Low spoke count wheels = harsh ride?

[Clive George]

As per subject. Elsewhere somebody is saying that a stiff rim with few
spokes will give a harsher ride than a more flexible rim with lots of
spokes.

How true is this?

(I'm guessing with pneumatic tyres any effect will be lost in the noise)

cheers,
clive

 

[Tim McNamara]

In article <[email protected]>,
"Clive George" <[email protected]> wrote:

> As per subject. Elsewhere somebody is saying that a stiff rim with
> few spokes will give a harsher ride than a more flexible rim with
> lots of spokes.
>
> How true is this?

It depends- if the spoke tension is low enough for the bottom spokes to
go slack under load, that might be noticeable. But that's pretty
unlikely.

> (I'm guessing with pneumatic tyres any effect will be lost in the
> noise)

That would be my thought as well.

 

[Werehatrack]

On Fri, 24 Nov 2006 14:11:56 -0000, "Clive George"
<[email protected]> wrote:

>As per subject. Elsewhere somebody is saying that a stiff rim with few
>spokes will give a harsher ride than a more flexible rim with lots of
>spokes.
>
>How true is this?
>
>(I'm guessing with pneumatic tyres any effect will be lost in the noise)

You're guessing right. The flexibility of the rim isn't that much of
an issue, anyway; the stiffness of the completed wheel assembly is
considerably higher than the stiffness of the rim itself. IME, what's
more important is the inflation pressure (and to a lesser extent, the
size and construction) of the tire.

For purposes of comparison, consider this:

I have a Rev-X rim that was on the front of one of my bikes. When i
got the bike, it had a 700c20 tire mounted; to describe the ride as
"excessively vibratory" when that tire was inflated to max pressure
would be glossing over it somewhat. If I ran over a cigarette butt, I
could not only tell if it was plain or filtered, but whether this was
the first time it had been compressed. Reducing the pressure slightly
just resulted in pinch flats, although it did reduce the vibration
transmission a bit. I swapped out to a 700c28 tire on the front (the
rear was a 700c25 to begin with) that ran at a lower pressure, and the
vibration level was reduced quite a bit. I then swapped to a 700c32,
and got a fairly well damped ride. After months of nervously riding
that expensive wheel, I pulled it off and installed a fairly light,
old, non-aero 36-spoke wheel. Just for grins, I decided to try out
the 700c20 tire that had come with the bike. The vibration level
returned to what it had been; awful. I swapped to the 32, and it was
back to being pleasant.

I doubt that any of the low-count wheels is any stiffer than the
Rev-X.
--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Words processed in a facility that contains nuts.

 

[John Everett]

On Fri, 24 Nov 2006 09:33:08 -0600, Tim McNamara
<[email protected]> wrote:

>In article <[email protected]>,
> "Clive George" <[email protected]> wrote:
>
>> As per subject. Elsewhere somebody is saying that a stiff rim with
>> few spokes will give a harsher ride than a more flexible rim with
>> lots of spokes.
>>
>> How true is this?
>
>It depends- if the spoke tension is low enough for the bottom spokes to
>go slack under load, that might be noticeable.

But it wouldn't be noticeable for long. ;-)



jeverett3<AT>earthlink<DOT>net http://home.earthlink.net/~jeverett3

 

[Paul Cassel]

Clive George wrote:
> As per subject. Elsewhere somebody is saying that a stiff rim with few
> spokes will give a harsher ride than a more flexible rim with lots of
> spokes.
>
> How true is this?
>
Beats me, but I can say that if the WHEEL flexed enough to absorb enough
shock that you could sense the difference wheel to wheel, it'd be
unridable for that flex. My guess is that all the difference you can
sense in wheel harshness comes from tires.

To me, this is variant on the 'harsh frame material' debate. People who
seem to know their stuff have told me that if I were blindfolded, I
couldn't tell the diff between Al, Steel and C frames - all other things
being equal. I believe that.

-paul

 

[[email protected]]

Paul Cassel writes:

>> As per subject. Elsewhere somebody is saying that a stiff rim with
>> few spokes will give a harsher ride than a more flexible rim with
>> lots of spokes.

>> How true is this?

> Beats me, but I can say that if the WHEEL flexed enough to absorb
> enough shock that you could sense the difference wheel to wheel,
> it'd be unridable for that flex. My guess is that all the difference
> you can sense in wheel harshness comes from tires.

Considering that spoke elasticity accounts for about 1/100 the radial
(vertical) motion of the hub (in a 36 spoke wheel) with respect to the
road and that differences among wheels varies as the number of spokes
in the load affected zone, the person who can feel this would need to
be able to feel a bump when riding over a sheet of copier paper
(0.003").

> To me, this is variant on the 'harsh frame material' debate. People
> who seem to know their stuff have told me that if I were
> blindfolded, I couldn't tell the diff between Al, Steel and C frames
> - all other things being equal. I believe that.

The reason riders may be able to distinguish ride comfort (vertical
compliance) between one frame material and another, I believe, is from
acoustic response. On the other hand, standing in a sprint, torsional
differences are clearly evident. This can also be felt in pedaling
elasticity when seated.

Jobst Brandt

 

[Werehatrack]

On 24 Nov 2006 07:29:35 -0800, "Dirtroadie" <[email protected]>
wrote:

>Now I will stand back as others argue that there is not enough flex in
>a built up wheel to allow a noticeable difference in ride.

Perhaps more "point out" than "argue".

I liked the full disclosure inclusions, BTW. I often joke about
having a "reasonably well calibrated eyecrometer" myself.

--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Words processed in a facility that contains nuts.

 

[Johnny Sunset]

"Chas the Omnipotent!" wrote:
> ...
> You're WRONG! Completely and forever wrong! Nothing anywhere ever
> flexes, bends or moves. All solids are, well, SOLID! These are the
> learned opinions of many members of this newsgroup! ;-)

NO! NO! NO!

Modern bicycle components are "stiff, yet compliant".

--
Tom Sherman - Post Free or Die!

 

[Johnny Sunset]

Jobst Brandt wrote:
> ...
> The reason riders may be able to distinguish ride comfort (vertical
> compliance) between one frame material and another, I believe, is from
> acoustic response....

Jobst's hypothesis sounds plausible.

--
Tom "Pun Intended" Sherman - Post Free or Die!

 

[Clive George]

Thanks all for replies.

cheers,
clive

 

[Nick Payne]

We need a double-blind test. Anyone who survives riding down the road
blindfolded with different sets of wheels can be asked after each ride to
identify what sort of wheel was under them...

"Clive George" <[email protected]> wrote in message
news:[email protected]...
> As per subject. Elsewhere somebody is saying that a stiff rim with few
> spokes will give a harsher ride than a more flexible rim with lots of
> spokes.
>
> How true is this?
>
> (I'm guessing with pneumatic tyres any effect will be lost in the noise)

 

[jim beam]

[email protected] wrote:
> Paul Cassel writes:
>
>>> As per subject. Elsewhere somebody is saying that a stiff rim with
>>> few spokes will give a harsher ride than a more flexible rim with
>>> lots of spokes.
>
>>> How true is this?
>
>> Beats me, but I can say that if the WHEEL flexed enough to absorb
>> enough shock that you could sense the difference wheel to wheel,
>> it'd be unridable for that flex. My guess is that all the difference
>> you can sense in wheel harshness comes from tires.
>
> Considering that spoke elasticity accounts for about 1/100 the radial
> (vertical) motion of the hub (in a 36 spoke wheel) with respect to the
> road and that differences among wheels varies as the number of spokes
> in the load affected zone, the person who can feel this would need to
> be able to feel a bump when riding over a sheet of copier paper
> (0.003").

the usual jobstian herring that fails to acknowledge that to get that
deflection, you have to apply ~100lbs load! anyone here fail to notice
if 100lbs is applied to any part of their anatomy, however fleetingly?
no? in which case, let's focus on reality - that we're talking about
shock transmission, not static load deflection.

>
>> To me, this is variant on the 'harsh frame material' debate. People
>> who seem to know their stuff have told me that if I were
>> blindfolded, I couldn't tell the diff between Al, Steel and C frames
>> - all other things being equal. I believe that.
>
> The reason riders may be able to distinguish ride comfort (vertical
> compliance) between one frame material and another, I believe, is from
> acoustic response. On the other hand, standing in a sprint, torsional
> differences are clearly evident. This can also be felt in pedaling
> elasticity when seated.