Review on 🔧 Enhanced Park Tool IR-1.2 Internal Cable Routing Kit for Optimal Bicycle Frame Maintenance by Chris Hernandez

Those are cables. They are thin enough to fit in your bike. You push them and they chase the magnet. To be honest if I were making mechanical cables I'm not sure I would absolutely need it. If you're buying a frame, ask if it already has brake cable hoses - if it does, you probably don't need it. However, if you are building a bike with Shimano Di2 internal padding, this tool is ABSOLUTELY ESSENTIAL. I don't want to be too frustrated. Di2 cables are flexible and frame tight. It has a wire specially designed for Di2 cables. It has absolutely stopped me from ripping my frame apart in desperation trying to route cables through the downtube, handlebars, chainstay and seat tube. Simply slide through the frame with a magnet, attach the E-Tube cable and pull out the other side. No need to catch cables or guess where the other end is. Bottom Line: If you're building a Di2 bike, JUST GET IT.