Article about mitigation of whole body vibrations

15 replies · 449 views

Jumbo
123 posts
#1Feb 17, 2021, 8:24 AM
Saw this article this morning and thought it was really interesting:
https://cyclingtips.com/2021/02/rough-ride-whole-body-vibrations-might-be-worse-for-you-than-you-think/
Basically, they found that seatposts make little difference, and cyclists get a level of vibration that's kind of bad for your back. And maybe tires can help.
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Shaun McNally
112 posts
#2Feb 17, 2021, 11:28 AM
I thought it interesting that the things they said would work.....Thudbuster seat post, Specialized future shock, or the Trek isospeed decoupler all come at "significant weight penalty" and pretty much rendered them out of the picture in their eyes.

I've got a Checkpoint with the isospeed, and I can tell a difference....at least I could when I first started riding it, now I'm use to it.
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stu
646 posts
#3Feb 17, 2021, 3:22 PMedited
As in other experiments a negative result isn't a bad thing. In this case I could use it to avoid spending a lot on an improvement of marginal or unmeasurable effectiveness.

I'd like to see a follow-up starting with large, obvious changes like suspension then moving to more subtle refinements like wide tires, sprung stems, and sprung seastposts then on to cushioning in saddles, bar tape, and clothing. That would of course require more resources and time but would provide a clearer picture of benefits vs. costs. Starting with the obvious should at least reveal something which can reduce vibrations.

Another application: https://www.dsta.gov.sg/docs/default-source/dsta-about/reducing-vibration-in-armoured-tracked-vehicles.pdf?sfvrsn=2
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ccand51997
265 posts
#4Feb 17, 2021, 8:59 PM
Shaun wrote:I thought it interesting that the things they said would work.....Thudbuster seat post, Specialized future shock, or the Trek isospeed decoupler all come at "significant weight penalty" and pretty much rendered them out of the picture in their eyes.

There are a lot of cycling inovations that die on the vine because of the cycling cultural obsession with weight. They should be worried about speed but that is harder to quantify and can't be hung on a scale to impress your friends. This past summer, I tried my first dual-suspension bike (it is my 'gravel' bike) and was shocked how much better it was. I don't enjoy getting rattled but I used to figure 'that was just how it it had to be." I mostly built it for a couple of races I do that have some very rough sections, but then I found that I liked it everywhere. Then I found that I could ride the aerobars offroad when the wind kicked up. Now it is my favorite bike I have ever owned because it mitigates vibration and bumps.
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ccand51997
265 posts
#5Feb 17, 2021, 9:04 PM
Jumbo wrote:Saw this article this morning and thought it was really interesting:
https://cyclingtips.com/2021/02/rough-ride-whole-body-vibrations-might-be-worse-for-you-than-you-think/

Basically, they found that seatposts make little difference, and cyclists get a level of vibration that's kind of bad for your back. And maybe tires can help.

It is also hilarious to me that they show a picture of Paris-Roubaix and then whine about weight. at P-R, weight is so irrelevant it should not even be a discussion. If you could create a 30-pound aero/dual suspension bike for that race it would be perfect but if you told someone it was 30 pounds they would scoff and not ride it.
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stu
646 posts
#6Feb 18, 2021, 12:55 AMedited
ccand51997 wrote:
There are a lot of cycling inovations that die on the vine because of the cycling cultural obsession with weight ...

The Cane Creek web site shows an 'eeSilk' seatpost which looks like a slimmed-down Thudbuster. The specs are 20 mm travel and 290 g. To me 20 mm should be enough to help on rough pavement and 290 g is close to a rigid seatpost. However it doesn't seem to be available yet and the list price is $1 per gram.

To put the weight in perspective consider Cane Creek's 50 mm travel, 580 g Thudbuster. The extra 290 g is roughly the difference between a pair of 28 mm racing tires and a pair of 38 mm GravelKings. I'm guessing all of us would prefer the GravelKings on rough stuff so why not the "heavy" Thudbuster?
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Shaun McNally
112 posts
#7Feb 18, 2021, 11:33 AM
ccand51997 wrote:
It is also hilarious to me that they show a picture of Paris-Roubaix and then whine about weight. at P-R, weight is so irrelevant it should not even be a discussion. If you could create a 30-pound aero/dual suspension bike for that race it would be perfect but if you told someone it was 30 pounds they would scoff and not ride it.

But Sky/Ineos races Roubaix with the Specialized system, and Trek-Segafredo used their Domane with both front and rear isospeed systems. So I'm not so sure why the article was so concerned with weight.
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sincos
23 posts
#8Feb 18, 2021, 7:40 PM
Shaun wrote:I thought it interesting that the things they said would work.....Thudbuster seat post, Specialized future shock, or the Trek isospeed decoupler all come at "significant weight penalty" and pretty much rendered them out of the picture in their eyes.

Actually the article said that such things might work, but they weren't tested. It is surely reasonable that they would, but then it was just as reasonable to think that the Ergon post would make some noticeable difference.
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Mudge
60 posts
#9Feb 21, 2021, 7:52 AM
Shaun wrote:

But Sky/Ineos races Roubaix with the Specialized system, and Trek-Segafredo used their Domane with both front and rear isospeed systems. So I'm not so sure why the article was so concerned with weight.

what Specialized system does Ineos use?
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DK Loves Gravel
9 posts
#10Feb 22, 2021, 12:17 AM
I received some wisdom years ago that for improved comfort on gravel one should go as wide as possible. Coming from a roadie background it took me years to heed this advice. I was overly concerned with weight and rotational mass.
This article leaves off where it should have begun; with wider tires. Comfort on gravel starts from the ground up! High volume, tubeless tires run at the lowest possible pressure on optimally wide rims.

I know I’m singing to the gravel choir here...
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stu
646 posts
#11Feb 22, 2021, 1:03 AMedited
DK wrote:This article leaves off where it should have begun; with wider tires. Comfort on gravel starts from the ground up! High volume, tubeless tires run at the lowest possible pressure on optimally wide rims.

Jan Heine explains this using unsprung mass. A tire has to manage only its own mass, hundreds of grams. A suspension has to manage the entire mass of the wheel plus some of the suspension parts, thousands of grams. Compliant stems and seatposts also have to manage a good portion of the frame and attached components, many more thousands of grams.

So for best comfort put compliance closer to the bumps and farther from the rider, i.e. in the tires.
1
Shaun McNally
112 posts
#12Feb 25, 2021, 11:55 AM
Mudge wrote:

what Specialized system does Ineos use?

https://www.bikeradar.com/news/team-sky-to-ride-full-suspension-pinarello-dogma-at-2019-paris-roubaix/
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Shaun McNally
112 posts
#13Feb 25, 2021, 11:56 AM
I'm sorry, I meant Pinarello not specialized
1
jockstick
47 posts
#14Feb 28, 2021, 11:54 PMedited
stu wrote:
Jan Heine explains this using unsprung mass. A tire has to manage only its own mass, hundreds of grams. A suspension has to manage the entire mass of the wheel plus some of the suspension parts, thousands of grams. Compliant stems and seatposts also have to manage a good portion of the frame and attached components, many more thousands of grams.

So for best comfort put compliance closer to the bumps and farther from the rider, i.e. in the tires.

While I think the conclusion is probably correct, this sounds like Jan pseudoscience to me. What exactly does “manage” mean in this case? It’s not a term I’ve ever heard used in classical mechanics.
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stu
646 posts
#15Mar 1, 2021, 2:12 AM
jockstick wrote:

While I think the conclusion is probably correct, this sounds like Jan pseudoscience to me. What exactly does “manage” mean in this case? It’s not a term I’ve ever heard used in classical mechanics.

My bad, that wasn't a direct quote.

My own thought is a bicycle is a mess of damped, coupled, driven oscillators which I couldn't begin to model accurately. But I do know whatever portion of a tire which deflects upon hitting a bump has some spring constant and some damping but very little mass compared to the rest of the bike. When a suspension works the mass of the moving parts is much greater so it needs better tuned spring rates and damping to avoid either bouncing or passing shocks through to the rider. That's what I meant by "manage".
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thumper88
198 posts
#16Mar 1, 2021, 11:00 AM
The article is worth reading in the sense it adds one more data point to your understanding of gravel riding. It offers nothing directly helpful to race performance though.
It was an evaluation based around a workplace guideline for vibration levels for safe, healthy work. I’m not going to spend the time delving into how that guideline was developed, life is short. It may be pretty good for its intended use but have little applicability to periodic exposures, like riding gravel a dozen or two times a year. Or it may be directly applicable. Or it may be semi-arbitrary even for its intended use.
But even if it is based on great science it doesn’t tell you anything about what is faster on a bike.
There is a lot of talk elsewhere about vibration to your muscles making you slower. This suggests some things that might improve that, but it's not a direct, useful study of that issue.

I don’t agree with Jan Heine on a lot of things. I like my tires to not get punctures and Ive concluded he doesn’t mind that. But yeah, tires with more volume and less air pressure are the first line of defense when take the sting out of the ride and making the bike faster on gravel. But as we all know, simply going big is not the answer. Every course is different and every tire choice is a compromise.
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