I made this a couple of years ago, well before I knew about Instructables. I think it's a perfect topic: making something extremely useful from recycled parts / pieces. This is the kind of thing I've seen on BMX bikes.
Have you ever got cable pinch on your mountain bike, from where it sits in the bike rack on your car? This top tube protector will put an end to that!
Just so we're on the same page, I've added the anatomy of a bike in the picture.

Step 1: Ingredients

- an 18 inch long swatch of fabric that you won't mind seeing on your bike; this is the outer fabric.
- An 18 inch long matching piece of cordura nylon, or other durable fabric. This is the inner fabric, and should be able to take a lot of wear.
- Fabric widths may differ from bike to bike, due to length and circumfrence of the top tube.
- 1 inch Velcro hook and pile; as much Velcro length as fabric length.
- A piece of closed cell foam, like the stuff camping sleeping pads are made out of. I used a slice of my RidgeRest foam mattress.
- Measuring tape
- Scissors
- A sewing machine, although it can be hand stitched.

Step 2: Ingredients: Inner Fabric and Velcro

Black cordura inner fabric.

Step 3: Ingredients: Closed Cell Foam

This piece of foam will fit into the sheath made out of the inner / outer fabric.

Step 4: Ingredients: Tools

A handy sewer with a sewing machine, scissors and the all important measuring device.

Step 5: Measure Thrice Cut Once

If you're me, you go like hell, excited and willy nilly.
Lucky for me that the missus got a hold of this, measured properly and has the sewing skills.
Cut your fabrics and foam.

Step 6: Make a Model

As with a lot of projects, I (the missus) pinned the whole shebang together first, as a big envelope, and made sure the foam would fit.

Step 7: Vecro-ize

I'm sure that after a fair amount of adjusting and pinning, my missus sewed the Velcro on in such a way that it is concealed from view.
Although I'm lucky enough to have a sewing missus, this project can be done by hand, if you've the patience. A quick and dirty solutuion is to just zap-strap some foam to your top tube.

Step 8: Velcro Picture

Here's a good view of the finished product, not mounted, detailing the Velcro. Boy, am I lucky to have married my missus.

Step 9: Mounted View 1

Here it is, mounted on your UAB (Urban Assault Bike). This fits over the cable housings, doesn't interfere with gearing or braking, and is better loose, not too tight. So far, no more cable bite, and it's easily removable.

Step 10: Armoured Top Tube

Another view of the mounted protector. As a final flash of brilliance, envision 2 strategically sewn Velcro loops on the top of the protector, to hold your bike pump, as you pedal your butt around town.
Cool, eh?