Custom Frames & Components for Harley Big Twin Motorcycles. The Big Twin Frames collection at TC Bros is built for riders and builders who want a solid foundation for their custom Harley-Davidson Big Twin motorcycles. This category includes expertly designed hardtail frames, frame kits, and essential components that offer unmatched strength, precision, and compatibility. Ideal for models like Softails, Dynas, and other Big Twin builds, these frames are crafted to support bold custom designs while ensuring durability and reliability on the road. Whether you're building a chopper, bobber, or pro-street bike, TC Bros frames provide the quality and performance you need to bring your dream build to life.