I've searched around on the forums, but I must not be using the right words to narrow my search. So I used that as an excuse to draw up a very rough sketch of my idea/question:

Does a product exist that would allow me to use my road or commuter bike to tow my mountain bike to a trail head? I have two local mountain bike trails that are 4.5 and 8 miles away from my home. I don't mind riding the mountain bike to those to go riding. However, there are trails that are in the neighborhood of 15-30 miles away that I would be comfortable riding to and from, but NOT on stubbies. Also, this would be a great option for taking my mountain bike to the shop when I break things, and in all cases avoiding driving a car. I often have difficulting mentally resolving the concept of DRIVING to a BIKE trail.

Here's the sketch. Anyone have any ideas? Improvements? Does a product exist, or will I be making my own? The idea is to only catch the front wheel (but securely) so that the frame and rear wheel are free to turn (a la any other "trailer"). Many thanks!