Well, I've watched many vids on what people have added to "trick" our their Rads. One guy did have an after market rail that he bought for about $99. He even admitted that was pricey and I wouldn't pay that. We have 3 bikes, 2 touring models and also a trek tandem. They all have the Topeak system. Since we are going to sell the tandem, ( a nice bike but my wife was always a bit fearful on it) I had a least one surplus rack. Rather than take off the Rad rack I bought, I just cut off the legs on the Topeak rack and it fits fine and the pack slides right on.