I'm on a 51 cm Trek 2100. My LBS owner told me I didn't need the WSD because my arms are fairly long and I believed her. (They didn't have any 2100s in my size in stock, WSD or no, so it wasn't like she was trying to unload inventory.) I feel really good on the bike, but much better in the drops than on the hoods. I have little hands, though, so I could probably use something to help me reach the brakes a little better.

I'm 62.5 inches tall.