How to Install BMX Handlebars

To install handlebars on a BMX, follow these simple steps:

Unscrew the faceplate of your stem with an Allen wrench.
Place the handlebar in the stem, making sure the knurled section of the handlebar is dead center in the stem.
Assemble the stem by clamping it around the handlebars. Use your fingers to tighten the bolts at first.
Tighten each bolt with an Allen wrench. Be sure to tighten the bolts gradually in a cross pattern to ensure equal tightness on all four bolts.
Before fully tightening the bolts, check the gap between the stem and the stem faceplate. The gap should be the same across the stem. If it is, tighten the bolts fully, following the cross pattern.

Now your handlebars are installed.