Buying guide for best bike seatposts
Bicycle seatposts are one of the most overlooked components on bicycles today. Everyone is focused on the tires, the suspension, the forks, the handlebars, sprockets, pedals, brakes ... in fact, they’re focused on anything but the seatpost.
If bike riders pay any attention at all to the seatpost, it is usually because they’re concerned about the weight of their bike. While that is a valid concern, there are plenty of other matters to keep in mind when considering a seatpost, including how it will affect the smoothness of your ride, the position of your saddle, the proper leg extension you should be employing for various riding situations, and more.
The first thing you have to consider is whether a new or replacement seatpost would physically fit on your bicycle and how it would be attached. If it won’t fit or can’t be clamped or bolted in place, nothing else really matters.
There are other considerations, as well. If you want to know more about bicycle seatposts, keep reading. We’ll walk you through the information and help you make an informed choice in the process.
Key considerations
Size
Diameter: The most important thing to consider is the diameter of the seatpost tube. The seatpost has to have a corresponding diameter in order to fit. Most modern road bikes and mountain bikes (abbreviated MTB) have seatpost tubes that are 27.2mm (standard), 30.9mm, or 31.6mm (oversized). If a seatpost is smaller than the seatpost tube, you can purchase a shim to account for the extra space, but theres’ nothing you can do to get a seatpost that’s too large for the seatpost tube or the wrong shape, so choose accordingly.
Standard seatposts usually offer more comfort when you’re on rough surfaces because they have more give to them, which translates into more shock absorption. Oversized posts are stiffer and stronger, which gives you more power transfer. They also don’t break or bend as easily as the narrower standard seatposts. That strength comes at the price of a rougher ride, though, so be aware of the trade-off.
Length: Longer seatposts are usually more comfortable than short ones, but the amount of exposed seatpost will depend on you, for the most part. Your inside leg length (the inseam, in clothing terms) combined with the physical geometry of your bicycle will determine the longest seatpost you can use.
If there is too much seatpost sticking out of the tube, a couple of problems can occur. First, you’ll become too top-heavy for your bicycle’s frame and design. This may create balance problems at low speeds when you’re cornering or when you’re crossing over rough terrain. To put it simply, you run a higher risk of falling.
The second problem is the leverage ratio. Seatposts have a minimum distance they must be inserted into the tube, usually with a “minimum insertion” line etched on the post. If you don’t insert the seatpost at least to that line, you risk cracking the seatpost tube, leading to a potentially catastrophic failure and an expensive repair job.
Clamps
The clamp is at the top of the seatpost and is the mechanism that attaches to the underside of the saddle. Most modern posts use clamps that are designed to work with twin-rail saddles. Be sure to check that the clamp type you’re considering works with your saddle.
Layback
Here it gets a bit technical. There are two terms, layback and setback, which are often used interchangeably but are actually slightly different. A seatpost can be straight (also known as inline), which means there are no kinks or bends in the post. A seatpost can also be a layback post, which means there is a slight bend or angle at the top of the post that results in the saddle sitting further back from the handlebar than if it was positioned on a straight post.
A setback post is a post where the clamp sits back from the middle of a straight post, that is, not directly in line with the longitudinal center of the post. Again, this puts the saddle slightly farther back from the handlebar, but for different reasons than a layback post. The exact placement of the seat is a matter of personal preference, and some clamps will allow you to further move the saddle forward or backward on the rails.
Features
Material
Most bicycle seatposts are made from one of four different materials. There are pros and cons to each of them.
Aluminum alloy: These seatposts are lightweight, inexpensive, and easy to install. Maintenance is also easy. The downside is that they offer a pretty rough ride.
Chrome-plated steel: These seatposts are very inexpensive. They are usually heavier than the others, too.
Titanium: Titanium seatposts are lightweight but much more expensive than aluminum. On the plus side, they offer a smoother ride.
Carbon fiber: Seatposts made from carbon fiber are usually the most expensive, but they also give you the softest ride. Installation can be tricky, and they require more maintenance than the other types.
Styles
Aero posts: These posts were developed for Tourist Trophy races in Europe. TT racing was originally a motorcycle race first run on the Isle of Man in 1907 but has since added a separate race for bicycles. Instead of the posts being circular, Aero posts are oblong-shaped to cut down on air resistance. These posts will only fit in tubes with an oblong cross-section, though some manufacturers will make the bottom part of the post circular so it will fit into any post tube, then shape the upper part of the post into the oblong blade of an Aero post.
Dropper posts: These are hydraulic seatposts. The height can be dynamically adjusted by means of the hydraulics while you’re on the bike. These are quite popular with mountain bike riders who want to lower the seat out of the way on steep descents then raise it back up again when they reach the bottom. The seat can be raised or lowered with the flip of a switch. The downside, of course, is that hydraulics add additional weight.
Suspension seatposts: These are seatposts with built-in internal springs to cushion the saddle — and your rear end. These aren’t very popular anymore since the need for them has been superseded by improvements in bicycle forks and rear suspension systems. There are still some around, though.
Bike seatpost prices
Inexpensive: The cheapest seatposts run $6 to $12. These are usually chrome-plated steel seatposts with a tapered top to fit into an opening on the bottom of the saddle. These are the old-fashioned type of seatposts.
Mid-range: Seatposts in the $15 to $25 range are higher quality posts manufactured according to strict guidelines. They’ll have etched lines on them to make height adjustment easier. They are usually constructed from aluminum but some will be made from titanium.
Expensive: Above $25 is where you’ll find carbon-fiber seatposts, with laybacks and specialty clamps. Aero posts will be in this price range, too.
Tips
- Never install a seatpost using a hammer. It will get stuck or split the seatpost tube … or both.
- Don’t use grease on a carbon fiber seatpost. The carbon fibers will swell and get stuck.
- Never use a pipe wrench, locking pliers, or any similar tool to remove a stuck seatpost. Use the saddle. It’s already rigidly fixed to the seatpost and will give you the best grip.
- Twist the seatpost back and forth (without raising it) to loosen the grip the tube has on it. Once it breaks loose, raise it straight up without turning it. Turning the seatpost at the same time, as raising or lowering it will leave permanent scratches on the post.
Other products we considered
We like this Sunlite Pillar Suspension Seat Post for its coiled-spring suspension and a collar that allows you to adjust how much play there is in the suspension. It attaches to the saddle with a tapered post, and it is intended to provide a soft ride for an older bicycle that you're still using but want some suspension on it.
We also like the Litetop Carbon Fiber SeatPost. Available in a range of diameters to fit most mountain bikes, it is rugged, lightweight, and tough enough to handle the roughest off-roading you can throw at it. The head is adjustable for maximum comfort, and it has white measurement lines on it to help with height adjustments.
FAQ
Q. What is the best height for a road bike seat?
A. While sitting on the bicycle, move one pedal to its lowest position. Your leg should be straight without having to roll your hips. If you have to roll your hips from side to side or your knee is bent, move the seatpost up or down as needed.
Q. Should a mountain bike seat be the same height as a road bike?
A. No. For a mountain bike, adjust the seatpost up or down until your leg is slightly bent when the pedal is at the lowest position.
Q. What seatpost should I use for downhill riding?
A. Downhill riding is different from cross-country riding. You need a layback or setback seatpost to move the saddle further toward the rear of the bike (away from the handlebar). This puts more of your weight above the rear tire and helps keep you from falling forward over the handlebars.
