Bicycle Seatpost Adapter Shim Sleeve 25.4/27.2/28.6/30.1/30.4/30.8/31.6/33.9/34.9/36mm
$3.24
SKU: N-SEAT001
Brand: CATAZER
- Material: Made from high-strength aluminum alloy, lightweight durable
- CNC Precision Machining: Precision-engineered for excellent anti-slip performance. Smooth surface protects both seatpost and frame.
- Conversion Options: Available in sizes from 25.4mm to 36mm – find the perfect match for your seatpost and frame tube.
- 60mm Length: Standard length provides ample contact area for secure clamping without adding unnecessary weight.
- Universal Compatibility: Suitable for mountain bikes, road bikes, electric bikes, BMX, fixed gear, and more. Easy to install.
- Description
- Additional information
- Reviews (0)
Description

Product Overview
Upgrade your bike’s fit with the Bike Seatpost Adapter Shim Sleeve, precision-engineered to allow a smaller diameter seatpost to fit securely into a larger seat tube. Whether you’re swapping components, upgrading your frame, or building a custom bike, this adapter sleeve ensures a perfect, wobble-free connection.
Crafted from high-quality aluminum alloy and CNC machined to exacting tolerances, the shim provides excellent anti-slip performance, protecting both your seatpost and frame from scratches and movement.
Specifications
- Material: Aluminum Alloy
- Length: 60mm
- Size Options

How to Install Bicycle Seatpost Adapter Shim
- Measure your components – Determine the outside diameter of your seatpost and the inside diameter of your frame’s seat tube.
- Select correct shim – Choose the bike seatpost shim that matches your conversion needs (e.g., 27.2mm post to 31.6mm tube).
- Insert shim into frame – Slide the shim into the seat tube. Ensure it’s fully seated and aligned.
- Insert seatpost – Place your seatpost into the shim. Adjust to desired height.
- Tighten seat clamp – Secure the seatpost clamp to the recommended torque. Ensure post does not slip.
- Test and ride – Gently test the seatpost for movement. If secure, you’re ready to ride.

Package Include
- 1 x bike seatpost adapter shim sleeve
Additional information
| Weight | 0.1 kg |
|---|---|
| Dimensions | 10 × 8 × 3 cm |
Leave your review
Rating
Publish review
Related Products
-
Brake Calipers, Brakes, Components
Bicycle Disc Brake Adapter Converter Aluminum Alloy Rim to Disc Brake
$13.65 - $16.860 - 0 reviewsThere is no AI review summary.Select options This product has multiple variants. The options may be chosen on the product pageQuick View -
Brake Levers, Brakes, Components
Lightweight Aluminum Alloy Mountain Bike Disc Brake Lever with Bell
$16.290 - 0 reviewsThere is no AI review summary.Select options This product has multiple variants. The options may be chosen on the product pageQuick View -
Components, Headsets, Parts & Stem
Profession Bicycle Headset for 1-1/8″-1-1/2″ Tapered Tube for Road/TT/MTB Bicycle
$14.860 - 0 reviewsThere is no AI review summary. -
Components, Grips, Parts & Stem
PU Leather Bike Handlebar Grips Wear-Resistant Anti-Slip with Double Lock-on
$5.270 - 0 reviewsThere is no AI review summary. -
Bottom_Brackets, Components, Drivetrain_Gears
Square Taper BSA Bottom Bracket 68mm Multiple Spindle Sizes 103/107110.5/113/116/118/120/122.5/124.5/127.5mm
$6.48 - $8.000 - 0 reviewsThere is no AI review summary.Select options This product has multiple variants. The options may be chosen on the product pageQuick View
- Description
- Reviews (0)
Description

Product Overview
Upgrade your bike’s fit with the Bike Seatpost Adapter Shim Sleeve, precision-engineered to allow a smaller diameter seatpost to fit securely into a larger seat tube. Whether you’re swapping components, upgrading your frame, or building a custom bike, this adapter sleeve ensures a perfect, wobble-free connection.
Crafted from high-quality aluminum alloy and CNC machined to exacting tolerances, the shim provides excellent anti-slip performance, protecting both your seatpost and frame from scratches and movement.
Specifications
- Material: Aluminum Alloy
- Length: 60mm
- Size Options

How to Install Bicycle Seatpost Adapter Shim
- Measure your components – Determine the outside diameter of your seatpost and the inside diameter of your frame’s seat tube.
- Select correct shim – Choose the bike seatpost shim that matches your conversion needs (e.g., 27.2mm post to 31.6mm tube).
- Insert shim into frame – Slide the shim into the seat tube. Ensure it’s fully seated and aligned.
- Insert seatpost – Place your seatpost into the shim. Adjust to desired height.
- Tighten seat clamp – Secure the seatpost clamp to the recommended torque. Ensure post does not slip.
- Test and ride – Gently test the seatpost for movement. If secure, you’re ready to ride.

Package Include
- 1 x bike seatpost adapter shim sleeve
Leave your review
Rating
Publish review
Related Products
-
Brake Calipers, Brakes, Components
Bicycle Disc Brake Adapter Converter Aluminum Alloy Rim to Disc Brake
$13.65 - $16.860 - 0 reviewsThere is no AI review summary.Select options This product has multiple variants. The options may be chosen on the product pageQuick View -
Components, Pedal Adapter, Pedals & Cleats
Clipless Pedal Adapter For Shimano SPD Compatible Bikes
$6.78 - $8.370 - 0 reviewsThere is no AI review summary.Select options This product has multiple variants. The options may be chosen on the product pageQuick View -
Components, Saddles, Saddles & Posts
Front Mounted Child Bike Seat for Kids Up to 30kg Adjustable
$18.790 - 0 reviewsThere is no AI review summary. -
Components, Saddles, Saddles & Posts
Kids Balance Bike Saddle Replacement Compatible with 22.2mm Diameter Seatpost
$12.000 - 0 reviewsThere is no AI review summary. -
Components, Saddles, Saddles & Posts
Lightweight EPU Hollow Bike Saddle 338g Shock Absorption Ergonomic Design
$14.770 - 0 reviewsThere is no AI review summary. -
Bar Tape, Components, Parts & Stem
Napa Leather Retro Bicycle Handlebar Tape 2 Rolls with End Plugs
$14.35 - $17.710 - 0 reviewsThere is no AI review summary.Select options This product has multiple variants. The options may be chosen on the product pageQuick View















































