Only now I am building a mtb with an internal geared hub. For several years I abuse internal gear hubs and I am still to find the sort of bicycle riding style they will not fit. German manufacturers are building DH and freeride bicycles with internal gear hubs and I am wondering why ?! An internal gear hub can be shifted when ever the rider wants, even in effort and I dought the strongest of the riders during the hardest of effort will damage such hubs. Try a Nexus 8 with a 22 teeth cog and an ordinary crank with 44, 32, 22 chain rings and you will see your bicycle climbing walls! If you do not believe me, read Sheldon Brown's articles on internal geared hubs or send him an E.mail on the issue and then make your conclusions.