Intro: Bicycle Rim Replacement
Make your wheel anew with a fresh new rim. It's easier than building a new wheel and chances are you won't need much else other than a new rim, a few replacement parts and a gob of free time.
While doing my (almost) seasonal wheel truing I found an unwelcome guest: a harsh new crack in my wheel's rim, emerging from the spoke nipple. I drew the weight off of the offending spoke and re-enforced the neighbors: she still needs to get me to and from work for a week. Beside a bent spoke or two, a few worn out spoke nipples, and this new crack my wheel was still in pretty good shape. I found the exact rim for sale online for less than $20 and I proceeded to swap it out. Swapping rims is simpler than building a wheel outright as there is less to determine. This how I did it; and, how you can do it too.
Don't do it if:
The bent spokes I had were pretty minor. If you took a serious fall and a number of your spokes are damaged or if your hub is damaged then it is not worthwhile just replacing the rim; you are probably better off building/buying an entire new wheel.
Let's get started
The wheel I repaired is a rear 700c road wheel, but the principles here apply to the front as well as other styles and sizes. If it is front wheel you are repairing, try to ignore the emphasis on the drive versus non-drive sides, just make sure to switch sides when called for.
Step 1: Tools You'll Need
If you have done any truing you should already have this one. If not, it is a solid investment, but for those who are starving college students you may be able to get by using a...
Flat head screwdriver
I personally found the screwdriver marginally useful for turning the spoke nipples from the outside the rim.
1 junk spoke
If your rim is deep and hallow, like mine, an extra spoke can make placing the spoke nipples a snap.
Infinitely useful during almost all repairs
Metal Marking Pencil
Optional, but I find it useful for marking notes on the wheel as well as determining trueness.
Cassette tool with (socket or monkey) wrench
If your drive-side spokes are all in good shape then you may get by without this.
If you cannot get the cassette off with just a rag, then you will need a chain whip to pull those pesky gears off. One can be fashioned from ten or so extra chain links, a narrow bolt with nut, and something that can serve as handle with a narrow eyelet on the end. (I used a fine file.) Run the bolt through the last link and through the eyelet and tie it pretty with the bolt. This will do the job and save you from buying this over specialized tool.
Step 2: Stuff You'll Need
New identical rim
Ensure that the rim is identical to the one you are to replace. Check that the new rim has the same number of spoke holes.
If your broken rim has the adhesive type of rim tape you will need to buy a replacement roll. If youre on the cheap athletic tape may be a suitable substitute.
At least 5 new spokes
While you're at it, it would be a good time to replace a few of those bent or thrashed spokes on your sorry rim. If you have them, and chances are you will have a handful of bad spokes, buy the same size from your LBS (local bike shop). Be aware that the spoke lengths can differ from side to side.
At least 5 new spoke nipples
Also, you you'll need some replacement spoke nipples. Five should do it, but since you are doing all this labor, why not treat the new rim right and splurge the $3.60 for a shinny full set? Brass is stronger, yet heavier than aluminums.
Masking or Painters' tape
Any non-residue leaving tape will suffice.
Can't have fun without it; you'll only need a drop per spoke.
Step 3: Prep Work (part 1)
Give your wheel a good inspection. Make notes of any spoke nipples that are rounded or odd shaped and any spokes that are bent. Most metal exhibits certain level of springiness: it is able to return to its original position after a force is applied to it. A spoke that is bent out of shape has exceeded this threshold and hence is fatigued. Fatigued or bent spokes are significantly weaker and must be replaced. My spokes are of the fancy bladed variety; they have a unique ability to "cut the wind" and cost $4 a pop. I replaced only what was necessary. If your spokes can be had for cheap, you may consider replacing a third of them to freshen up the wheel a bit.
Step 4: Prep Work (part 2)
If your chain has shifted past the tallest cog into that crevasse between the spokes and the gears you may have damaged the drive side inbound spokes, like me. These will need to be replaced.
Oh, by the way, inbound spokes are those that exit hub's flange from the outside headed toward the middle. Outbound spokes are those that begin between both of the hub's flanges and head outward. Typically inbound spokes are laced underneath the outbound ones.
Step 5: Setup
1. Find a comfortable chair and plan on sitting for awhile. If you haven't already, remove the tire, tube, and rim tape.
2. Place the wheel on your lap, drive side up. Then place the new rim atop the old -- also drive side up.
3. Align the two rims at the valve hole: this is your point of reference. Also ensure the spoke holes of each rim are aligned. For convenience, tape the two rims together with masking tape at the valve hole and the opposite side.
4. Prep the removal of the rim by reducing the tension on all the spokes. A few full turns clockwise should do the trick.
Step 6: Round One
1. Start with the drive side; it should still be on your lap, drive side facing up. Pick an outbound spoke. Use the spoke wrench or attempt to use the screwdriver to remove the spoke nipple from the old rim.
2. Lubricate the spoke threads. A single drop will be more than sufficient. Especially if your bike is outfitted with rim brakes, ensure no lube touches your slick new rim. Protect it with a (non-oily) rag and wipe off any excess lubricant.
3. Bring the free spoke up to the new rim, check that the hole for the spoke is the equivalent hole, attach the spoke nipple and turn it(counter-clockwise) until only two threads are visible above the nipple.
4. The trickiest part of the whole rim replacement for me was placing and keeping the spoke nipple into the new rim. I had some help from a junked spoke: simply put the threaded end of old spoke through the desired hole, loosely thread the nipple, pull the nipple into place, and then remove the ole helper spoke.
Continue until you have done all the outbound spokes on the drive side. That will be every fourth spoke hole.
Step 7: Round Two
You've got a quarter of the wheel on the new rim, the rest is pretty much repetition. Turn the wheel over so that the non-drive side is facing up. Move all the inbound spokes to the new rim. Again, that will be every fourth spoke hole, just like in round one.
Step 8: Round Three
Turn the wheel over again so the drive side is facing up. Now's a great time to replace the spokes damaged by the chain. Fasten the replacement and all the other inbound spokes into drive side of the new rim.
Step 9: Round Four
It's all downhill from here; you guessed it: turn the wheel over another time. Move the remaining spokes from the old rim to the new.
Step 10: Tensioning
I will extend the warning advised to me from the wheel building book I referenced: wear protective eyewear and avoid looking directly down the end of the spoke nipples while tensioning the spokes. There is a slight danger that your newly installed spokes can shoot lose.
Well, well, she's looking pretty good now, but I bet she's as sturdy as a hula hoop. Tighten (counter-clockwise) each drive-side spoke nipple one full rotation. Repeat three times. Switch to the non-drive side and tighten one full rotation. (If you are repairing a front wheel, do a 0.75 to a full turn on both sides, repeating if needed.) If the wheel is leaning mainly to one side additional tension is probably needed on the opposite side. Tension all the spokes of that side one quarter to a half turn. True as normal to complete your new wheel! Finish it off by applying the rim tape before installing the tube and tire.