I've thought about this problem a lot, and was thinking about building something similar. This idea is essentially Lockitron, except it's more mobile (both w.r.t the door/bike, and to w.r.t. its physical location). That mucks with two things: a) the lock isn't attached to the bike, like a Lockitron is attached to its door, and b) the lock doesn't have 24/7 data access, unlike most Lockitrons.<p>a) makes it far less convenient to unlock. Sure, the lock might unlock itself when I'm near it, but then what happens? Does the lock just fall to the ground? Do I still have to remove the lock from my bike? If so, how is this better than a combination lock?<p>b) makes it impossible to unlock remotely. Sure, it's great that I can tell my friends the exact location of my bike, but what's the purpose of that if I can't unlock it for them from afar? They still need my phone (effectively physical presence) before they can unlock and use my bike. If I had a combination lock, I could just tell them my passcode and they would be off. Why not just a combination lock?<p>These two problems make it unappetizing for customers. There seem to be a few main reasons why you have a Lockitron: 1) to go through the door without fishing your keys out or fudging with the lock, 2) so you can let other people in when you're not there, and 3) to know when people entered your house. In fact, these are pretty much the exact reasons Lockitron touts on its website: <a href="https://lockitron.com/preorder" rel="nofollow">https://lockitron.com/preorder</a>.<p>If a) and b) are true, most of the above three points have been not been addressed. 1) is a direct result of assumption a), and 2) and 3) are direct results of assumption b).<p>These problems aren't insurmountable, though. For a), some locks are physically attached to the bike. Here's an example of one: <a href="http://lovelybike.blogspot.com/2011/02/is-wheel-lock-useful-feature.html" rel="nofollow">http://lovelybike.blogspot.com/2011/02/is-wheel-lock-useful-...</a>. That way, when you walk up to the bike, it unlocks itself, and when you walk away, it locks itself. There's no need for any physical interaction between you and the lock. For b), you could include a cellular modem [1], which would allow you to remotely unlock your bike. Even more important, however, would be the added benefit of being able to track your bike if it were to be stolen (since with a "cafe lock" like the one I linked above, somebody could very well just carry it off).<p>1. The problem is trying to find a suitable data plan. The ideal one would be pay per kilobyte, with the SIM lasting forever. Since unlock and location requests take up very little bandwidth, you could pay a small amount, like $10, for a few megabytes. That should be enough for quite a few requests.