Dropper Posts
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Dropper posts – More control and comfort on any terrain
Dropper posts – also known as telescopic seat Posts or adjustable seat posts – allow the saddle height to be flexibly lowered and raised directly while riding. Originally a hit in the mountain bike sector, they improve freedom of movement on the bike and provide more control in demanding terrain. Nowadays, they no longer only demonstrate their advantages on MTBs, but also on gravel bikes, hybrid bikes and city and urban bikes, where they not only make getting on and off the bike easier in everyday life.
In order for a dropper post to function reliably and be correctly integrated into the frame, several technical factors must be taken into account.
Internal structure – how dropper posts work
Dropper posts consist of several tubes that slide into each other and can be locked or released by an internal mechanism.
- Hydraulic-pneumatic systems:
A closed oil-air cartridge combines hydraulic damping with an air spring (not to be confused with a suspension). The air pressure serves as counter-tension to reset the seat post, while oil flows regulate the speed. - Mechanical-hydraulic cartridges:
A mechanical impulse (e.g. via a cable pull) is used to unlock a hydraulic cartridge. The system is low-maintenance and durable. - Mechanical locking:
On simple models, the locking is purely mechanical via latching positions. These systems are often inexpensive, but do not offer infinitely variable adjustment. They tend to lead a niche existence on the market.
Telescopic guides and sleeve bearings:
The tubes are stably connected to each other via guides and sleeve bearings. High-quality models also use sealed bushings and bearings for smooth travel with minimal play and high durability.
Wear, maintenance and care:
Adjustable seat posts are subject to mechanical wear and should be serviced regularly. Observe the respective manufacturer's instructions.
Also see Care instructions for dropper posts.
Technical dimensions – it has to fit
The following dimensions play a key role in selecting the right dropper post:
- Shaft diameter:
Common sizes include 27.2 mm, 30.9 mm, 31.6 mm and 34.9 mm – the diameter must match the seat tube of the frame exactly. A larger seat tube diameter can usually be adapted using a suitable reduction sleeve. However, this can impair the function of some models, as they may react sensitively to irregular pressure loads. - Travel:
Depending on the model, the travel ranges from around 75 mm to well over 200 mm. The appropriate travel length depends on rider size, frame size, riding position and intended use. - Stack height:
For adjustable seat posts, the stack height refers to the distance from the upper edge of the seat tube (equivalent to the lower edge of the seat post clamp) to the centre of the saddle rail (at maximum insertion depth).
The minimum stack height indicates how high the seat post is when lowered, the maximum height indicates how high the seat post is when raised. Both values are helpful in determining the maximum travel. - Overall length:
Important for achieving the optimum seat height – with small frames or limited space in the seat tube, special attention must be paid to the overall length (as well as the height). - Insertion depth:
The minimum insertion depth that the seat post must be inserted into the seat tube and the maximum insertion depth that the seat post can be inserted. The frame must be dimensioned accordingly, taking into account the optimum seat height and the desired adjustment range. - Offset:
A few models have a saddle head that is offset to the rear for fine adjustment of the riding position. Today, however, models without offset are more common.
Mounting and control – mechanical, hydraulic, electronic or on the saddle
Dropper posts are operated using different mechanisms, each of which has different requirements and advantages:
Types of operation:
- Mechanical (Bowden cable):
It is operated via a lever on the handlebars, which activates the mechanism inside the seat post via a cable pull. Robust, precise and suitable for many frame types. - Hydraulic:
A less common but very direct solution. This is also controlled by a handlebar lever, but via a hydraulic line. The actuation is particularly sensitive. In addition, the extension speed of the seat post can often be influenced directly on the remote lever. - Electronic:
Wireless, radio-controlled systems offer a minimalist appearance and simple installation. No routing of cables or lines – but often expensive. Particularly suitable for modern bikes with additional electronic equipment (e.g. electronic shifting). If compatible, electronic seat posts can be integrated into the overall electronic system of the bike. - Directly under the saddle (mechanical):
The control lever may be located directly under the saddle, especially on simpler or cheaper models. The seat post is unlocked by pushing or pulling. This solution is particularly suitable for city, hybrid or gravel bikes without the option of a handlebar remote control – with the advantage of easy mounting.
Cable routing:
- Internal (Stealth Routing):
The cable runs through the frame – ideal for modern bikes with internal cable routing and a minimalist look. Check whether your bike fulfils the necessary requirements. - External:
The cable is attached to the outside of the frame – an advantage for older frames, easy to maintain and uncomplicated to retrofit. - Electronic:
What exactly is cable routing?
Intended use & advantages at a glance
Mountain bike (cross-country, trail, enduro)- Dynamic lowering of the saddle on technical descents
- More freedom of movement and riding safety
- Better weight transfer off-road
- Reduced risk of OTB crashes or loss of control
Gravel
- Improved stability on descents with loose surfaces
- Relief for short technical passages or obstacles
- More efficient body position on changing terrain
Hybrid & Tour
- More comfortable mounting and dismounting – especially with luggage racks or panniers
- Safe riding in urban or mixed terrain
- Quick adjustment of the saddle height for a secure position at traffic lights, other stops or steep passages
Care instructions for dropper posts
Regular maintenance of your telescopic seat post ensures that it will function reliably in the long term. Your seat post remains smooth and ready for use in just a few simple steps.
After every ride:
- Clean the shaft:
Wipe off dirt, dust and moisture from the moving part of the seat post with a soft cloth.
Weekly / every few rides:
- Check ease of movement:
Operate the seat post several times – if it doesn’t work smoothly, moisture or dirt may have got into the mechanism. - Control the saddle clamp:
Check that the screws are tight and retighten with a torque spanner if necessary.
Every 3-6 months (depending on use):
- Remove the seat post and clean the seat tube:
Remove old assembly grease and replace it sparingly to prevent corrosion. Otherwise, seat posts can possibly get stuck in the seat tube – removing them is then only possible with brute force, which can also irreparably damage the frame. - Check tension / cables:
For mechanically controlled models, retighten or replace the Bowden cable if necessary. - Check the smooth running of the mechanics:
In the case of mechanical control, check the remote lever and the Bowden cable for smooth running.
If required:
- Service of the cartridge:
Depending on the manufacturer and system, a full service (oil change, seal change) may be necessary after 100-200 hours of riding. Please observe the manufacturer's instructions or consult a specialist workshop.
Tip:
When not in use, store the bike as dry as possible and with the seat post extended. This protects the seals and adjustment system.