I've been looking at new bikes to replace my old Trek 930. I've looked at Specialized Tri Cross, a Salsa Vaya and now a Giant 29er. While I realize that it's mainly the motor that is slow on the 930 I want something with more speed. Is the 29er faster than a mountain bike? Is it just a matter of putting on road tires? Are they fast enough to get my speed fix? Thanks for the help.