diff --git a/rowers/dataprep.py b/rowers/dataprep.py
index acb1ff77..fa47dec4 100644
--- a/rowers/dataprep.py
+++ b/rowers/dataprep.py
@@ -362,7 +362,10 @@ def save_workout_database(f2,r,dosmooth=True,workouttype='rower',
         velo = 500./pace
                 
         f = row.df['TimeStamp (sec)'].diff().mean()
-        windowsize = 2*(int(10./(f)))+1
+        if f !=0:
+            windowsize = 2*(int(10./(f)))+1
+        else:
+            windowsize = 1
         if not 'originalvelo' in row.df:
 	    row.df['originalvelo'] = velo
 
@@ -1053,7 +1056,10 @@ def dataprep(rowdatadf,id=0,bands=True,barchart=True,otwpower=True,
         rhythm = 0.0*forceratio
         
     f = rowdatadf['TimeStamp (sec)'].diff().mean()
-    windowsize = 2*(int(10./(f)))+1
+    if f != 0:
+        windowsize = 2*(int(10./(f)))+1
+    else:
+        windowsize = 1
     if windowsize <= 3:
 	windowsize = 5