I've used MikroTik hardware in the past to build wifi hotspots for customers. It's pretty easy to use, very friendly command line. You want something like this in an enclosure something like this. They're reasonably robust, and once configured properly, will do what you want (and a whole lot more should you want to change the setup in future) for a good long time.

Find a Xexun TK-102 on ebay, they will report back their position via the mobile network (you supply a SIM card, and can send it a request for the current position, it will text you back). You can get large extended battery packs too, or you could wire it into the bike's power. They work well enough for us to track drivers at work. Just make sure you get a genuine Xexun one, the others are less reliable and tend to lie about their position, in my case being offset by about 4 miles. There are separate car sized ones, but I have not used them.

I have been using one of these http://www.kabseating.com/office/product.asp?product=81 for the last ten years. Properly adjusted, they are fantastic. Expensive but I can't recommend them enough! I have no doubt that this has prevented my existing neck and back problems from degenerating further.