The biggest challenge our group has had so far is figuring out how our bolt will specifically lock itself onto a bike's tire hub. Our initial idea was similar to that of a simple combination pad lock. However, after creating our CAD file and figuring out the dimensions, we have found that it's going to be more difficult to create a locking mechanism with many small parts than expected because of the small size of the invention. One other problem is finding a place to forge our invention with steel once we are ready to make the final design. Regardless, I am confident that we will figure these things out because we were lucky enough to get in contact with two experts who will act as our mentors for this project. That is probably what I am the most proud of so far, since contacting them was very easy and they have a lot of experience; thus we have a lot of additional support.