The Trek grips have allen head screws on both the inside and outside of the grip. Look carefully and you will see them. If you look underneath, you will also see a gauge on the outside of the grip, so you can match the angles of the left and right grips perfectly, nice touch!! With the allen bolts tightened on the inside and outside of the grip, they should be rock solid, and never twist. The only disadvantage of this 2011 design, is that you can't install bar ends on the factory bars because of their shape. The ends are flattened, and filled with a gel pad to make them round again under the grip. This is done for comfort, but no end bars can be installed. I only have about 30 miles on my new Trek 7.5FX, but I'm enjoying it so far!