Bicycle seatpost , seatpin , saddlepole , gable pillar , or saddle pin is a tubes that extend upward from the bike frame to the saddle. The number that comes out of the frame is usually adjustable, and there is usually a sign that indicates minimum insertion (or maximum extension). Seatpost can be made of steel, aluminum, titanium, carbon fiber, or aluminum which is wrapped in carbon fiber.
Video Seatpost
Poin lampiran
Seatposts generally clamp directly into the saddle rails by which they must be compatible, while the old or cheap seatposts slide into separate clamps which then clamp the saddle rails.
To attach it to the main frame of the bike, the seatpost is inserted into the seat tube, which should have a slightly larger diameter (or a cylindrical shim can be used). The seatpost is held in place by pressing the top of the seat tube with a tightening ring (while reducing its diameter; the vertical slit cut into the tube allows this to occur without squeezing) until the tube firmly hugs the post where it leaves the frame. A hole for pinch bolt (also known as "binder bolt") can be built into the frame for this purpose, or "seat post clamp" can be purchased separately (but must be sized to fit the tube seat diameter). Whether integrated or separate, the seat post bolt can have a simple nut, it can be an Allen bolt, or it can include a quick discharge mechanism, with a grip that releases the clamp without a tool. The quick release allows easy seat height adjustment, although increasing the risk of seat theft unless it is also used to release the seat when parking.
Maps Seatpost
Size
The size of the seatpost depends on the internal dimensions of the seat tube of the bicycle frame. They come in different diameters, lengths and offsets. The offset is the distance between the centerline of the seatpost tube, and the center line of the clamp area. Shims are often available to fit the too small seatpost into an over-sized seat tube.
Diameter
The seatpost diameter generally ranges from 22 mm to 35 mm with the addition of 0.2 mm. The most common size is 27.2 mm (1.07 inches) for most bikes, especially for higher-quality models. BMX bikes generally use 25.4 seatposts. On some modern bikes with thick alloys or carbon tubes, larger diameters like 30.9 mm are used. Tapering seatposts often have a diameter of 22.2 mm (7/8 inches) at the top.
Sheldon Brown collects and publishes a list of post-seat diameters on its website, evidence of a common problem in finding compatible replacements.
Length
Lengths range from 75 mm to 430 mm. Seatpost mountain bikes tend to be longer than street bike seatposts.
Offset or layback
Offset or "layback" can range from 0 mm to 45 mm. An offset seatpost is required when the corner of the seat tube from the frame is too steep to give the desired saddle setback (horizontal distance between perpendicular lines hanging from the saddle nose and bottom bracket spindle). In contrast, "inline" posts may be required if the tube angle is too loose. Some saddles, especially the Brooks leather saddle, have relatively short rails, allow for fewer adjustments to setbacks, and changing the seatpost may be the only way to achieve the correct position.
Type
Plain
This type, usually found on older bikes, cheaper bicycles, or children's bikes, consists of a tube that can lower the diameter for the last inch or more (2.54 cm) and a separate clamping mechanism at the top. One bolt tightens the clamp to the rest of the seatpost and into the saddle rail at the same time.
Micro customizable
They can be divided into two types; which can adjust the saddle angle continuously, and which is where the saddle angle can only be adjusted to a certain number of positions.
Integrated
Multiple road frames and high end bike tracks are made of a single piece of carbon fiber formed with integrated seatpost that is cut lengthwise depending on the rider, also known as the seat mast. The advantage is lighter, can be shaped into aerodynamic shape, and eliminates the need to clamp the shape of an irregular tube. The disadvantage of this arrangement is that the seatpost height can not be adjusted. Usually there are 2-3 centimeters adjustment with the clamping device.
Aero
As an alternative to the above mentioned integrated seatpost, some seatposts only have aerodynamic shapes that match the aero seat tube shape or are not rounded over a certain point. In the case of aero seat tubes, there are various clamping mechanisms for seatposts such as those that include bolts and pinch slices.
Suspension
The seatposts suspension allows the saddle to move up and down by telescoping or parallelogram mechanisms and incorporating springs, elastomers, or compressed air and possibly silencers to protect against bumps. Preload from spring can be adjusted. Seatposts are most common on hybrid and mountain bikes. Suspension seatpost usually comes in fewer diameter, and more shims may be required.
Pivotal
Important seatposts are common on BMX bikes. They have a concave half-circle of ridge above them that matches the semi-circular convex ridges at the bottom of the important saddle. The two semicircles were held together with a bolt to attach the saddle to the seatpost. The important seatposts are currently growing rapidly in popularity with mountain bikes.
Seatmast and cap
Some bikes, such as the Madones Tracks, provide saddle height adjustment with seat and hat settings. The seatmast is an extension of the seat tube over the top tube, and the lid slips into it, clamps in place, and attaches to the saddle.
Dropper
Seatposts dropper on mountain bikes can be shortened remotely using the controls on the handlebar to move the saddle out of the way in the technical section.
InterLock
InterLock rear seats are similar to the seatpost type integrated in the function. But the patented technology has a bike lock hidden inside it, which stays inside the bike frame when it is stored.
Maintenance
Seatposts should be periodically removed from the frame, cleaned, oiled and reassembled to prevent seatpost seize within the frame. This is especially important with bikes that do not have mudguards (fenders) that are regularly ridden in wet conditions. It should be careful not to overly tighten the bolt or fast release lever that staples the post within the frame, especially if it works on two brazing lugs rather than a separate clamp collar. Overtightening can bend or crush the frame lugs or peel the threads on the collar apart. The metal seatpost should be well lubricated, with a slot in the seat tube of the bike also filled with oil stains. This helps prevent water from flowing into the seat tube.
There is some controversy about whether the carbon grease seatposts or not. There seems to be no consensus. Now there is a special product, called "carbon preparation" or "carbon paste", specifically for the interface between carbon and most other materials.
References
External links
- seatpost database size by Sheldon Brown
Source of the article : Wikipedia
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