From reading various reviews it is my understanding that the stock R1150RT seat will fit the R1100RT and that the 1150 seat was redesigned to make it more comfortable, especially reducing the forcing of the rider to slide forward. I'm on the short side, 5'6", so I have my stock seat adjusted in the lowest position, which gets my feet close to flat footed. I have found on-line a R1150RT seat that I could purchase for a reasonable price. Thanks, oldcarman