This little project came about from wanting to clock my speed while out biking. I had been going to buy a bike mount for my Garmin 60csx, but all the reviews I read said that it was prone to popping out. To that end, I engineered (in very little time) an extremely secure way to fasten it to my bike while still being able to remove it for hiking, and which is easily modified by anyone for their own GPS.

Also, sorry if the instructions are not quite up to par, this is only my second instructable, and my first one wasn't very complicated to begin with.

Edit: Please feel free to post any comments on how I might improve this instructable or future instructables, I could really use the advice.

Step 1: Materials

This bike mount is fairly simplistic, and requires very few materials. Despite this, its extremely strong. To that end, you will need:
-Bungee Cord (short)
-2-3 Zip ties
-GPS Belt Clip (The one that comes with your GPS, though most belt clips of the same kind will do, as they are the same diameter connector)
-GPS
-Length of foam pipe insulation
-And a knife(or scissors)
-A bike (obvious, but not pictured)

Step 2: Begin!

My bike is a Specialized Mountain Hard Rock Sport. As such, it does not have a typical handlebar mount, but this worked to my advantage. The first thing to start with is to mount the belt clip onto the top of the bike. I mounted mine upside down because it positioned the GPS farther up, and meant I wouldn't hit it with my legs as I pedaled. I did not have two long zip ties, so I had to make do with a long one and two connected short ones. So...
First, attach the GPS to the belt clip, and then place the belt clip on top of the handlebar area. Move it around a bit until you find a position of the GPS that you like. Remember that spot.
I don't really know how to say this well...
Tighten one zip tie below the leaf spring of the belt clip, and another above(see pictures). This will secure the belt clip to the handlebar and keep it from moving up or down. You could also just use epoxy, but I wanted the belt clip to be removable. I would not clip the zip tie ends for now, as you may decide to reposittion the clip.
Don't worry about the big gap between the bottom of the GPS and the handlebar piece. We'll get to that.

Step 3: Foam Time!!!

Now, cut a short piece of the foam insulation. I forgot to photograph myself cutting it, and it would have been hard to with only one hand. You just need the foam piece to be as long as the distance between the part of the GPS that goes into the belt clip, and the bottom of the GPS (just a couple of inches). Cut it once down the side as shown.
Next, slide the foam in between the GPS and the handlebar piece. The foam will cushion the GPS and prevent it from sliding side to side also. Make sure the foam wraps somewhat around the sides of the GPS unit. If not, you made need wider diameter insulation tubing.

Step 4: Wrapping It Up

Finally, just take the short bungee cord and wrap it around the base of the GPS and the handlebar part. Take care that the bungee cord does not push down the buttons. Now, go test out your new bike mount! I took this one out for a ride and it didn't move a fraction. Nonetheless, it might be a good idea to tie your GPs's wrist Lanyard to the handlebars as a backup.

Happy Trails!