Full size folding bicycles for camping -- Good or Bad?

On Wed, 27 May 2009 16:13:39 -0400, Dave Smith wrote:
Zane wrote:

Wheel size doesn't influence bicycle stability. One guy famously
illustrated this by building a bike with wheels the size of skate
wheels, which rode and maneuvered just like a regular one, much to
people's amazement.. (I don't have a cite for this-- this was before
the internet.) The dominant stability factor is trail on the front
wheel assembly. The notion that gyroscopic forces are involved has
been debunked long ago.

The notion that gyroscopic forces are involved has not been debunked,
just the idea that is the biggest factor. There is still some effect.
However, there are other advantages to larger wheels, like their ability
to roll over obstacles. You can mount small curbs with large wheels, but
very small wheels will stop you dead. While it make be possible to ride
a bike with skateboard sized wheels, hitting a short curb or a large
crack in the road my teach you the advantages of wearing a helmet.

especially if you try using such a toy bike on an unpaved trail.

Zane wrote:
Wheel size doesn't influence bicycle stability. One guy famously
illustrated this by building a bike with wheels the size of skate
wheels, which rode and maneuvered just like a regular one, much to
people's amazement.. (I don't have a cite for this-- this was before
the internet.) The dominant stability factor is trail on the front
wheel assembly. The notion that gyroscopic forces are involved has
been debunked long ago.

Zane

Probably, this is the study that you're referring to:

http://www.people.cornell.edu/pages/..._Mechanics.htm

On Wed, 27 May 2009 09:19:16 -0500, AZ Nomad
wrote:

Using a wal-mart folding bicycle on dirt trails is insane. Folding
bikes are already flimsy and unstable for anything but a perfect paved
roads. Combine that with it being some cheap crap from walmart and you
have a recipe for disaster. You'll be lucky if you don't end up covered
with cuts and scrapes.

Get a bike rack and take along a real bike. There are rack types other
than hitch bike racks. (just don't buy the rack from walmart if you
don't want the straps popping loose)

So, how do you really feel about Wal-Mart products? Don't hold back
now.



Elliot Richmond
Itinerant astronomy teacher

Zane wrote:

It's not a significant factor. That is, it's insignificant, which is
what I should have said instead of "involved", and is miles away from
just not being the "biggest factor".

Back to the original point, one shouldn't assume that a bike with
small wheels is any less stable than one with bigger wheels. It can
even be made _more_ stable than a typical bike by just increasing the
trail a little.


FWIW, I do quite a bit of bicycling, 15-20 miles daily, weather
permitting. I will stick to the larger wheels because I don't like going
ass over tea kettle every time I hit a bump.

On Wed, 27 May 2009 13:27:24 -0500, AZ Nomad
wrote:

On Wed, 27 May 2009 14:17:56 -0400, GaryO wrote:
On Wed, 27 May 2009 12:49:08 -0500, AZ Nomad
wrote:

On Wed, 27 May 2009 10:29:12 -0400, Steve Wolf wrote:
A folding bike does not imply a flimsy bike. There are many that have
traversed the world and were never found lacking. The only issue is
quality.

Actually it does. They invariable have very small wheels and the lack of
stability that goes with them. They are little better than pedaled skateboards.

Have you seen this one? It's no skateboard!
http://www.militarybikes.com/products.html

Amusing how they don't mention the weight. Doesn't look terrible compact
while folded either. I'd rather have a standard bike on a bike rack than
that thing taking up luggage space.

For the $800 cost, you can get a trailer hitch installed, get a receiver bike
rack, get a standard bike, and still have money left over.


They have cheaper models available too for $500. Check:
http://www.montagueco.com/

Their FAQ's claim the bike is only 1/2 pound heaver than a comparable
non-folding bike. If you notice, even manufacturers' like Trek do not
post weights until you get into the obscene price levels!

I had looked at the folding bikes several years ago when I wanted to
carry one in the truck bed, under a locking lid, and tow the trailer.
A folding bike would use less of the valuable storage space in the
bed. An external bike rack subjects the bike to weather and theft.
It is also difficult when towing a trailer, as bikes on the back of a
trailer are often lost along the road.

Instead I bought a low-to-midrange Trek bike for $600 and a rack which
I could use on the truck while towing the trailer. The folding
solution would have been cheaper, more secure, and offered better
weather protection. I just simply did not have the space with the
generator, water jugs, cooler, gas can, propane bottle, grill, patio
mat, tools, and firewood! ;-)

YMMV

...gary

On Wed, 27 May 2009 16:19:15 -0600, Zane wrote:
On Wed, 27 May 2009 16:13:39 -0400, Dave Smith
wrote:

Zane wrote:

Wheel size doesn't influence bicycle stability. One guy famously
illustrated this by building a bike with wheels the size of skate
wheels, which rode and maneuvered just like a regular one, much to
people's amazement.. (I don't have a cite for this-- this was before
the internet.) The dominant stability factor is trail on the front
wheel assembly. The notion that gyroscopic forces are involved has
been debunked long ago.

The notion that gyroscopic forces are involved has not been debunked,
just the idea that is the biggest factor. There is still some effect.

It's not a significant factor. That is, it's insignificant, which is

bull****.

You can balance on a rolling bike.

Try doing the same on a stopped bike. It is a very significant
factor and is the reason bicycles have stability. Smaller wheels
have much less. Take out a physics textbook and look up rotational
inertia if you don't believe me.

In article ,
AZ Nomad wrote:
On Wed, 27 May 2009 16:13:39 -0400, Dave Smith
wrote:
Zane wrote:

Wheel size doesn't influence bicycle stability. One guy famously
illustrated this by building a bike with wheels the size of skate
wheels, which rode and maneuvered just like a regular one, much to
people's amazement.. (I don't have a cite for this-- this was before
the internet.) The dominant stability factor is trail on the front
wheel assembly. The notion that gyroscopic forces are involved has
been debunked long ago.

The notion that gyroscopic forces are involved has not been debunked,

D*mn right it has not been debunked. It has been _proven_ to be a significant
factor in rideability. Scientists have built bicycles where there was some
not-so-simple gearing that spun a rotational mass exactly matching that of
the wheel at the same speed in the opposite direction. The 'counter-rotating'
mass was capable of being enabled/disabled, thus the _only_ difference was
in the two modes was the gyroscopic effect, or lack thereof.

As I recall, the longest distance anyone managed to traverse on one of
those bikes (Which went by the name of the "Unrideable Mark IV" *with*
the gyroscopic effect zeroed out, without falling catastrophicly off-balance
was around _3_ meters.

They also investigated other design characteristics of bicycles, including
the effect relative placement of the axle of the front wheel, relative to
the axis about which the wheel was turned for steering. If the wheel axle
trailed the axis of rotation, the bicycle was inherently unstable, and
would not steer a straight line.

This testing was reported on, more than once, in _Scientific American_.

Unfortunately this research was around 40 years ago, and is not in their
on-line archives (which only go back to 1993). One would probably need to
visit a real library, and check the hard-copy "Readers Guide to Periodical
Literature" for the late '60s, early '70s to find the stories.

On May 27, 3:19*pm, Zane wrote:
On Wed, 27 May 2009 16:13:39 -0400, Dave Smith

wrote:
Zane wrote:

Wheel size doesn't influence bicycle stability. *One guy famously
illustrated this by building a bike with wheels the size of skate
wheels, *which rode and maneuvered just like a regular one, much to
people's amazement.. *(I don't have a *cite for this-- this was before
the internet.) *The dominant stability factor is trail on the front
wheel assembly. *The notion that gyroscopic forces are involved has
been debunked long ago.

The notion that gyroscopic forces are involved has not been debunked,
just the idea that is the biggest factor. There is still some effect.

It's not a significant factor. *That is, it's insignificant, which is
what I should have said instead of "involved", and is miles away from
just not being the "biggest factor".

Back to the original point, one shouldn't assume that a bike with
small wheels is any less stable than one with bigger wheels. *It can
even be made _more_ stable than a typical bike by just increasing the
trail a little.

I remember hearing about the legendary performance of Moulten
bicycles.

http://www.moultonbicycles.co.uk

I certainly understand the dynamics. Smaller wheels mean less inertia
to overcome when accelerating or decelerating. Smaller wheels are in
fact stronger (I've had 700c rims bent or otherwise damaged).

On Wed, 27 May 2009 20:56:26 -0500,
(Robert Bonomi) wrote:

Actually you're wrong on all accounts. The article was originally
published in 1970 in "Physics Today". I recall the article vividly,
along with an analysis of the article and more experiments done by
Gordon Jennings of Cycle Magazine. I was deeply involved in
motorcycle racing and therefore was particularly interested in the
science behind bike suspension geometry so that article burned itself
into my memory.

Here is a scanned copy of the article.

http://www.phys.lsu.edu/faculty/gonz...9no9p51_56.pdf

You will notice that he failed to build an unrideable bicycle. The
counter-gyroscopic version was his first. It rode just fine. So did
the one made with furniture casters. Only the one with excessive
trail was difficult but not impossible to ride.

I used that article as the basis of a science fair project that
extended his research to include setting up a glass riding surface
covered with fine powder so that a clear track of wheel motion could
be seen from below. It became very clear that at very slow speeds
where I was working, the rider action is one of steering to put the
center of gravity back on axis with the frame. By "slow" I mean a few
inches per second. This also explains why a bike with a
locked-in-place steering head IS almost, but not quite, unrideable.

John

D*mn right it has not been debunked. It has been _proven_ to be a significant
factor in rideability. Scientists have built bicycles where there was some
not-so-simple gearing that spun a rotational mass exactly matching that of
the wheel at the same speed in the opposite direction. The 'counter-rotating'
mass was capable of being enabled/disabled, thus the _only_ difference was
in the two modes was the gyroscopic effect, or lack thereof.

As I recall, the longest distance anyone managed to traverse on one of
those bikes (Which went by the name of the "Unrideable Mark IV" *with*
the gyroscopic effect zeroed out, without falling catastrophicly off-balance
was around _3_ meters.

They also investigated other design characteristics of bicycles, including
the effect relative placement of the axle of the front wheel, relative to
the axis about which the wheel was turned for steering. If the wheel axle
trailed the axis of rotation, the bicycle was inherently unstable, and
would not steer a straight line.

This testing was reported on, more than once, in _Scientific American_.

Unfortunately this research was around 40 years ago, and is not in their
on-line archives (which only go back to 1993). One would probably need to
visit a real library, and check the hard-copy "Readers Guide to Periodical
Literature" for the late '60s, early '70s to find the stories.

On Thu, 28 May 2009 03:13:58 -0400, Neon John wrote:

On Wed, 27 May 2009 20:56:26 -0500,
(Robert Bonomi) wrote:

Actually you're wrong on all accounts. The article was originally
published in 1970 in "Physics Today". I recall the article vividly,
along with an analysis of the article and more experiments done by
Gordon Jennings of Cycle Magazine. I was deeply involved in
motorcycle racing and therefore was particularly interested in the
science behind bike suspension geometry so that article burned itself
into my memory.

Here is a scanned copy of the article.

http://www.phys.lsu.edu/faculty/gonz...9no9p51_56.pdf


Hmm, somehow I managed to leave out the following reference to more
modern work on the unrideable bicycle.

http://www.rainbowtrainers.com/default.aspx?Lev=2&ID=34

Even here they failed to make an unrideable bike. Even the rear steer
bike that the author says was unrideable isn't. I used to crank a
2-stroke bike in reverse and ride it around sitting backwards on the
seat as part of my exhibition of stunt riding.

I don't think that it's possible to make a completely unrideable bike.


John