I’ve stitched the mid and foreground sidewalk and street. This involved a lot of circular stitching. I like to use variegated threads for this kind of stitching because they blend easily and create variation on the surface. 
After that I started stitching the bike frame. This takes a bit more attention. I chose 10 threads total that range from very light to very dark, I put down the middle value thread first and then worked to the lightest thread. Now, I need to go back and put down the darker threads, and do some fine tuning. A key factor will be breaking up the highlights and the accents so that they come and go.