There are only a few times you’re likely to think about your seatpost, when you initially build your bike, and if/when it breaks. While dropper posts are becoming increasingly more popular because they allow you have a tall post on the uphill, and move it out of the way on the way down, they also add a degree of complexity and weight.
Cross-country races are still won on the climbs and the fewer grams you have to lug up the hill with you, the better. Not only will the right seatpost potentially offer a smoother ride, but it can also help you achieve a better bike fit and shed grams, too.
BEST SEAT POST: EVERYTHING YOU NEED TO KNOW
The most common seatpost diameters are 27.2mm, 30.9, 31.6 and 34.9mm - which one you need will be determined by your frame of choice. Only steel frames and a shrinking number of XC bikes will accept the 27.2mm posts. A thinner diameter seatpost will inherently have more flex and will likely make for a slightly more comfortable ride however, a wider or 'oversized' post is less likely to break and will add stiffness for optimal power transfer.
If you're after a skinny post, and your frame is designed around one of the bigger standards, there are shims available, but make sure you apply a layer of grease if its metal-on-metal to prevent everything from bonding together.
Your frame will also determine the maximum seatpost length. With contemporary mountain bike kinematics becoming lower, longer and slacker, the result has culminated in longer seatposts. While hardtails don't often have insertion issues, full-suspension frames may have pivots in the seat tube which limit how far down a seatpost can go. Luckily, unlike droppers, rigid seatposts can be cut to length.
Like handlebars, frames and wheels, seatposts come in a variety of materials, the most common being aluminium and carbon fibre. However, you can find boutique versions made from materials such as titanium. As always, carbon commands a higher price tag, usually weighs less and dampens more vibration but also tends to break more often.
3. Setback and Layback
While they may sound like the same thing, layback and setback are two separate measures. Layback seatposts have a bend near the top of the post, while set back is the degree which the seat clamp sits behind the top of a straight seatpost.
Dropper posts are increasingly popular because they allow you to climb with a full-height post, and also move it out of the way when you’re descending. Overall they are becoming more reliable, and with the advent of 1x drivetrains, the gear shift style remotes allow for effortless operation.
If you're thinking of upgrading to a dropper post, check out our guide to the best dropper posts of 2020.
5. Saddle rail clamp
Most mountain bike saddles use a two-rail system, however not all two-rail saddles are compatible with all seatposts. Saddles with alloy rails will have 7mm, round rails, while most carbon-railed saddles see 7 x 9mm oval rails.
THE BEST RIGID SEAT POST YOU CAN BUY
Ritchey's Comp 2-bolt seatpost is made from 3D-forged 6061 aluminium and is topped with a low-profile clamp that's easy on lightweight seat rails. Instead of the clamp bolts being situated on the front and back, each rail gets its own bolt for the greatest contact area with the saddle for maximum hold.
With 25mm of setback, the post is claimed to weigh 250g and comes in 27.2, 30.9 and 31.6mm diameters, and 300mm, 350mm and 400mm lengths.
Thomson's Elite seatpost has long-been considered the gold standard of adjustability, strength and performance when it comes to supporting your seating arrangements. Made from a single piece of machine 7000-series aluminium, it weighs about 200g depending on the size and diameter.
The Elite seatpost is available in both straight and layback versions, the brand said its design incorporates a bending fuse to prevent catastrophic failure, and the head clamp and upper tube can withstand 350 foot-pounds of torque.View Deal
Slotting in as Easton's top-end aluminium seatpost, the EC70 gets a low-profile clamp design and is made from the brand’s TaperWall tubing.
Previous versions had durability issues with the clamping mechanisms, luckily Easton has updated the design to a forged dual-bolt clamp. The new black anodised post is ready to support your saddles for hours on end without draining your bank account.
With its Hunter head design that features angled bolts for easy tool access, the thumbscrew tightening system makes dialling saddle angle a considerable less expletive-inducing process. The head is suitable for 7mm alloys rails and oval carbon rails, with a wide lower cradle for rail support.
Only available as a straight post, the Next SL is finished in 3k carbon and comes with a rubber grommet to prevent water and mud from finding its way into your seat tube.
Just because the Pro Tharsis carbon seatpost has XC in the name, doesn’t mean that it’s reserved for lightweight cross-country bikes. While the T-8000 carbon post is feathery enough to please XC whippits, the Tharsis is strong enough for trail riding if a dropper isn’t really your thing.
The single-bolt clamp holds the offers a no-slip grip on saddle rails and provides for easy adjustment and tool access - and for those running XTR or XT Di2, it will hang onto your battery.
Like a shot of 30-year single malt, the Whisky 7 post is smooth. The unidirectional carbon seatpost absorbs trail chatter, and it's abundantly stiff so no energy is lost to unwanted flexing or twisting.
Available in two offsets, the straight version features angled hex bolts, while the offset version sees a hex bolt and a thumb dial to simplify saddle angle adjustments. It's not the lightest option at 260g, but it's affordable as far as carbon options go.View Deal
At 400mm in length, the Enve Seatpost is available in 0mm and 25mm offset versions. While quite a few carbon posts see a metal clamp head bonded on the top, the ENVE post is carbon through and through.
The Twin Link clamp uses two bolts with expanding wedges to adjust saddle angle and are easily accessible from the sides below the rails. The post comes in sizes from 24.5 up to 31.6 and is claimed to weigh 204g in the 20.9mm guise.View Deal
German outfit Tune is best known for its crazy light components, and the 180g (27.2mm x 340mm) Starkes Stück post is no exception.
Made from CNC milled 7075 aluminium, the straight post gets a mix of carbon and titanium hardware to grasp your saddle.
Tune says the ultralight post has its own' internal strengthening' and it comes in a range of anodised colours with laser-etched logos to match any bike. View Deal