PRESS RELEASE: Fraserwerk
Faserwerk integrates a viscoelastic damping layer into the Rockstock carbon handlebar that reduces vibrations by a significant amount. The 189g light, 800mm wide handelbar withstands the most stringent testing.
Faserwerk is a new component brand of kreuz+quer, the company behind bike brand ARC8 and bicycle.engineering. Thanks to an investment in a manufacturing facility in Taiwan, we are in full control over all aspects of the product, be it design, layup, production process, quality control or testing. The first MTB product to come out of our new facility is the Rockstock handlebar.
The Rockstock is not only our first handlebar, but the first carbon handlebar on the market to incorporate a viscoelastic layer, reducing vibrations. But let's look at the Rockstock's numbers first:
• 800mm wide
• 20mm rise
• 9° back sweep
• 6° up sweep
• 31.8mm clamp diameter
• 189 grams
• 199 CHF/EUR/USD
We think that is not bad at all, before even talking about the damping feature.Design
Before we can get into the fascinating world of layup development and damping, we have to talk about the design. Design of a handlebar seems easy, but it is not. We went for 6° up sweep and 9° back sweep because that feels the most natural with handlebars only getting wider. 800mm seems the reasonable upper limit, but there is enough space for the controls to cut it down do 740 mm.
We tested a lot of different designs, and there were two consistent findings in all that testing: Having a smooth transition from the 22.2 mm diameter at the grips to the stem clamping are is key for a light and strong handlebar. And we basically could not find an advantage in using a 35mm clamp. 31.8 mm would end up being lighter and stronger, and we could not find anyone wishing for a stiffer carbon handlebar. So handlebar design may look very simple, but as testing of other designs showed, it is still a key element for a high perfomance product.Layup Development
Layup development started with a simple FEA, done in Femap. Using a constant wall thickness, we can identify stress distribution and major stress directions.
Based on this, we can start designing our laminate ply by ply in Laminate Tools.
For each ply, we see distortions of the ply we have to expect when wrapping it around the mandrel, resulting fiber directions and warnings if there are areas with too much distortion, which could result in wrinkles or gaps in between fibers. This depends on where you start to apply your ply and in which sequence you wrap it, so we can set that in Laminate Tools. Also, if we force a reinforcement to follow a certain path, Laminate Tools allows us to simulate that, as you can see in th picture below. Such simulations would not be possible in FEA without a draping simulation software like Laminate Tools.
After we have built the layup, we can analyze different aspects of it, like total weight, number of plies, thickness distribution or what fiber directions are present at a certain location of the product.
This layup can then be directly simulated in FEA, with a lot of tools to look into the results a traditional FEA could not offer. The reserve factor plot quickly shows how far we are from an appropriate strength.
Navigating to an element that fails and creating a stress/failure index plot through the laminate there shows us which layers carry load, and which layers fail. That is not necessarily the same, as a layer that does not carry a lot of load can still fail due to an unsuitable fiber direction. It is also more information than we can get from testing on an actual product. So if we have a failure in testing, going back to Laminate Tools helps us to better understand the failure.
After identifying the reason for failure, modifying the layup and simulating it is done within minutes, a vast difference compared to the hours of work to create a new real sample. So as impressive as the actual numbers of the Rockstock are, it only took 3 iterations of prototypes to get there.Viscoelastic Damping
When it comes to carbon bars, there was always one talking point: a lack of comfort. This is why started to look into options to increase damping. We tested various materials and methods. Finally we found one that significantly increases damping without lessening the strength and only adding 5 grams in weight. A viscoelastic layer is embedded in the laminate.
How does a viscoelastic layer work?
As with all damping, a viscoelastic layer transforms kinetic energy into heat. To go more into detail, when the laminate deforms under load, interlaminar shear deforms the viscoelastic layer. Instead of bouncing back like an undamped spring, internal friction transfoms this work into heat. So we had to identify areas with high interlaminar shear to make best use of the damping material. Thankfully, that was easy since we already had the FEA model where we could identify these areas.
So, how does that translate to what the Rockstock makes different than a carbon bar without viscoelastic damping? If you hit something, your handlebar deflects and bounces back. Without damping, it would now keep swinging forever. Luckily, there is natural damping in a carbon handlebar. With the viscoelastic layer, we achieved double that damping. While double may sound like double as good, the actual effect is much bigger. Look at the diagram below which shows the response to an impact. With viscoelasic damping (black curve), the vibrations caused by the impact have basically died off 0.3 seconds after the impact, while the sample purely made by carbon (red curve) is still visibly swinging after one second.Enhanced Control Over Your Bike
Now that we went through the physics of damping, what does that mean for your riding? Imagine you hit something really hard while riding. Your handlebar will deflect significantly, more than 20 mm in our impact testing. Which is good, because a) it smooths out your ride and b) it means your handlebar does not break. But what follows is less ideal: without damping, your handlebar keeps wobbling for some time. A wobbling stick between your hands and your bike is certainly not what you want. So the faster we can stop it from wobbling, the more precise you can handle your bike. Remember the diagram above: With viscoelastic damping, the wobbling basically disappeared within 0.3 seconds. Without it is still wobbling one second after impact. If you are riding at 36 km/h that means you covered 10 m of trail with less than ideal control of your bike.Comfort and Health
Excessive vibrations can cause discomfort and even injuries, as Lewis Kirkwood greatly explained in this interview
. Putting your hand on the handlebar will add damping similarly to what our viscoelastic layer does, but what does that mean? Your body needs to absorb the energy stored in the handlebar. This can lead to effects like arm pump, reduced grip strength, numbness or inflammations. So by adding damping into your handlebar, your riding gets more enjoyable, and you can do that extra run while your friends need to give their arms a rest.Testing
ISO does not specify any impact testing for a MTB handlebar, which seems quite irresponsible. There is however a test for BMX, where a weight of 10 kg drops from 500 mm height onto one end of the handlebar. That is quite a stringent test, but with the Rockstock, we passed double that requirement despite the handlebar only weighing 189 grams.Availability
The Rockstock is in stock and can be purchased through the ARC8 website
or selected dealers.
Its not the same.
You don't crank a motorcycle
Infinite stiffness is great for pedaling, pulling up on one side down on the other.
Infinite stiffness may help steering feel, maybe.
Verticle flex would help smooth hard landings (one up bars are designed for this)
The vibrations aren't just from chassis inputs, your creating them by landing on the bars with your body weight as well.
Its like ringing a bell.
Check out spanks white paper about developing the vibrocore bars.
More flex means that they can move further while vibrating.
On a motorcycle they are trying to get rid of engine vibes mostly. Also you often don't yank the bars quite the same..... using the throttle instead and holding the bike with legs.
Which leads to my last point, why do people who write "white papers" always come up with rubbish?
No they don't claim to get rid of vibrations but to shift the natural frequency of the bars to a less irritating/higher frequency.
Also yes they should have the weight of a hand to better simulate real conditions
So great to see a brand doing what they found to be the best, based on technical aspects and data analysis, and not what they think people would like to buy.
That said, the IRD Manticor handlebar I have is 35mm and a VERY comfortable carbon layup. Just because its’ 35mm doesn’t mean it isn’t going to be comfortable.
- Say again?
I have been using the SQ Lab bars for a couple of years now. This 30X bar has 45mm rise, 12º backsweep, and is 780mm wide (790mm with grips). I use this because the extra backsweep is more comfortable and in one week cured some tendonitis that was building up in my arms for a few years. I usually use the 16º version...
I'll second that the 16 degree bar solved some terrible wrist pain I was having when riding daily.
On Rune I use 777mm Spank Spide EVO handlebar so I didn't bother trimming this XLC handlebar and I like them a bit more than Spike. They have sort of natural feeling and ride is more comfortable.
I have a rule that saddle must not be higher than handlebar. If it is, then the bike is of wrong size, wrong geometry or cockpit is worng. I think that even today with "modern" geometry 99% of riders have their handlebar low or too low, below the saddle height.
XLS for crazy 25eur
Would be good to see some back to back, real world vibration testing with some different bars.
> Putting your hand on the handlebar will add damping similarly to what our viscoelastic layer does, but what does that mean?
These don't track. If your arms are damping (they are), you're not going seconds at a time with a vibrating bar. There's an argument for more flex (reducing peak G) and more bar damping (reducing pump), but not for 'less than ideal control' from lack of bar damping if your arms are doing the same work.
If you look at their time-response graph, their bars also reduce the amplitude of the force.
Not sure how much all this translates to ride feel or quality but it's interesting.
I'm actually more interested in this technology on the road side. There are a lot of light carbon leaf-spring designs that could benefit from more damping (Canyon's VLCS, Trek's IsoSpeed, various fork designs, etc.).
I have a Trek Boone CX and it does have a little piece of rubber/elastomer around the isospeed pivot. If I am being totally honest though I can’t tell how much of a difference the isospeed system makes as a whole. It’s probably more of a cumulative affect as opposed to something that be acutely felt. More damping may help but there not a lot of movement there to begin with.
I put one on my seatpost once to see if the seatpost or the seat stays flexed more on an old hardtail of mine
Same thing, right?
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