I have an older 10speed schwinn worldsport that I use as my backup fixedgear bike and am considering buying some 27" knobby tires like these, to go on my original wheels and use the bike as a singlespeed mtb. Has this been done? Does this kind of conversion have a name? Anyone know of anyone who has done this and if there are things I may be missing that I should look out for? Suggestions?