Seatposts
Used MTB seatposts from UK sellers — dropper posts, rigid posts and replacement internals. Listings cover RockShox Reverb, Fox Transfer, OneUp, BikeYoke, PNW, KS, Thomson and more. Match the diameter, length and travel to your frame before you buy.
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Is a dropper post worth fitting?
A dropper post is the single biggest upgrade you can make to a mountain bike's capability, and the one MTB component most worth prioritising. Being able to drop your saddle on the fly transforms descending confidence and lets you ride terrain that would be sketchy with a fixed post. If your bike doesn't have one, it should.
Which dropper post should I buy?
Modern dropper posts are hydraulically or mechanically actuated — press a remote lever on the handlebar and the post drops to a preset travel. RockShox Reverb is the most common: reliable, widely supported, with good aftermarket rebuild kits. Fox Transfer is lighter with a smoother action. OneUp V2 and BikeYoke Revive are the enthusiast favourites — both mechanically simple, easy to service, with excellent long-term reliability records. PNW and Brand-X offer strong budget options.
What diameter and travel do I need?
Seatpost diameter must match your frame's seat tube internal diameter exactly — 30.9mm and 31.6mm are the most common MTB standards, with 34.9mm appearing on newer frames. Travel options range from 100mm to 240mm, and more travel is generally better because it lets you get the saddle further out of the way on descents. Your maximum travel is limited by frame insertion depth: measure from the minimum insertion mark to the seat collar, subtract 50mm for safety, and that is your maximum usable travel.
Internal or external routing?
Internally routed droppers run the cable through the frame — cleaner look, less cable exposed to damage, but harder to install and maintain. Externally routed posts clamp the cable housing to the frame exterior, which is easier to set up and troubleshoot. Most modern frames have internal routing ports for the dropper; if your frame only supports external routing, OneUp and PNW make excellent externally routed options.
When does a rigid post still make sense?
Rigid posts still have their place on XC race bikes where every gram matters, hardtails with short seat tubes that can't fit a dropper, and bikes where simplicity is the priority. Thomson Elite is the benchmark, with precise tolerances and bombproof construction. Alloy is the practical choice: carbon posts save 50-80g but are harder to clamp safely — carbon paste required, torque wrench essential — and less forgiving of crash damage.