The Hanger Genie is an amazing foldable and precise bicycle tool. It's designed to realign rear derailleur hangers and ensure smooth, accurate gear shifting. Compatible with all wheel sizes from 20˝ to 29˝+, it screws right into the rear derailleur hanger threads. The precise measuring gauge can be locked, so you won't lose your measurement when checking different wheel positions. With its rotating bottom part, you can easily work around the wheel without hitting the frame.

Using this tool is easy. First, screw the tool directly into the rear derailleur hanger threads. Then, you can start checking the alignment of the rear derailleur hanger. Lock the measuring gauge in place before you push it against the wheel at different positions to keep your measurement accurate. When working around the wheel, use the rotating bottom part to avoid hitting the frame. As for maintenance, keep the tool clean after each use. Wipe off any dirt or debris. Store it in a dry place to prevent rusting. If you notice any parts are loose or damaged, it's best to replace them in time to keep the tool working well.