Norco Factory Team Mechanic Lewis Kirkwood Thinks Mountain Biking Could be Giving us Bad Vibrations
Lewis Kirkwood, the Norco Factory Team mechanic, conducted the study as part of his PhD.
We’re all used to the ‘mountain bike claw’ at the end of a long day of riding as we pry our semi-paralyzed hands from the grips. The feeling of being beaten up after a day of bike park battery is part and parcel of modern mountain biking, but just how much vibration are we getting through our handlebars? And is that safe for us in the long run?
A recent study from Edinburgh Napier University suggests that mountain bikers are experiencing more intense vibrations than a construction worker who has spent a day on a jackhammer. The study was carried out by Norco Factory Team mechanic, Lewis Kirkwood, as part of his Ph.D. He fitted accelerometers to the bars of two top-ten riders' bikes at a round of the Scottish Enduro Series and the British Championships. These are tracks that have hosted EWS rounds in the past and represent a typical, elite-level enduro race.
The data returned suggested that vibration levels the mountain bikers were experiencing exceeded the safe recommended levels according to ISO standards. ISO is a body that creates standards covering 164 countries with the goal of ensuring products and services are safe, reliable and of good quality. ISO 5349 - 1:2001, which monitors human exposure to hand-transmitted vibration, caps vibrations at 5.0 ms^-2, but Lewis found mean values of 5.84ms^-2 on the riders he studied, as well as values topping out at 6.61ms^-2.
Before you panic, we don't yet know if those standards are relevant to mountain biking. "Just because these numbers are over the arbitrary value that we label as being bad doesn't mean that the riders can't handle it," says Kirkwood. "We’ve still got a long way to go but I think it is important to quantify it." In the workplace, exposure to vibration has been linked it to musculoskeletal, neuromuscular, vascular and other types of pathologies such as hand-arm vibration syndrome.
We caught up with Lewis to talk about how the study came about, what it might mean for everyday riders, and how we can limit the vibrations we experience when riding.
How did this study first come about?
Lewis: We started out by looking at the physiological demands of enduro racing. We had 9 elite racers for a year, and one of the ways of measuring the demands of racing was using Catapults. Catapults are pretty basic GPS units that can start to look at braking and the distribution of speed on tracks, and they can tell you a lot about where the fast guys make their time.
With those, you can measure whole-body vibration and we saw some quite high values but the equipment didn't meet the specifications to measure at the ISO standard. This led us on to realising that we needed to measure vibration in accordance with international guidelines to fit it in with all the other research out there. At the moment, mountain biking is on its own path with how you measure things so we had to bring it back in line with the standard, it had to fit in somewhere.
 | My professor did a study at Fort William and you can lose around about 30% grip strength in one top to bottom run. |
Where do these standards come from? What industries are experiencing the most vibrations?
Lewis: Construction, people that spend all day on jackhammers, lumberjacks, and joiners. The reason these guidelines are in place is that they're seeing hand arm vibration syndrome, an irreversible pathology. You can get white fingers syndrome, peripheral circulation, and nervous problems and musculoskeletal problems. So, there's a reason those guidelines are in place but we still don't know very much about how they come about and it's different for everyone. Some people can experience more vibration and be fine and some people can experience less vibration and not be ok. It's still early days but you have to put a number on it at some point.
Are there other reasons vibrations are important for mountain bikers?
Lewis: The more vibration you expose yourself to, eventually it's going to limit your grip strength. Vibration stimulates muscle and it makes the muscle tense, which is why you get arm pump because your muscle doesn't relax and it cuts off the blood flow.
My director of studies, Professor Geraint Florida-James, did a study at Fort William and you can lose around about 30% grip strength in one run top to bottom. Eventually, you'll hit a big hole and you can't hold on or you lose your posture. It's all energy; it has to be dissipated somewhere before it gets to your head. The more you can limit it at your hands, the faster you’re going to go but keeping that control and performance is the key part.
Lewis: We also had models for how much training the guys were doing and mountain bikers, going by heart rate, were doing roughly half of what the road riders were but they were still getting the same improvements in physiological parameters. You have to provide the same stimulus to get the same outcome, so we were obviously missing half the measurements. In mountain biking there's a lot more involved in terms of vibration, shocks, riding through holes and all of that stuff. That was something that pointed us towards vibration being a missing training load in mountain biking.
Should elite and everyday mountain bikers be worried about vibrations?
Lewis: Well, we don't want to cause panic with anyone and actually I've only got a hardtail so I don't want the warriors to come and eat me up for being some sort of fear monger, but it's concerning. It's at the point where we don't know what happens if we keep doing this for years and years. We don’t have mountain bikers that have grown really old yet.
As I grow up, I want to be healthy but the consideration for me is that I'm going to ride mountain bikes whether or not it's going to be harmful because I like riding bikes. We believe there are ways of optimising the design of components such as handlebars, grips or even gloves, tyres and spokes, and if we can look at ways to minimize vibration while still keeping the performance then that has to be a good thing.
Just because these numbers are over the arbitrary value that we label as being bad doesn't mean that the riders can't handle it. We’ve still got a long way to go but I think it is important to quantify it because if you can't do it reliably and in a valid way then how do you know if one handlebar is better than the other?
So what's next for you and this study?
Lewis: Professor Florida-James has just secured £19 million funding for an Innovation Centre and a bike park in Innerleithen with Edinburgh Napier University and with the Mountain Bike Centre of Scotland, which is a pretty massive deal.
This is just scratching the surface with handlebar vibration. This was to prove that we could do it, then with the Innovation Centre we can test different things. So if you had a component manufacturer with different layups of carbon handlebars and they wanted to know which was better in the field then we can put an actual number on it to reliably measure it. Then you go into seatposts, and frame material and spoke tension and that's what I want to do more of.
Lewis knows a thing or two about vibrations as a hardtail rider.
Lewis: It gets really interesting when you can measure it and then measure the response from the body too. At Napier, we have a big physiology department where we can take blood from people so we can link up vibrations doses and changes in the blood to see if there is a relationship with things like osteo-arthritis and all the other nasty pathologies that potentially go with vibration exposure. It has opened up more questions than it's answered at the moment!
The key thing I wanted to say is I'm not trying to scare people away from riding bikes by any means, it's just something that we've realised is potentially going to be an issue and to address it. You see products coming out all the time that flex for comfort and then other times it's all stiffness and strength. Ultimately we can measure these things and ultimately we would want to work with companies to develop such products to find the best balance.
The full study can be found here.
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191 Comments
I was suffering from the first stages of white finger from poorly damped chainsaws after years in tree surgery and forestry, but switching to Spank vibrocore bars and larger diameter Ergon grips has made numbness during riding almost non-existent.
You also have vibration disease which can impact peripheral nerves, blood vessels (Reynaud's Syndrome), and even bone/joints.
Again these have been linked to jobs with much higher exposure levels and durations much longer than what we get through mountain biking.
At first ride you won’t notice the difference between the carbon bars and vibrocore. But for best results is to ride with one setup for a month, then change back to your old set up. You need to do this because you already programmed your mind into thinking one way is how it should feel.
Another think that people do not account for is bar width and grip diameter. I bummed up to the largest grip diameter and went from 800mm to 790mm.
I've been riding mountain bikes, starting with BMX, for forty-five years. As a 50+ guy I will tell all you young uns that a time will come when it becomes harder to hold onto those grips. No matter how strong you are, no matter how much you train, you will become less virile.
To compensate I am running coils, longer travel, flats, and thick 9mm Red Monkey grips.
And I still get at it, just take longer periods between poundings
edit - just looked and they're single ply vs dual ply.
I know i'm late just wondering
I don't really get arm pump, but riding rough terrain like bikeparks with braking bumps will cause my fingers to seize up. It's like they become frozen in place, it's insanely painful to get them moving again and eventually my fingers even become painful to the touch, almost like I've bruised the bones. It doesn't seem related to how tightly I'm squeezing the bars, either, but the effects can last into the next day.
I've been considering those Revolution grips with suspension but they're an investment for sure.
You need to find some more positivity in life so you don't come off as angry and dumb for no reason
Mark the position of your brakes and change only one of them. After half a day of park, you check if you feel a difference between left and right hand pain.
I have not yet ridden in a bikepark this year, and I'm still hoping to find a solution that reduce the pain. I remember people were saying that the OURY grips were the best to dampen vibrations. I have not tried them yet.
I suffered from quite severe arm pump and thought you guys might like to know how I have improved it.
My first recommendation would be to get yourself checked by a hand ortho to discard you have medical issues like carpal tunnel, and also as a disclaimer, whatever I say is not to be taken as medical advice.
First of all, severe hand pump has a medical name, it's called Chronic Exertional Compartment Syndrome in the Forearm. What happens very simply speaking is the muscle groups of the forearm swell up beyond the fascia that sorrounds them (fascia is a fibrotic inelastic tissue that sorrounds muscle groups in the body), this increases pressure in the forearm which prevents circulation getting to both the nerves and the muscles, resulting in loss of strength, sensibility and pain. There are two solutions to the problem... you either stretch the fascia allowing more space for the swelling of the muscle, or you cut it surgicaly (if only tried the first one, but from what I've read surgical minimaly invasive resolution of the problem results in immediate resolution of the problem from reports both on professional dirt motocross and rowers).
So, what have I done to stretch the fascia (known as myofascial release, youtube it).
I copied the idea of a device sold for motorbikers (4arm-strong.com) and improved it a little. I actually bought the device and it helps a lot. Watch the tutorial video to get an idea of the concepts (www.youtube.com/watch?v=x2SHY0l35x0)
This is what I built www.pinkbike.com/photo/17574271
It's a lacrosse ball cut in half, using a crank extractor tool kept in place by a vice, so that it prevents the ball from moving forward when I do the myofascial release exercises. Could also nail it to a table I guess.
I do two exercises:
1.- www.pinkbike.com/photo/17574273
Stretch your elbow and flect your hand and fingers, look for the thickest part of the muscle group on the back of your forearm (it's a little to the lateral side in that position). Press it as much as you can on the ball while at the same time maintaining a forward push on the ball, and at the same time maintening the flex on hands and fingers. Hold for 20 seconds, repeat 3 times.
2.- www.pinkbike.com/photo/17574275
Same thing but working on the other side of the forearm. Look for the thickest muscle group (a little on the medial side on that position) extend hand and fingers (help yourself with the other hand), press the ball on the muscle group while pushing. Maintain for 20 seconds repeat 3 times.
If you find your forearm sliding too much on the ball clean both with alcohol.
Afterwards I use a complete (not cut in half) lacrosse ball, and press on those muscle groups and following their direction while moving the ball against a table or wall. Start easily, too hard at the beginning with any of these exercises could irritate the nerves more.
Other recommendations.
DONT TRAIN FOREARM STRENGTH on the gym. Train Pecs arms and back, so that they handle the biggest part of the load, use forearm only as stabilizer to your arm and pec exercises. Consciously relax your hands and grip when riding.
Gear improvements: coil the shock it if you can, 29" if you can, vorsprung luftkappe if you cant coil it, and re-shim it to your weight and riding stile (vorspung, push, avalanche customize the damper side of shocks). Rev Grips, Oneup components handlebar.
edit: I forgot to mention, use brakes that need the less force possible both in the free stroke and while squeezing, and put the levers in the Yoan Barelli position because it relaxes the posterior muscle group of the forearm wich is the one that I've found to be more stressed. Don't down vote me on branding but unfortunately I've found shimanos fit better this description, same goes with 29" wheel size
I run virtually flat brake levers, and I use the ODI rogue grips, but neither has helped too much. Maybe time to try a vibrocore bar.
You can’t get shaken by what you can’t feel.
In some areas vibration is used as a stimulus, for example with stem cells for cartilage growing, but it´s all about the right parameters. To little stimulus and nothing happens, to much and the cells die.
Just like everywhere else - it´s about finding the right balance.
I'd just like to point out though that the 5m/s-2 acceleration is quite low for typical working conditions. Construction works use tools like hammer scabblers or road breaks that can be in the region of 20m/s-2 although by all means far less exposure.
Since hand arm vibration syndrome is an accumulative effect a life long multiple ride a week MTB'r is at higher risk than your average joe. However, the actual time descending on a typical day (for myself at least) is around 25mins/30mins on a 4hr ride for example, which according to the H&S exec (See below) @ ~6m/s-2 you would need to have around 45mins of descending to reach the exposure action value (minimum to hve lasting effects). There is an argument that on a day with lots of bike park laps and uplift you can get well above this 45mins descend time but even still you would be nowhere near the maximum limiting exposure time of 4hours @ 6m/s-2.
I think this is something we need to be aware of and certainly advances in technology will help us, but unless you are actively working with these kinds of tools as an occupation, the additional vibrations from riding shouldn't be anything to worry about from a long term health stand point.
Table 2 Simple 'exposure points' system
Tool vibration (m/s2) 3 4 5 6 7 10 12 15
Points per hour (approximate) 20 30 50 70 100 200 300 450
100 points per day = exposure action value (EAV)
400 points per day = exposure limit value (ELV)
Source: I'm a civil engineer and www.hse.gov.uk/vibration/hav/advicetoemployers/assessrisks.htm
Sort of missing part of the point. I feel like the larger point is the possible nerve damage from vibration. Hes gone thought the dosage math to show that while the levels of vibration could be dangerous for longer rides but likely most riders aren't going to see issues. Id be curious to see where gravel riders end up on this with their rigid bikes. Id think they'd be in more danger than your average rider plowing your average chunder.
"The more vibration you expose yourself to, eventually it's going to limit your grip strength. Vibration stimulates muscle and it makes the muscle tense, which is why you get arm pump because your muscle doesn't relax and it cuts off the blood flow.
My director of studies, Professor Geraint Florida-James, did a study at Fort William and you can lose around about 30% grip strength in one run top to bottom. Eventually, you'll hit a big hole and you can't hold on or you lose your posture. It's all energy; it has to be dissipated somewhere before it gets to your head. The more you can limit it at your hands, the faster you’re going to go but keeping that control and performance is the key part."
Interesting research though and I look forward to following how it develops.
I have since built a new DH bike with an air sprung fork instead of the coil i was previous using. being able to adjust the air pressure and fine tune it seems to have helped quite a bit but i did experience my grip issue at the end of the 2 day ride at MCBP NJ. It didnt happen as quickly as the year previous but it did eventually happen. I dont believe my brake levers are set up incorrectly, i do believe having a more fine tune-able fork has helped me quite a bit.
I have not experienced it riding any XC or DJ type stuff.
On another note: it's not always the vibration size that matters, it's how you use it
Oddly i very rarely get arm pump while riding. I used to when i rode bent and very stictiony 888's. Got better forks however and it went away. Even on loooong rough alpine descents.
Other variables are that I use push on grips and coil springs at both ends. On a recent riding holiday i noticed that the guys on air springs spent a lot more time complaining of arm pump/hand pain. Not exactly a scientific test though...
f*ck. i was gong to ask my doctor what was up w/ my right hand/forearm. not excited to see the word "irreversable" there. Looks like i need to invest in some super vibration-reducing grips if want to keep riding and try not to make this worse
Thats an impressive grant the supervisor got.
It's not very often years are spent researching something for someone's career where there is nothing so say or publish at the end of it.
How much unpublishable data (doesn't work with the theory) was collected to end up with the required amount of published data to meet a chosen theory is a question I often ask myself when I read 'latest research shows..' type articles across all media.
Classic example being the guy that invented the glue for post it notes. That was supposed to be super glue. It was still useful.
This is a bit of an oversimplification. There is a big problem in academia where negative results are not seen as publishable because they do not add anything new to our collective understanding of a subject. In theory researchers should only be motivated by finding the truth about something, but in reality there are financial incentives to find exciting new results, and negative results are not exciting (even though they might be informative). Researchers may then be motivated to produce more publishable findings by questionable means (e.g., looking for correlations between dozens of variables, p-hacking, etc).
Also, scientists don't prove or disprove a hypothesis. If they find an effect they reject the null hypothesis (sort of a baseline assumption that there is no effect). That is, they conclude that the null hypothesis is not representative of reality (though, the accuracy of this conclusion depends on the quality of the research). They then offer the alternative hypothesis as a possible explanation about what is happening, and it should be accompanied by some kind of rationale. They DO NOT ever prove the alternative hypothesis. That is just not how hypothesis testing works.
Thus is the history of medicine, so what can you do about it...
Its such a good vibration
Its such a sweet sensation!
www.ourygrips.com/mountain-grips
We should be friends.
LoL Really? LoL I don't think you are being serious. I think you are fear mongering and ensuring you get good grants.
Hans Rey is still riding MTBs. I think Tinker Juarez still competes in endurance/ultra endurance racing. There's 2 names real quick. I personally have been riding on/off since late '80s.
Hope you put those £19m to good use.
I've been an automotive service tech/labourer all my life I'm pretty damn familiar with vibrations.
So no I’m not trolling. I’m just pointing out how flawed your pints are when it comes to how actual scientific studies are performed.
Go learn to read.
And if the vibrations caused by mtbiking are affecting one person's health, chances are this person will stop ridding before to get old… So taking few examples that still ride is already creating a bias.
Have a cookie.
Adios!
And no 30 years is not enough time to know the effects of the vibrations
They're talking about pro racers
I have a weird feeling that you aren't going half as fast as those guys (and girls) and probably have had less vibrations then them
Maybe when you're 70 get back to us and tell us we're wrong but for now we don't care
It's like anti vaxxers: no matter how much proof you give against them they only believe the stuff that supports them