On bicycle vibrations.

Attention! Attention!

Actual "tech" in the following link.

http://www.researchgate.net/publication/270917366_Using_Power_as_a_Metric_to_Quantify_Vibr ation_Transmitted_to_the_Cyclist

Note that the frequency band where most energy is transmitted to the
cyclists hands extends from around 30Hz to 50Hz.

The frequency distribution at the seat post may be slightly different
due to the differences in stiffness of the vibration transmission path,
but I doubt there will be "notes" well up in the audible spectrum.

Your arse is much better at absorbing vibration energy than each of your
hands, but both hands absorb about as much as your arse.

About 8W total is absorbed by your arse and hands.

Also, though the differences between the two bikes was not significant,
bike A was reputed to be less comfortable, and indeed the results showed
the same - although by a small measured difference.

--
JS

On Sunday, December 6, 2015 at 11:37:11 PM UTC, James wrote:
Attention! Attention!

Actual "tech" in the following link.

What are you, some kind of a troll? Don't you know this is the anti-everything forum? Actual tech content is like telling a woman to mind her dishwashing and her laundry.
http://www.researchgate.net/publication/270917366_Using_Power_as_a_Metric_to_Quantify_Vibr ation_Transmitted_to_the_Cyclist

Note that the frequency band where most energy is transmitted to the
cyclists hands extends from around 30Hz to 50Hz.

Doesn't surprise me at all. Anybody who's built his own loudspeakers knows where the power is. Also, suspension specialialists in automobiles and especially in truck tyres are not keen on those frequencies at all. What surprises me more is that it has taken so long for the good word to reach bicycling.

The frequency distribution at the seat post may be slightly different
due to the differences in stiffness of the vibration transmission path,
but I doubt there will be "notes" well up in the audible spectrum.

The power in higher frequencies is low. But repetitive stress injuries to the hand aren't necessarily done by power; instead it is duration that matters.

Your arse is much better at absorbing vibration energy than each of your
hands, but both hands absorb about as much as your arse.

I'm extremely sensitive to vibrations in my hands. I mean attudinally, because I earn my living with them, a writer being a sort of manual worker who operates a keyboard whenever he is isn't sitting looking at the eucaluptus outside his window. But bike grips and saddles on my sort of bike need to be very incompetently designed not to be able to deal with with the grosser vibrations that have real power; it's the microvibrations that get through that over time do the harm.

About 8W total is absorbed by your arse and hands.

Also, though the differences between the two bikes was not significant,
bike A was reputed to be less comfortable, and indeed the results showed
the same - although by a small measured difference.

I had a really beautifully built bike from Peugeot, fillet brazed by an artist, but the tubes were misspecified so that every road irregularity ended up in my hands and bum, so that I buzzed after even the shortest ride. I think these researchers get it right. 8W -- and that incompetently designed bike surely was worse than that -- over time is like a low voltage wire on your tongue but at a high enough amperage to give you a nasty burn.

Andre Jute
Steel is real

PS: I'm reposting the link on the Thorn forum, where there several fellows interested in this sort of thing. Thanks for sharing.

This was a great read. Thanks for posting.

dkl

On Mon, 7 Dec 2015 09:37:02 +1000, James
wrote:

Attention! Attention!

If you're expecting a military salute, forget it.

http://www.researchgate.net/publication/270917366_Using_Power_as_a_Metric_to_Quantify_Vibr ation_Transmitted_to_the_Cyclist

Nice read. Thanks. It would have been more interesting if they had
tested different frame geometries and construction methods, such as
aluminum vs steel, spring and shock absorber suspension, and fat vs
thin tires.

Note that the frequency band where most energy is transmitted to the
cyclists hands extends from around 30Hz to 50Hz.

If it were done in Europe, I might suspect 50 Hz power line
interference. However, it was done in Canada, which is 60 Hz, so
that's not a cause. 30-50 Hz is a rather high frequency for vibration
and seems too low for a mechanical resonance (tap on a suspended steel
frame with a small hammer and listen for the tone pitch). 50 Hz would
require a 3000 rpm rotation of the wheel. The report is probably ok,
but I'm still rather suspicious.

About 8W total is absorbed by your arse and hands.

That explains why I feel warmer when I ride my bicycle.

I'm surprised that they didn't just attach an Android tablet to the
seat post, fire up a vibration analyzer app, and go for a (simulated)
ride:
https://play.google.com/store/search?q=vibration%20analyzer&c=apps&hl=en
Looks like a few apps worth trying.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

On 08/12/15 05:21, Jeff Liebermann wrote:
On Mon, 7 Dec 2015 09:37:02 +1000, James
wrote:

Attention! Attention!

If you're expecting a military salute, forget it.

http://www.researchgate.net/publication/270917366_Using_Power_as_a_Metric_to_Quantify_Vibr ation_Transmitted_to_the_Cyclist

Nice read. Thanks. It would have been more interesting if they had
tested different frame geometries and construction methods, such as
aluminum vs steel, spring and shock absorber suspension, and fat vs
thin tires.

Note that the frequency band where most energy is transmitted to the
cyclists hands extends from around 30Hz to 50Hz.

If it were done in Europe, I might suspect 50 Hz power line
interference. However, it was done in Canada, which is 60 Hz, so
that's not a cause. 30-50 Hz is a rather high frequency for vibration
and seems too low for a mechanical resonance (tap on a suspended steel
frame with a small hammer and listen for the tone pitch). 50 Hz would
require a 3000 rpm rotation of the wheel. The report is probably ok,
but I'm still rather suspicious.

It has nothing to do with tapping the frame and listening for it to
ring. It is not even about plucking a spoke and listening for a note.


About 8W total is absorbed by your arse and hands.

That explains why I feel warmer when I ride my bicycle.

I'm surprised that they didn't just attach an Android tablet to the
seat post, fire up a vibration analyzer app, and go for a (simulated)
ride:
https://play.google.com/store/search?q=vibration%20analyzer&c=apps&hl=en
Looks like a few apps worth trying.




Yes, there may be other possibilities these days. Perhaps they sought
more accuracy.

--
JS

On Monday, December 7, 2015 at 7:21:30 PM UTC, Jeff Liebermann wrote:
On Mon, 7 Dec 2015 09:37:02 +1000, James
wrote:

Attention! Attention!

If you're expecting a military salute, forget it.

http://www.researchgate.net/publication/270917366_Using_Power_as_a_Metric_to_Quantify_Vibr ation_Transmitted_to_the_Cyclist

Nice read. Thanks. It would have been more interesting if they had
tested different frame geometries and construction methods, such as
aluminum vs steel, spring and shock absorber suspension, and fat vs
thin tires.

I blame global warming for your lack of satisfaction, Jeff. If those other ******s didn't get all the grants for inventing non-existent global warming, there would be much more money for significant research like whether steel is real.

Andre Jute
Relevance and context, my old son -- Tom Sheridan, a fave teacher