The Lyne Seatpost Shim 30.9 to 31.6mm is a precision-machined adapter that allows a 30.9mm seatpost or dropper post to be fitted into a bicycle frame with a 31.6mm seat tube. It is made from lightweight 6061-T6 aluminium and is designed specifically for a precise, secure fit.
Key Features
- Converts a 31.6mm frame to accept a 30.9mm seatpost
- Precision-machined construction
- 6061-T6 aluminium alloy
-
120mm length for extended support inside the seat tube
- Lightweight at just 9g
- Suitable for standard seatposts and compatible dropper posts
Specifications
| Specification |
Details |
| Brand |
Lyne Components |
| Product |
Seatpost Shim |
| Seatpost Diameter |
30.9mm |
| Frame Seat Tube |
31.6mm |
| Internal Diameter |
30.9mm |
| External Diameter |
31.6mm |
| Length |
120mm |
| Material |
6061-T6 Aluminium |
| Weight |
9g |
Benefits
-
Expands seatpost compatibility: Allows a 30.9mm post to be used with a 31.6mm frame.
-
Lightweight: Adds only 9g to the setup.
-
Precise fit: Precision machining provides a close-fitting interface between the post and frame.
-
Durable: 6061-T6 aluminium provides a strong and corrosion-resistant construction.
Compatibility
This shim is specifically designed for 30.9mm seatposts in 31.6mm seat tubes. It is particularly useful when you have a preferred 30.9mm dropper post but your frame requires a 31.6mm post diameter.
Important: Do not use this shim to fit a 31.6mm seatpost into a 30.9mm frame. The shim works in the opposite direction: 30.9mm post → 31.6mm frame.
Best Suited For
- MTB seatposts
- Dropper-post installations
- Custom bike builds
- Riders upgrading or replacing a seatpost
- Frames with a 31.6mm seat tube where a 30.9mm post needs to be installed
