Ideal for riders replacing a worn stock seatpost collar on a bike with a standard round seat tube and an aluminium seatpost.
If your current collar is tired, corroded or no longer holding saddle height properly, the PRO Alloy Seatpost Clamp is an easy fix. It uses a robust alloy body with a single stainless steel bolt and nut, plus hex-key actuation for a clean look and dependable clamping on bikes that use a conventional external seatpost clamp.
This is the kind of part that suits riders who just want a simple, workshop-friendly replacement rather than a flashy upgrade. The three available sizes — 28.6 mm, 31.8 mm and 34.9 mm — cover some of the most common round seat tube standards, and the black finish keeps things neat on almost any build.
The main thing to get right is sizing and seatpost material. This clamp is intended for aluminium seatposts only, so it is not the pick if your bike runs a carbon post. As with any seatpost collar, correct fit matters more than brute force: measure the outside diameter of the frame’s seat tube at the clamp, not the seatpost itself, and install it with the right assembly compound for your frame and post materials.
Alloy construction
A solid metal clamp body built for everyday use on commuter, road, gravel and MTB bikes with a standard external collar.
Hex-key actuation
Cleaner and more secure than a quick-release style if you prefer a tidy setup and rarely change saddle height mid-ride.
Stainless steel bolt and nut
Durable hardware that is better suited to repeated adjustments and general weather exposure than basic plated fittings.
Single-bolt design
Simple to fit, easy to service and quick to adjust with a standard workshop hex key.
Three common sizes
Available in 28.6 mm, 31.8 mm and 34.9 mm to suit a wide range of bikes using round external seatpost clamps.
Black finish
Easy to match with most frames and finishing kit for a clean, understated look.
Replacement-friendly format
A practical choice when your original clamp is slipping, cracked, corroded or missing hardware.
General
Materials & construction
Dimensions & weight
Compatibility
Sizing
Features
What's included
Great for
Maybe not for
Choose 28.6 mm, 31.8 mm or 34.9 mm to match the outside diameter of your frame’s seat tube at the clamp. Do not size from the seatpost diameter. Seatpost clamp fit can vary slightly with frame tolerances and paint thickness, so measuring with calipers is the safest option. This clamp is listed as suitable for aluminium seatposts only.
vs Bontrager Basic Seatpost Clamp
A similar no-frills external clamp for riders who simply want a standard replacement collar.
vs Wolf Tooth Dual-Bolt Seatpost Clamp
A more specialised premium option aimed at bikes that are difficult to keep from slipping.
Measure the frame, not the post
Seatpost clamp size is based on the outside diameter of the frame’s seat tube, not the seatpost. If you measure the wrong part, the clamp may never tension correctly.
Best for aluminium-post bikes
Because this model is listed for aluminium seatposts only, it makes the most sense on metal-post setups where you want a clean, dependable collar without paying for carbon-specific hardware.
Don’t fix slipping with brute force
If your saddle height keeps dropping, clean the frame and post first and use the correct assembly compound for the materials involved. Over-tightening a seatpost clamp is a fast way to damage parts.
A hex-key clamp suits set-and-forget riders
If you rarely move your saddle height, a bolt-up collar like this is neater and less fiddly than a quick-release clamp.
Pro is a cycling component and accessory brand focused on contact points, tools and finishing kit for road, gravel, mountain bike and triathlon riders. Its range covers handlebars, stems, saddles, seatposts, bar tape, workshop tools and on-bike accessories, with product development centred on fit, function and rider feedback.
The brand is closely linked with high-performance cycling and develops products through collaboration with riders, designers and Shimano Dynamics Lab. Pro supports elite athletes across multiple disciplines, but its catalogue is aimed broadly at riders who want practical, performance-led equipment for everyday riding and racing.
