Then, slide bearing spacer (00106) so it touches the rim bearing and secure it with o-ring. Gently expand the o-ring to put it on the sleeve. Slide the wheel mount (00042) on the sleeve (mind the side). Gently push the mount in the spacer direction so it lightly presses the o-ring. Keeping the pressure, tighten the mount screws. First, tighten lightly the one closest to the rim, next firmly tighten the second, and then re-tighten the first one.