I have a WSD Trek Mamba 29er Mountain bike and DH has the same size in men's. There are some differences but not much. My handlebars are smaller and I think the top tube is sloped differently. Love the WSD design on my Mamba much better than his men's Mamba but not sure what makes the difference.

I'm 5'10" and ride a 56cm Trek Madone but at times it seems too small. It's not WSD though. Seems that size is hard to find. My son has an Allez that's bigger (can't remember size but it's HUGE) and almost fits me better. I think Specialized makes more comfortable frames but I get frustrated with the gearing problems. Their Tarmac was to die for in comfort. I'd almost wished I bought that bike instead of the Madone.

LBS I went to in Lincoln had a WSD Madone that was small and when I asked about the differences, he said the larger WSD sizes are basically the same size as the regular ones. I sat on the WSD (too bad it was too small) and it felt really nice so again there has to be some kind of difference.

If it feels good to ride it regardless of size or WSD, go for it. I wish I could try a WSD 56 Madone to compare to mine, but I'd have to order it on condition I buy it.

Try out different brands as well. A 56 in one company may not be a 56 in another. If a 58 fits better, do it.

I know the guy said there wasn't much of a difference between the larger sizes of bikes, but there is. I take my Madone in for a fitting with this guy on Tuesday. He said some minor changes would really help with comfort once I explained some of the issues.

So yes, tall people can use WSD bikes if needed. They are just harder to find because they aren't in demand. I wouldn't change my WSD Mamba for anything.

Good luck with shopping for your bike. Take your time so you don't get overwhelmed.