Back in 2016, Funn launched the external routing version of UpDown dropper post that was based on an Internal Floating Piston (IFP) cartridge unit. Almost all of cartridge-based dropper posts on the market still use the IFP cartridge. Advantages of using IFP cartridge is lower cost and the seatpost can be serviced with ease. However, all IFP cartridges have a tendency to draw air into hydraulic chamber over time, resulting in seatpost sag. This problem can only be cured with cartridge replacement. The all-new UpDown adjustable seatpost utilizes a revolutionary Twin Tube Cartridge system that mechanically resets and restores oil and air locations within the cartridge whilst you use it, eradicating saddle sag issues and retaining all the benefits of a cartridge dropper post.
Here is how the Twin Tube cartridge works in more detail:
The cartridge has an outer and inner tube that contains compressed air and hydraulic oil. When the actuator is in a closed position, the seatpost is locked. At this point, the hydraulic oil contained in the inner chamber supports the rider’s weight.
When the actuator opens and dropper compresses, oil flows from the inner chamber to outer chamber, and compressed air enters the upper part of the inner chamber. At full compression, the piston respells both hydraulic oil and unwanted air from the inner tube.
When cartridge rebounds from full compression, compressed air pushes the piston shaft upwards. Only the hydraulic oil gets sucked into the inner chamber. This way the cartridge can effectively reallocate both air and oil back to its proper designated locations in the system. This ability to self-restore and refresh means less maintenance and lasting adjustability and performance.
For the new UpDown dropper post, we spent a vast amount of time and attention to ensure excellence and consistency every step of the way from design, development to production.
Working in closely with our automotive grade cartridge partner, we made sure that the new UpDown passes the most rigorous tests to ensure performance and quality.
In the development stage, data is gathered on a dynamometer to check downward force required to compress the cartridge and rebound force. The goal is to fine tune and achieve the perfect balance between rebound and compression force for best usability.
Lab tests simulate field usage by way of actuation cycle test over 30,000 cycles. When testing is complete, dynamometer results confirm no rebound force degradation and zero saddle sag.
The UpDown dropper post was developed to withstand the weight of a plus-size rider and make sure the dropper post conforms to the ISO4210 standard. In a max load test, the dropper post held up more than 200 kg easily.
Another feature of the UpDown dropper is the revised 4-way trigger lever. The new lever has a longer leverage and infinite angle adjustment. This lever can be installed with the cable head at the lever end or under the dropper. It can also be integrated with SRAM Matchmaker clamp.
- One piece forged 7050 alloy inner tube with hard anodized coating
- 2-bolt type clamping
- 4-way mount remote lever
- Diameter: 30.9mm / 31.6mm
- Travel: 125mm / 150mm
- Weight: 550g (125mm seatpost), 50g lever
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