I bought the tapered bolts for my F6B when I put the Ultimate Seat on my bike. Even with the tapered bolts I still had a time with one of the holes. Seems that either the threads are a bit tight or there may be some frame paint or coating in the threads. On the wife's F6B I did not use the tapered bolts, chasing the threads & using a round phillips screwdriver to line up the bolts worked out real well for me.