Yup, if you have a damaged rim, go to an 18"...more tires to choose from. Short of a damaged rim, I wouldn't spend the money. I, too, have heard of the 19" flat prone problem. However, in all the races I have entered, both Nationals and regionals, Desert to ISDE qualifiers, and all the rocks and logs I have had to endure, I have only had one flat, and that was on the front. I was just beginning to race the National series, and got a flat front flat 10 miles into the event. Raced the next 90 miles on a front flat. Ironically, at every check I was informed I had a front flat. Like I didn't know, Duh.
As a note, I have never had a rear flat during an event. I guess the key to my success is the heavy duty Fly tubes, and I use two tubes each year, front and rear. I give my old ones away at races when someone has a flat and needs a tube. The long and short of this is that I have not had problems with flats with a 19" rim, and I ride pretty fast and hard, and ride a lot of miles, so don't believe the "more prone to flat" story.
As for the rear hub, if the rim and spokes are good, just swap out the hub with a Talon hub. Super strong, and you should be able to get one for about $300.
Good Luck.
Rick
