(Undated) -- Keep your eyes peeled for motorcycle riders. The Minnesota Department of Public Safety says that is even more crucial as they expect more cycles on Minnesota roads headed to the annual Sturgis rally in South Dakota starting Friday. Officials say the largest expected increase in volume will be on the I-90 corridor. According to D-P-S, failure to yield to motorcycles is the largest single factor contributing to motorcycle fatalities in the state. So far this year 33 riders have been killed on Minnesota roads, eight more than this time last year.