In the past, I would simply wrap the innertube around the stay, and zip-tie it on. While this method is quick and effective, it's not pretty. And let's face it, your bike deserves to look good.
Let's make a better-looking chainstay protector by sewing on the innertube with a baseball stitch!
Step 1: Tools and Materials
* Mountain bike inntertube
* Dental floss or upholstery thread
* Large sewing needle
* Masking tape
* Silver gel-pen, paint pen, or makeup pencil
Depending on the diameter of your chainstay, you may be able to get away with a road bike innertube, but chances are you'll need a mountain bike tube. If you're really lucky, you might find a latex innertube in fun colors! These are the best, and they're extra stretchy so you can safely ignore the road bike remarks from earlier.
You will need to mark on the tube. Silver gel pen really is the best, but a paint pen or makeup pencil will work.
Step 2: Cut the Innertube to Length
Next, cut the tube along the "long way" to open it up. It's important that this cut be straight, so follow one of the molding ridges.
Finally, wash the talc out of the inside. Gross.
Step 3: Cut Innertube to Tightly Wrap Around the Stay
Begin by running one edge of the tube along the middle of the chainstay, and taping it in place with masking tape. Run your fingernail along the tape to get a hard, crisp line along the edge of the tube
Next, wrap the rest of the tube around the stay tightly. Because you ran your fingernail down the tape earlier, you should be able to feel exactly where the tubes overlap. Take a gel-pen, paint pen, or makeup pencil and mark the overlap.
Remove the innertube from the stay, and discard the tape. Cut along the line you've marked. To get a snug fit, cut slightly inside the line; the innertube will stretch, although not quite as much as you think.
Step 4: Mark the Stitch Holes
Place a ruler along one edge of the innertube, and using your gel-pen, make a mark every 1/4" (5mm). If that seems like way too many holes to you, remember that the more stitches you have, the less noticeable any given goof-up is!
You don't need to bother marking the other edge. You can easily eyeball the proper placement of those stitches using the marks from the first edge.
Step 5: Baseball Stitch 101
First, double the thread on the needle.
Begin the baseball stitch by making one straight overthrow stitch, and knotting underneath.
Pierce the fabric from the bottom, and pull the needle up through the fabric towards you. Then bring the needle into the seam, under the next piece of fabric, pierce the fabric from the bottom, pull the needle up towards you, and repeat. Continue sewing until you reach the end, and finish with another overthrow stitch.
Refer to the diagram, and it will make tremendously more sense. The dark-grey line is the thread that's hidden under the fabric.
Photos of the sewing process are on the next page.
Step 6: Sew the Innertube
You want a nice thick thread for this sewing job. You can use upholstery thread if you have it; if not, dentil floss works just as well. A typical mountain bike chainstay requires 5-6 feet of thread. Take a wide arm-span of thread, and let's begin.
Thread the needle, and tie the two ends together so the thread is doubled up.
Wrap the innertube around the stay, and sew the overthrow stitch. Catch the knot at the end of the thread with the needle and pull everything tight. If you are right-handed, it will be easier to start at the axle side of the stay, if you're left handed, start at the crank side.
The first few stitches are the most difficult. Use the marks you made earlier to space your stitches evenly. Pinch the tube together with the fingers of your non-sewing hand as you go, and remember to always push the needle up through the underside of the tube. The pointy part of the needle should always be traveling away from your bike's paintjob!
Snug up each stitch by gently tugging the thread while pinching the tube together with the fingers of your non-sewing hand. Most of the work should be done by pinching with your fingers, not by yanking the thread. Yank too hard and you'll rip the tube!
Once you've sewn the first quarter of the chainstay, things will go much more smoothly. At this point, instead of snugging each stitch, you may find it faster to loosely sew several stitches in a row, then snug them all at once. Use the marks you made on the tube to keep your stitches spaced evenly.
Step 7: Finish It Up
Because the chainstay is tapered, you may want to slide the finished protector towards the cranks to snug everything up.