Well done on taking this from concept to reality, Vicente. I've been on the hunt for exactly that gadget for a while (only finding companies that ceased to exist) for such an obvious and simple product.
Personally I'm not keen on getting a big and clunky bike computer on my bike, when there's a way to utilize a device I already own, which is smaller an lighter anyway with the same features (using apps like cyclemeter).
I'm definitely getting one of those - Thanks for creating this!