a/src/ANT.cpp b/src/ANT.cpp
index 5dcf36ef1..8d03cb403 100644
--- a/src/ANT.cpp
+++ b/src/ANT.cpp
@@ -82,7 +82,7 @@ const ant_sensor_type_t ANT::ant_sensor_types[] = {
 // thread and is part of the GC architecture NOT related to the
 // hardware controller.
 //
-ANT::ANT(QObject *parent, DeviceConfiguration *devConf) : QThread(parent)
+ANT::ANT(QObject *parent, DeviceConfiguration *devConf) : QThread(parent), devConf(devConf)
 {
     // device status and settings
     Status=0;
@@ -152,6 +152,15 @@ double ANT::channelValue(int channel)
     return antChannel[channel]->channelValue();
 }
 
+void ANT::setWheelRpm(float x) {
+    telemetry.setWheelRpm(x);
+
+    // devConf will be NULL if we are are running the add device wizard
+    // we can default to the global setting
+    if (devConf) telemetry.setSpeed(x * (devConf->wheelSize/1000) * 60 / 1000);
+    else telemetry.setSpeed(x * (appsettings->value(NULL, GC_WHEELSIZE, 2100).toInt()/1000) * 60 / 1000);
+}
+
 /*======================================================================
  * Main thread functions; start, stop etc
  *====================================================================*/
diff --git a/src/ANT.h b/src/ANT.h
index 4b44786e7..57fd1be6f 100644
--- a/src/ANT.h
+++ b/src/ANT.h
@@ -334,10 +334,7 @@ public:
     void setCadence(float x) {
         telemetry.setCadence(x);
     }
-    void setWheelRpm(float x) {
-        telemetry.setWheelRpm(x);
-        telemetry.setSpeed(x * (appsettings->value(NULL, GC_WHEELSIZE, 2100).toInt()/1000) * 60 / 1000);
-    }
+    void setWheelRpm(float x);
     void setWatts(float x) {
         telemetry.setWatts(x);
     }
@@ -356,6 +353,7 @@ private:
     int channels;  // how many 4 or 8 ? depends upon the USB stick...
 
     // access to device file
+    DeviceConfiguration *devConf;
     QString deviceFilename;
     int baud;
 #ifdef WIN32
diff --git a/src/DeviceConfiguration.cpp b/src/DeviceConfiguration.cpp
index 3fe33a793..d840b8de2 100644
--- a/src/DeviceConfiguration.cpp
+++ b/src/DeviceConfiguration.cpp
@@ -89,6 +89,7 @@ DeviceConfigurations::readConfig()
             configStr = QString("%1%2").arg(GC_DEV_WHEEL).arg(i+1);
             configVal = appsettings->value(NULL, configStr);
             Entry.wheelSize = configVal.toInt();
+            if (Entry.wheelSize == 0) Entry.wheelSize = 2100; // default to 700C
 
             configStr = QString("%1%2").arg(GC_DEV_PROF).arg(i+1);
             configVal = appsettings->value(NULL, configStr);