Changing a rim
step 1.
Fasten the new rim with the old rim using tape, make sure that the valve holes are parallel to each other. (See pic.)
Step 2.
Move the spokes one after one from the old rim to the new one, start with one off the spokes that is nearest the valve hole and closest to the new rim (See pic.) Do not tighten the nipples yet, just screw them on a little bit, check all spokes and nipples so there not rounded or worn out, replace if they are. Grease all nipples before you screw them on (that makes it easier to adjust and replace the rim in the future) when you are finished whit all spokes on one side, the hub should bee near the center of both rims.
When one side is finished continue whit the other side, spoke after spoke, until all spokes are on the new rim. Now, take away the tape and hang the old rim on the wall, ore throw it on the nearest guy you hate (don´t blame me if he gets hurt).
Step 3.
Now screw the nipple in until the thread on the spoke is invisible (start whit the one nearest the valve hole),it´s very important that the spokes and nipples are equally long and that you don´t screw to much ore to little, otherwise the hub won´t be in the center of the rim. Take your time to get it perfect, it´s worth it!.
Step 4.
Now it´s time to tighten the spokes. Again, start at the valve hole and screw 2 ore 3 turns depending on how loose the spokes are,it´s very important that you screw equal turns on every spoke until you have reach the last one, next round, just screw 1 turn on each spoke, you may have to do this 3-4 times until the spokes are beginning to "stretch". if the nipples is too tighten after a half round you have to go backwards and unscrew every nipple equally turns that you just did till you reach the valve hole.
Step 5.
Put the wheel in a truing stand ore on your bike (using the brake pads to see if the rim is straight) and do the final adjustment to get your rim perfect!!!!
Tips!
always start at the valve hole and do spoke after spoke, don´t jump back and forth, then your wheel are not going to be straight.
This is going to take some time but don't stress it, you are saving your selves some money that you can du better things with.
If you don't get it straight, leave the wheel to a store, you have still saved some money by putting the new rim on.
I used a 36 spoke rim for this demo, but it´s exactly the same procedure on a 48 spoke rim, it´s even easier with a high wall rim.
After a day of riding, tighten the nipples again and check them after every week or so.