48-hole wheels are particularly strong when laced and trued correctly.
Lacing and truing a wheel is one of the more complicated projects in BMX bike maintenance and building; however, if you are a serious rider you will likely have to build a wheel at some point. With the proper tools and some basic knowledge of BMX wheel components, lacing a 48-spoke wheel can be a moderately easy task to perform. Purchase your parts according to the correct dimensions prior to beginning the lacing process; the bike shop should be able to help you choose compatible parts.
1. Lay out your spokes into four groups of 12. Two of these groups will be used for each side of the wheel and installed in a slightly different manner. Check to see if the spoke holes in the rim are offset. Holes that are offset indicates that they are slightly angled. If they are, make sure that when you begin lacing the wheel you thread spokes from the drive-side of the hub–where the freewheel is–to the offset holes in the rims oriented specifically for the drive-side spokes.
2. Insert the first spoke into the hub flange–which is where the hub is extended up from the axle and manufactured with holes for fitting spokes–from the outside and let the spoke lay directly across the hub body to rest above and in between two flange holes on the opposite side. Count nine holes back from the hole directly to the right of the spoke, and insert another spoke into that hole from the outside. Insert these spokes into the rims in the holes on either side of the valve hole in the rim, and screw them in with a nipple which will act as an anchor for holding the spoke in place. The valve hole is where the valve of your tube will eventually be inserted through the rim once the wheel is finished. Only turn the nipples two to three times.
3. Insert spokes into every other hole in the hub flange from the outside and connect them to the rim in a counterclockwise direction. Skip four holes in the rim in between every spoke and attach each of these spokes with nipples. Flip the wheel around and insert spokes into the opposite side of the wheel following the same instructions.
4. Start the external spoke installation by threading one spoke into the hub flange from the inside of the hub. This is where your last two groups of spokes will come into place. Use a four-cross pattern when building 48-hole wheels by crossing the inserted spoke over the outside of the other spokes already in place to its left, and underneath one more before inserting the spoke into a rim hole. Connect the spoke with a nipple.
5. Repeat step 4 for both the remaining 11 spokes on the initial side of the wheel and for the last 12 spokes on the opposite side. After all of the spokes are connected, give each spoke nipple another turn to snug up the wheel slightly, which at this point will likely still feel pretty wobbly and loose.
6. True the wheel by putting it on a wheel stand and seeing where the bends in the wheel are. Tighten the nipples with small adjustments over several nipples rather than turning one nipple too much, which will invariably pull the wheel further out of true. Tighten nipples on the right if the wheel bends to the left, and vice versa.
7. Work slowly as you true the wheel until the wheel is both snug and lacks bends. Once this is accomplished, your wheel is laced and ready for use.