A Niner Sir 9 is the most versatile 29er I've ever owned. It has an eccentric bottom bracket and horizontal dropouts so you can ride it single speed, fixed gear, IGH or derailleurs. Built with double-butted Reynolds 853. I have the small size since I'm 5'7" and the co-founder of Niner Bikes is only 5'6". This should be the LAST MTB you'll EVER want to buy into the future!