Wrong computation in ifelse on factors

I have a dataframe called g1. It has 3 columns that are factors: max_num, max_res and g1$bdest. I have a number N = 8. I would like to create a new column with name g1$WMA. For each row: in case g1$max_num > N/2 I would like g1$WMA to get the value g1$max_res otherwise - g1$bdest. I used the following command, however I get a wrong computation:

g1$WMA = ifelse ( (( as.numeric(as.character(g1$max_num) ) )> (N/2)), g1$max_res, g1$bdest) 

How can I correct it?