In this article, we’ll be discussing a [Flexible] Bicycle Seatpost by Canyon, US publication 20210061385. The publication date is March 4th, 2021 and the filing date is Aug. 27th, 2020. This patent has not been granted, yet.
This was released at the exact same time as the stem tube, so it appears Canyon are working hard on their race bike compliance and aerodynamic systems.
There was also a third patent for racing handlebars, but there’s just not enough content in that one to justify an entire article. The image to the left shows how the bar can be shaped, among other shape-items of note. How are they going to enforce this one? No idea.
Intro
Canyon are introducing an aerodynamic and flexible seatpost design for their road race bikes. The load-bearing portion of the seatpost is an S-shape, where the insertion portion sits forward of the exterior portion of the seat post. An aerodynamically shaped damper adheres to the front of the flexible portion of the seatpost. Then, an aerodynamic cap is attached to the front of the seatpost. In the end, it’ll look really similar to a current aero-seatpost, but the S-shape will provide the flex, and the cap provides improved aerodynamic properties. Pretty cool to see Canyon double-dipping with the same design.
Intended Novelty
The explicit intended novelty of this invention is the use of a damping element (bending area) and a support element (inside the seat tube), with the addition of an aerodynamically shaped element that at least partially encloses the bending area. This is a fairly vague statement, so I fully expect this to be rejected by the USPTO at least once because this has vague claims. The attorneys will then need to add some kind of limitation.
Why
Hot nasty badass speed, that’s why. And comfort. We gotta keep these riders comfy.
What
Figure 1 below shows the entire system in question. Bending member 24 provides the flex. Holding member 30 goes into the frame and is clamped from the back. And shaped element 14 contains the damping element.
Something I was concerned about was the stress (60 and 62) to the seat tube from the seatpost bending forces. It appears Canyon are addressing this already, but it still sounds unclear. Even with the clamp at the bottom of the seat post, there should still be some level of stress at area 60, right? I think Canyon are hoping this system only flexes forward, but what if a person is seated too far back? Will the seatpost bend backward and apply some level of stress to the seat tube at location 60?
…the… side view S-shaped design of the bicycle seatpost has the advantage that two contact and stress points occur on the frame. An upper stress point is at the upper frame end 60 and a lower stress point is at the lower end 62 of the saddle support… the clamping is carried out in this area
Figure 2 below shows the damping element 12 and the aerodynamic element 14. With this S-shaped design, you can’t have a bending element, only. Without something dampening the bending, the seatpost will just pogo-stick your ass, and that sounds worse than a rigid seatpost. So, Canyon have designed damping element 12.
The damping element 12 provides a level of support with a solid piece of (I’m assuming) elastomer, plastic, or rubber. Canyon state this piece may be glued to the seat post itself.
…a rear side 38 of damping element 12 facing towards front side 34 is connected particularly with its entire surface with front side 34, in particular by adhering… The deformation of damping element 12 is suppressed by the shell-shaped shaped element, so that the damping element is compressed or stretched. This leads to a destruction of energy and thus a damping.
Then we have shaped element 14, which is just a plastic cap for the damping element. Canyon have addressed the issue of the cap contacting the seat post by adding gap 52, so the cap won’t hit anything when the seatpost flexes
Figure 3 shows a cross-section of the clamping area. A screw, with a clamping element 54, applies pressure to the bottom portion of the seatpost 30. They’re very clear that the seatpost does not fill the seat tube.
So, what about the seat height? Canyon aren’t super clear about this, but by the powers of intuition vested in me, I’m pretty sure the area 28, below the seat tube in FIG.1, is where the seatpost will continue to settle into. Take a look at the shape of the bottom of the tube, to the right. In short, the images provided by this patent show the seatpost in the highest position, and the seatpost can go further into the frame.
Conclusion
Again, the stresses to the seat tube are still a concern to me, but if Canyon can solve that, then there shouldn’t be many problems with this design.
It’s very rare to see three patents come out at the exact same time for the same concept. I hope all the other manufacturers are paying attention to how much Canyon are investing in compliance and aerodynamics in the same package. Hopefully, this thing doesn’t result in another ‘stop ride’ situation.
Looks like Canyon is already seeing a high failure rate on these seatposts. It’s discussed in the video below:
https://www.youtube.com/watch?v=Hp8IBAQYggE
I feel Peak Torque may have misinterpreted the intent of the design: he believes there is supposed to be clearance between the top, rear of the seat-tube and the post, allowing for free movement. I doubt this is the design intent, which is supported by the patent verbiage. It seems the design intent is just to allow greater flex via a “three point bend” movement with greater beam length.
In any case, the fretting at Point 60 seems to be a problem Canyon needs to address. Maybe bond a thin layer of steel or a consumable polymer bushing … something simple like that.