In this article, we’ll be discussing a Handlebar Stem and Handlebar Stem System by Canyon GmbH, US publication 20200354011. The publication date is Nov. 12th, 2020 and the filing date is May 6th, 2020.
I’m having a hard time figuring out if this patent has been publicly disclosed. I don’t think it has, so I’m going to write this article about it. This is a very short patent, so this will be a shorter article.
Brief Summary (tl;dr)
Canyon have introduced a flexible stem and handlebar system for road biking applications. The stem contains a stem tube that is integrally mounted to the handlebars. The stem tube has an oval shape and is inserted into the steerer tube and is bolted to the fork to hold the stem tube in place. The top of the fork area has a cavity that give the stem tube room to bend. The oval shape of the stem tube provides the ability to bend in a longitudinal direction but not in a lateral direction. Therefore, as the rider rides over rough terrain, the handlebars have a small level of compliance, but can still steer without a bending reaction.
If you’ve been on any long road or gravel ride, you’ll know how tough it can be on the hands, arms, and back. Like many other manufacturers these days, Canyon are trying to make a more compliant, comfortable road bike for long distance riding. Trek have their IsoSpeed and Specialized have their Future Shock, among others. These have been very successful ideas, as more manufacturers come up with their own in house designs. One thing I learned in my racing days is that if there is a convergence of an idea, then the idea is probably correct. We’re seeing a convergence of this idea, meaning it probably works.
In this article, we’re talking about handlebar compliance on road bikes. From what I can tell, Canyon haven’t released much in this field. They have their VCLS (vErtIcAl CoMpliAnCe, lAteRal sTiFfnEsS) system, which appears to incorporate seat stays (maybe?) and a seat post, but have nothing in the realm of a handlebar system.
The intended novelty of this invention is a non-circular cross section of a stem tube, with a cavity at the top of the fork to allow for bending of the stem tube. The non-circular cross section allows for the handlebar and stem to bend in one direction and not in the other direction. In this case, the bar and stem can bend in a fore/aft direction and not in a left/right direction.
Canyon state the reason they’re doing this is:
… impacts introduced to the bicycle fork by unevenness in the road surface can be absorbed and are only transmitted to a smaller extent to the bicycle handlebar and thus to the cyclist’s wrists. Thus, the riding comfort is significantly improved, in particular when connecting the handlebar stem according to the invention to an unsprung bicycle fork as usually provided for racing bicycles.
Canyon are patenting a non-circular stem tube that goes into the steerer tub and into the fork, from the handlebar. There is a cavity inside the upper fork to allow for bending of the stem tube. The cross section of the stem tube
…has a smaller dimension in the longitudinal direction of the main element, that is in the mounted state in the direction of travel, than transverse to the longitudinal direction. In particular, the cross-section of the handlebar stem tube is of transverse oval shape.
Figure 1 shows a cross section of the middle of a bike with the proposed system installed. As the rider applies a force, whether it be a weighted body force or a reactionary road force, there is a resultant flex of the stem tube inside the steerer tube. Canyon do not state any flex numbers or supporting data, but conceptually, this should work. Realistically, I have no idea if it will work in the real world. It also looks like it would not be fun to service unless Canyon do a little tweaking to their steerer tube area.
This is an extremely simple idea. Implementation is a different story.
The following are important pieces:
The stem tube is attached to the handlebars via a clamp or integrally mounted. We will assume they’re integral for ease of explanation. Either way, they move as one piece. The stem tube is then slid into the steerer tube where the stem tube is inserted into an opening of a ‘lower area’. Canyon do not explicitly state what the lower area actually is, but I would assume it’s the top of the fork. The stem is then clamped or bolted in place in the steerer tube. There is a spacer located at the top of the steerer tube to keep the stem tube in place and to provide for a pivot location, to allow the stem tube to bend. Canyon state that it is preferred for the spacers to be made of an elastic material.
I’m not entirely sure how they’re going to bolt this in place inside the steerer tube, unless there is a hole on the front side of the steerer tube to allow a bolt through.
Figure 2 shows a cross section of the stem tube 44 and the cavity 46 inside the fork. The arrows 36 represent the direction the bike is traveling. This is a simple representation of what the stem tube may look like inside the cavity. Notice the large volume available for the stem tube to move around.
A lingering question I have with this is; do you need a special fork for this to work? I haven’t taken apart a road bike in a while, but I don’t remember a road fork being able to have something inserted into it like this. Also, where is the preload adjustment? If the stem tube is bolted into place, how can one make sure the fork is tight and right? Canyon aren’t clear about much in this publication.
Well that’s it. Pretty simple invention. Thanks for reading. Email me with any questions about this one.