This would require the development of a battery based on a different technology. As far as I'm aware, nothing is even on the horizon at this point in time. By the time you add a waterproof case that also protects it against shock and all the stuff that it would really take to bring it up to even being able to do what a Garmin does, the cost starts getting really close to what it would be to just buy the Garmin. iBike with power actually costs more than a Garmin 800. You still have the size and the fact that the screen design is inappropriate for cycling use. You would have to purchase maps because although the GPS doesn't need a data signal, the maps do. And once all that's done, it's still too big and heavy.

Bottom line is that if you need a cycling computer, a cycling computer is not a bad tool for the job. Modifying a phone to do a cycling computer's job is like modifying a hybrid bike to do a race bike's job. It can certainly be done, and many people will be satisfied with the results, but ultimately it's not the way to go.

I keep seeing iPhone discussions in the skiing community too. There it makes even less sense than with cycling because the hardware isn't suited to harsh conditions, the GPS antenna isn't nearly as sensitive, the issue with batteries is even bigger, and your life could depend on the device. Yet there are still people that do this.