Kryptonite Transit FlexFrame-U U‑Lock Mount One Size Modern — Lightweight Frame Bracket for 13mm & 16mm Shackles

The Kryptonite Transit FlexFrame-U Bracket is a lightweight, universal bike mount that carries most Kryptonite U‑locks (13mm and 16mm round shackles) securely on your frame for easy transport.

Designed to make carrying a U‑lock simpler and less intrusive, the Transit FlexFrame‑U bracket fastens to tube sizes from 25mm up to 80mm and adapts to round, oval, triangular or square tubing. It’s built with a heavy‑duty soft strap system that contours to your bicycle’s frame so the lock rides stable and out of the way on commutes, errands, and rides around town. Note that the bracket does not fit the NY Fahgettaboudit or Messenger series U‑locks.

How does the Transit FlexFrame‑U attach to different bike frames?

The bracket uses a flexible strap system that wraps and tightens around the bike tube, creating a secure hold without metal-to-metal clamping. Its design accommodates a wide range of tube shapes and sizes so installation is straightforward on most bikes.

• Fits tubing diameters from 25mm to 80mm
• Compatible with round, oval, triangular, and square frame shapes
• Soft strap contours to frame to reduce rattling
• Quick mount and removal for shared or multi‑bike use

Which Kryptonite U‑locks will this bracket carry?

The Transit FlexFrame‑U holds Kryptonite U‑locks with 13mm and 16mm round shackles—covering many of the brand’s common models. It’s not compatible with the bulkier NY Fahgettaboudit and Messenger series, so double‑check your lock model before buying.

• Supports 13mm round shackle U‑locks
• Supports 16mm round shackle U‑locks
• Excludes NY Fahgettaboudit and Messenger series
• Works with most Kryptonite U‑locks of matching shackle size

Will it damage my bike’s paint or interfere with riding?

The soft strap and contoured support are designed to minimize contact pressure and movement, reducing abrasion and rattling while riding. For best protection, install on a clean section of frame and avoid overtightening; a thin layer such as protective tape can be added if you’re concerned about finish wear.

• Soft materials reduce friction against paint
• Low‑profile placement keeps the lock out of the rider’s knees
• Strap tension prevents bouncing on rough roads
• Optional frame protection recommended for delicate finishes

How easy is it to mount and remove the bracket?

The Transit FlexFrame‑U is made for fast installation and removal so you can move it between bikes or take it off when not needed. The flexible strap system tightens quickly and the bracket locates the U‑lock for simple insertion and removal during daily use.

• Quick strap fastening for tool‑free installation
• Simple positioning for repeatable placement
• Fast lock insertion and release while parked
• Lightweight design for minimal carry weight

Who is this for? The Kryptonite Transit FlexFrame‑U bracket is ideal for cyclists who want to carry a robust U‑lock without using a backpack or bag—commuters, urban riders, and bike messengers who use compatible Kryptonite locks will appreciate the low profile and adaptable fit. If you own a NY Fahgettaboudit or Messenger series lock, check Kryptonite’s other mounting options; otherwise the Transit FlexFrame‑U offers a practical, lightweight way to transport most 13mm and 16mm Kryptonite U‑locks.