In this article, we’ll be discussing a Telescopic Mechanism by Giant Manufacturing , US publication 20240067289. The publication date is Feb 29^th, 2024 (leap) and the filing date is Aug. 28^th, 2023.

As large as Giant’s footprint is on the global bike trade, this is the first time I’ve written about them. Oddly enough, they don’t file much, and when the docs are finally published, the product has already been released. At least in the US.

Brief Summary (tl;dr)

In honor of the new and expensive Fox Neo dropper post (and maybe the new SRAM Preverb), which seems to be generally admonished by our fellow keyboard warriors, I wanted to bring the antithesis of Fox’s Neo.

Giant are working on a new dropper post that is simple, spring-loaded, and cable-actuated with only two positions: minimum and maximum. It aims to offer a more affordable alternative to traditional, costly seat posts while addressing issues like lack of feedback on seat post positions. The design is ideal for casual riders or commuters, requiring minimal maintenance. 

Background

The modern dropper post, which we all love (I think), uses a similar system to that of a telescopic suspension fork in that they use both an air chamber and fluid chambers for height control.

The air-side is the spring, biasing the seat upward. The fluid side, being incompressible, allows the rider to lock and unlock (for lack of better words) the seat post. The fluid side typically has at least two chambers separated by a valve. The system stays locked when the valve is closed, not allowing fluid to pass between the chambers.

When the rider wants to move the seat post, they flick a switch on the handlebar, the valve opens, and fluid can pass between chambers allowing the seat post to move freely. Actuation can be handled via a cable, fluid, or electronics.

At one point in time, there were a few companies trying to do this with a spring.

Intro

The concept of a spring-loaded dropper isn’t new, and you don’t need to tell me about them because I’m about to tell you.

My research suggests the Gravity Dropper was super early (maybe numero uno) with respect to the modern-dropper post using the telescoping design we see today. This was a spring-loaded system with a pin to set the height.

Another similar product is the e*thirteen TRS+ dropper from like ‘16/17. Based on this schematic, this particular dropper appears to be fairly similar to this new Giant dropper in this document.

What we’re looking at here from Giant is a reinvention of an older concept.

Why

Traditional seat posts, although flexible, are costly.

Although the user has a high degree of freedom of adjustment, the relative cost is too high.

Stopping (parking) the bike.

Through the adjustment of the height of parking, the user is able to lower the height when parking and thus improve safety with both feet touching the ground.

This one’s a stretch for me (but might be that I’m not exposed to this issue) but Giant also say the lack of feedback as to the position of the seat post can be an issue.

…the design does not show the user of the exact position for adjustment. As a result, the adjustment of height is not intuitive enough, and errors are likely to occur when the user makes adjustment between height for riding and height for parking.

And one more time, the price. Since they say this twice, I’m going to assume this new post would be relatively inexpensive.

…high price hinders most consumers from enjoying a safer riding experience.

What

FIG. 1B shows an exploded view of this new dropper. We want to focus on the cable 166 (purple), little spring 167 (blue), push block 165 (pink), balls 162 (red), collars 150a and 150b (green), and the big spring 180 (orange).

FIG. 2A shows a cross-section of this seat post in the fully extended position. The push block 165 is controlled by cable 166, and the push block is biased upward (to the right in the image) by the little spring 167.

Long story short, when the cable is pulled by the rider, the push block is pulled downward, allowing the balls to move freely in the open space (annular groove OG). So, now that the cable is pulled and the balls have moved inward, the post is unlocked. The rider can sit on the seat and lower it all the way down, release the cable actuation, and it’ll lock at the bottom of the seat post.

An animation is probably a better way to visualize this. This shows the unlocking sequence. We can see the cable pull, the push block move, and the balls move to release the seat post.

FIG. 2D shows the post in an intermediate position, so it’s not locked in any position and can move freely between the minimum and maximum positions. Remember, there is no locking position in this area between the collars.

FIG. 2E shows the post in the fully compressed position. The balls are now locked into the collar 150b. You can unlock it the same way as prior, and the big spring will bias the seat post upward and likely smack you in the nuts like the Specialized Command did to me on many occasions.

Conclusion

I had a friend a few years ago, my boy Dane, who sold me on his preference for droppers. The argument is that seat posts really only need three positions: max, min, and trail. Max for climbing, minimum downhill, and trail set at about 80% max for flat-land pedaling.  The infinitely adjustable seat post is just not necessary. Personally, I never need such granularity on a ride.

In support of the two-position system, I would love to see someone’s ride data plotting seat position over time. I’d take a guess that a dropper spends a huge majority of its time either fully extended or fully compressed. If that’s true, that would support the case that a two-position seat post is perfectly acceptable. I know Fox or SRAM have this data somewhere. All it takes is a small datalogger and a strong pot. Shit, a camera and stopwatch would work.

Speculating, but I’m fairly confident that the actual product would be heavier, while also being simpler, easier to service, and maybe more reliable.

My one primary question here is: how do the balls move inward? I can’t see a biasing mechanism, so are we just trusting they’ll move inward when the push block moves downward? If one of the four gets stuck, the whole post doesn’t work, right? Would the movement/vibration of the bike unseat the balls enough to move them inward?

As far as application, this would be perfect for the casual rider or the commuter. They’ve basically made a seat post for riding and for a stop light. That being said, if this thing is decently weighted and works as intended, I wouldn’t think twice about not using it, especially on my gravel bike. That dropper is only ever in max or min, anyway.

And it’s unlikely that this will take much service (which I’m just smitten about). Less service means more riding.