Bike Frame Internal Housing Damper Foam Sleeve Housing Dampener X1.0 Meter Bicycle Shifting Cable - Bicycle Frame - AliExpress
No Hassle internal cable routing trick vid 01 - YouTube
Amazon.com : KOOZER Pack of 3 Meters, Protective Sleeve Slick Tube Liner Cable Suitable for Bike Gear or Brake Inner Cable or Internal Routing for Nokon Systems : Sports & Outdoors
Amazon.com: Yuauy 4m Long Inner Cable Tube Liner Protection Universal for Mountain Bike Road Bicycle Brake Cable Shift Derailleur Cable Replacement : Sports & Outdoors