Vibration damping

One day I was riding my bike here in Morgan Hill and encountered some of the
guys from Specialized. I asked one of them about the Zertz they had on their
bikes and he went into marketing speak telling me how great they are. I
asked if he was in engineering or marketing and he said marketing. I was and
am skeptical.

Their website
http://www.specialized.com/bc/techlab_zertz.jsp?a=b
provides a spectral chart (click "how it works" and then "see chart") which
compares axle vibration to seat post vibration.

The main problem that I see with the chart is that it compares vibration at
two locations on the bike rather than vibration with and without the Zertz.
I would like to see a comparison between vibration at the seat clamp and
handlebars (maybe even at the pedals) with and without the Zertz. I would
think that there will be less vibration, as shown in their chart, at the
seatpost compared to the axle whether or not there are Zertz.

Secondly, when I think of road buzz I think of frequencies below 50 Hz and
the chart shows little if any damping in this range. I know that higher
frequencies can cause problems but I have always associated higher
frequencies with things like the numb hands I get when using a palm sander.

This tone generator:
http://www.world-voices.com/software/nchtone.html
can give you a good "feel" for the frequencies involved.

I would guess that the higher frequencies could be more effectively
controlled with the tires than with the inserts.

My opinion is that the inserts are market hype. Does anybody have an opinion
or better yet, additional objective information?


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Relevant Pages

  • Re: Vibration damping
    ... > compares axle vibration to seat post vibration. ... > two locations on the bike rather than vibration with and ... > frequencies can cause problems but I have always associated ...
    (rec.bicycles.tech)
  • Re: Vibration damping
    ... I asked one of them about the Zertz they had on their bikes and he went into marketing speak telling me how great they are. ... compares axle vibration to seat post vibration. ... two locations on the bike rather than vibration with and without the Zertz. ...
    (rec.bicycles.tech)
  • Re: Vibration damping
    ... >> bikes and he went into marketing speak telling me how great they are. ... >> compares axle vibration to seat post vibration. ... >> two locations on the bike rather than vibration with and without the Zertz. ... >> frequencies can cause problems but I have always associated higher ...
    (rec.bicycles.tech)
  • Re: Vibration damping
    ... I asked one of them about the Zertz they had on their bikes and he went into marketing speak telling me how great they are. ... provides a spectral chart which compares axle vibration to seat post vibration. ... The main problem that I see with the chart is that it compares vibration at two locations on the bike rather than vibration with and without the Zertz. ...
    (rec.bicycles.tech)
  • Re: Vibration damping
    ... provides a spectral chart which compares axle vibration to seat post vibration. ... The main problem that I see with the chart is that it compares vibration at two locations on the bike rather than vibration with and without the Zertz. ... although I have been very happy with the two Specialized bikes I have owned and I've been very happy with their customer service. ...
    (rec.bicycles.tech)