To tighten the handlebars:
1 Loosen the collar clamp. With a side to side twisting motion, push and twist to slide the stem onto the fork until it bottoms out on the headset locknut.
2 With the front wheel pointed straight ahead and the handlebars square to the front wheel, tighten both bolts on the clamp with a 5 mm Allen wrench. Tighten securely.