In order to choose the right dropper post, it is important to know all its characteristics. The most important of these are explained in detail below:
Diameter
Depending on the size of the frame, we can find a 27.2 mm dropper seatpost, a 30.9 mm dropper seatpost, a 31.6 mm dropper seatpost or a 34.9 mm seatpost, as the most common sizes. This measurement, in millimeters, refers to the diameter of the lower part of the component that is inserted into the seat tube of the bicycle.
Travel, Total Length and Minimum Insertion
Other important values to consider are the travel length (up and down) and the overall length. In the most extreme disciplines, such as downhill and enduro, the usual travel lengths are higher, logically, from 150 mm to 240 mm, while in disciplines with more stable terrain it is sufficient to lower the saddle a few centimeters, finding travel lengths from 40 mm to 80 mm on gravel bikes, 80 mm to 100 mm for XC and from 125 mm to 150 mm on all mountain or trail bikes.
The overall length of the dropper seatpost will depend on the rider's height and the and frame geometry (with more or less sloping). Larger cyclists will need longer seatposts.
Another important piece of information is to know the minimum insertion measurement in the frame, which is always provided by the seatpost manufacturer, indicated by a line printed on the component itself. In addition, we have to consider and check the length and part of the seatpost that the bike frame, due to its shape, allows us to insert into it. This data can condition the maximum correct height, being too high if there is any impediment to insert the post far enough.
Seatpost Weight
As far as weight is concerned, great value is always placed on the lightest component, although not in the same way for all cycling disciplines. The ideal is to be able to install a lightweight dropper post, adding as few grams as possible to what would be a standard seatpost. This weight difference can easily be between 200 and 500 grams. In fact, the heavier weight is the main disadvantage of this component, together with its higher maintenance. These aspects, by the way, have been greatly improved over the last few seasons.
Trigger Location
There are different possibilities for the location of the remote trigger. Although the manual dropper seatpost, operated by a small lever under the saddle, is one of the types still in the market, most now incorporate a remote trigger that is installed on the bicycle's handlebars.
Remote Trigger Mounting
If we refer to its mounting, we have to consider the type of cable routing, whether it is external or internal, something that will depend on the characteristics of the frame.
Modern bicycles are already prepared to be equipped with an internally routed dropper seatpost and the actuation method will be mechanical (by cable) or hydraulic (hydraulic hose), another variable to take into account.
And we have on the market the wireless dropper seatpost, also known as electronic dropper seatpost or wireless dropper seatpost, with all the advantages of going wireless. Installation is greatly simplified.
Materials
The materials from which these components are made is usually aluminum alloy in its different versions. We are talking about the body and the main parts of the seatpost, obviously there are minor parts made of different materials such as steel, rubber, plastic, etc.
Setback
Depending on our measurements and the size and geometry of our frame, we may or may not need a setback dropper post. As its name suggests, it moves the rider's position slightly back on the bicycle.
Price of Dropper seatposts
As this component has become more popular, the possibilities and the range of available models have increased. The price of a dropper seatpost, therefore, is very wide and will depend, fundamentally, on the set of its characteristics. It will usually be a higher price than a standard seatpost, but the best option, in many cases, will not be a cheap dropper seatpost, and a slightly higher investment may end up being much more profitable and appropriate.