RST #541: Why does the stem stick out forward?

Really Stupid Question No. 541:
Why does the stem stick out forward?

Why does no one buy a bike with a longer than necessary top tube --
say to get more toe room between the pedal and the front mudguard --
and then bring the handlebars back within reach by turning the stem
around to point towards the rider rather than forward?

Such a scheme would give a longer wheelbase and thus a smoother ride.

Andre Jute
Coming up with a dilly

On Dec 3, 8:44*am, Andre Jute wrote:
Really Stupid Question No. 541:
Why does the stem stick out forward?

Why does no one buy a bike with a longer than necessary top tube --
say to get more toe room between the pedal and the front mudguard --
and then bring the handlebars back within reach by turning the stem
around to point towards the rider rather than forward?

Such a scheme would give a longer wheelbase and thus a smoother ride.

Bicycles already have the weight biased toward the rear wheel and this
would increase that bias. If a longer wheelbase is desired then I'd
think a better approach would be to increase the length of the rear
stays which would improve load carrying options and have a better
chainline in addition to more even loading of the two wheels.

Use of a negative stem extension would also change the steering feel.
A push to the right on the handlebars would swing the bars to the
left, similar to the tiller-steering on some boats.

On 12/3/2008 8:00 AM peter wrote:

On Dec 3, 8:44 am, Andre Jute wrote:
Really Stupid Question No. 541:
Why does the stem stick out forward?

Why does no one buy a bike with a longer than necessary top tube --
say to get more toe room between the pedal and the front mudguard --
and then bring the handlebars back within reach by turning the stem
around to point towards the rider rather than forward?

Such a scheme would give a longer wheelbase and thus a smoother ride.

Bicycles already have the weight biased toward the rear wheel and this
would increase that bias. If a longer wheelbase is desired then I'd
think a better approach would be to increase the length of the rear
stays which would improve load carrying options and have a better
chainline in addition to more even loading of the two wheels.

Use of a negative stem extension would also change the steering feel.
A push to the right on the handlebars would swing the bars to the
left, similar to the tiller-steering on some boats.

Really? That is /so/ non-intuitive to me. Which is not meant as disputing
what you're saying, but a statement that my brain just doesn't get it.

--
Mike "Rocket J Squirrel"
Bend, Oregon

On Dec 3, 10:39*am, Mike Rocket J Squirrel
wrote:
On 12/3/2008 8:00 AM peter wrote:





On Dec 3, 8:44 am, Andre Jute wrote:
Really Stupid Question No. 541:
Why does the stem stick out forward?

Why does no one buy a bike with a longer than necessary top tube --
say to get more toe room between the pedal and the front mudguard --
and then bring the handlebars back within reach by turning the stem
around to point towards the rider rather than forward?

Such a scheme would give a longer wheelbase and thus a smoother ride.

Bicycles already have the weight biased toward the rear wheel and this
would increase that bias. *If a longer wheelbase is desired then I'd
think a better approach would be to increase the length of the rear
stays which would improve load carrying options and have a better
chainline in addition to more even loading of the two wheels.

Use of a negative stem extension would also change the steering feel.
A push to the right on the handlebars would swing the bars to the
left, similar to the tiller-steering on some boats.

Really? That is /so/ non-intuitive to me. Which is not meant as disputing
what you're saying, but a statement that my brain just doesn't get it.

What exactly don't you get? Just think about a stem and bars pointing
towards the saddle instead of the front wheel. To turn the front
wheel right, you push the bars to the left. Or just take a bike you
already have and turn the bars so they point towards the saddle. If
your cables have enough slack you can get them most of the way
around. Then move the bars and watch which way the wheel goes.





--
Mike "Rocket J Squirrel"
Bend, Oregon- Hide quoted text -

- Show quoted text -

On Dec 3, 4:53*pm, "
wrote:
On Dec 3, 10:39*am, Mike Rocket J Squirrel



wrote:
On 12/3/2008 8:00 AM peter wrote:

On Dec 3, 8:44 am, Andre Jute wrote:
Really Stupid Question No. 541:
Why does the stem stick out forward?

Why does no one buy a bike with a longer than necessary top tube --
say to get more toe room between the pedal and the front mudguard --
and then bring the handlebars back within reach by turning the stem
around to point towards the rider rather than forward?

Such a scheme would give a longer wheelbase and thus a smoother ride..

Bicycles already have the weight biased toward the rear wheel and this
would increase that bias. *If a longer wheelbase is desired then I'd
think a better approach would be to increase the length of the rear
stays which would improve load carrying options and have a better
chainline in addition to more even loading of the two wheels.

Use of a negative stem extension would also change the steering feel.
A push to the right on the handlebars would swing the bars to the
left, similar to the tiller-steering on some boats.

Really? That is /so/ non-intuitive to me. Which is not meant as disputing
what you're saying, but a statement that my brain just doesn't get it.

What exactly don't you get? *Just think about a stem and bars pointing
towards the saddle instead of the front wheel. *To turn the front
wheel right, you push the bars to the left. *Or just take a bike you
already have and turn the bars so they point towards the saddle. *If
your cables have enough slack you can get them most of the way
around. *Then move the bars and watch which way the wheel goes.



--
Mike "Rocket J Squirrel"
Bend, Oregon- Hide quoted text -

- Show quoted text -

You're turning a crumb of misunderstanding into a sermon-on-the-mount
meal for thousands, Russell. Instead I urge you to think about what
happens to the steering when you do the job properly: take the
handlebar out of the stem, loosen the stembolts, turn the stem 180
degrees, refit the handlebar. Now the front wheel turns right when you
turn the handlebars clockwise, as it did before, but the displacement
of the junction of stem and handlebar instead of being to the right is
to the left of the rider; however, it is still in a clockwise
direction.

Andre Jute
Visit Jute on Amps at http://members.lycos.co.uk/fiultra/
"wonderfully well written and reasoned information
for the tube audio constructor"
John Broskie TubeCAD & GlassWare
"an unbelievably comprehensive web site
containing vital gems of wisdom"
Stuart Perry Hi-Fi News & Record Review

wrote:
What exactly don't you get? Just think about a stem and bars pointing
towards the saddle instead of the front wheel. To turn the front
wheel right, you push the bars to the left. Or just take a bike you
already have and turn the bars so they point towards the saddle. If
your cables have enough slack you can get them most of the way
around. Then move the bars and watch which way the wheel goes.

Perhaps I ride differently than you, but I never push the bars to the
left or the right. At speed, I lean the bike to turn. When maneuvering
slowly, I push the bars forward and backward, not side to side. In
either of these scenarios, it doesn't matter whether the bars are
forward of or behind the steering axis, the effect is the same.

On Dec 3, 4:00 pm, peter wrote:
On Dec 3, 8:44 am, Andre Jute wrote:

Really Stupid Question No. 541:
Why does the stem stick out forward?

Why does no one buy a bike with a longer than necessary top tube --
say to get more toe room between the pedal and the front mudguard --
and then bring the handlebars back within reach by turning the stem
around to point towards the rider rather than forward?

Such a scheme would give a longer wheelbase and thus a smoother ride.

Bicycles already have the weight biased toward the rear wheel and this
would increase that bias.

Good point.

If a longer wheelbase is desired then I'd
think a better approach would be to increase the length of the rear
stays which would improve load carrying options and have a better
chainline in addition to more even loading of the two wheels.

No one said that a longer wheelbase was desired. In my example a
longer wheelbase was a byproduct of wanting more toe room.

Use of a negative stem extension would also change the steering feel.

I don't see why.

A push to the right on the handlebars would swing the bars to the
left, similar to the tiller-steering on some boats.

Nonsense; a tiller is turned in the opposite direction to which you
want to steer the boat (better for the easily confused to look at the
rudder), a bicycle handlebar *wherever it is attached to the stem* is
turned in the desired direction of travel.

Whatever you're on, don't go on the water while you on it.

Andre Jute
Sometime a dinghy and trans-Atlantic racer

On Dec 3, 5:09*pm, Brian Nystrom wrote:
wrote:
What exactly don't you get? *Just think about a stem and bars pointing
towards the saddle instead of the front wheel. *To turn the front
wheel right, you push the bars to the left. *Or just take a bike you
already have and turn the bars so they point towards the saddle. *If
your cables have enough slack you can get them most of the way
around. *Then move the bars and watch which way the wheel goes.

Perhaps I ride differently than you, but I never push the bars to the
left or the right. At speed, I lean the bike to turn. When maneuvering
slowly, I push the bars forward and backward, not side to side. In
either of these scenarios, it doesn't matter whether the bars are
forward of or behind the steering axis, the effect is the same.

Then, except for the fashion for very short wheelbases, why does no
one have the stem pointing backwards?

What is the point of the stem anyway (except to get racers right down
on too-short bikes)?

Point of interest: the modern Copenhagen reincarnation of the immortal
Pedersen bike has zero stem length; the moustache bars are attached
directly on the top of the quill and fastened with the quill's
expander bolt.

Andre Jute
http://members.lycos.co.uk/fiultra/B...%20Smover.html

On Dec 3, 9:09 am, Brian Nystrom wrote:

Perhaps I ride differently than you, but I never push the bars to the
left or the right. At speed, I lean the bike to turn. When maneuvering
slowly, I push the bars forward and backward, not side to side. In
either of these scenarios, it doesn't matter whether the bars are
forward of or behind the steering axis, the effect is the same.


Actually you are turning the bars-it's called countersteering and it's
how all single track vehicles change direction above a walking pace.
You turn the bars left to turn right and vise versa. However the
movements on a bicycle are very small and hard to demonstrate but much
easier on a motorcycle-bigger forces and heavier front wheels. You can
demonstrate it on a bike but I advise you to do it in an empty parking
lot. My memory is that the famous picture of Jobst at an extreme lean
angle will show that his wheel is turned opposite to the direction
that bike is going. It's also easy to see in motorcycle pictures.
Countersteering is a hot topic in motorcycling where many still think
you steer by leaning but I once saw an SAE paper demonstrating it by
use of conical sections. Very esoteric.
Phil Brown

On Dec 3, 11:18*am, Andre Jute wrote:
On Dec 3, 4:00 pm, peter wrote:

On Dec 3, 8:44 am, Andre Jute wrote:

Really Stupid Question No. 541:
Why does the stem stick out forward?

Why does no one buy a bike with a longer than necessary top tube --
say to get more toe room between the pedal and the front mudguard --
and then bring the handlebars back within reach by turning the stem
around to point towards the rider rather than forward?

Such a scheme would give a longer wheelbase and thus a smoother ride.

Bicycles already have the weight biased toward the rear wheel and this
would increase that bias.

Good point.

If a longer wheelbase is desired then I'd
think a better approach would be to increase the length of the rear
stays which would improve load carrying options and have a better
chainline in addition to more even loading of the two wheels.

No one said that a longer wheelbase was desired. In my example a
longer wheelbase was a byproduct of wanting more toe room.

My fendered bike already has sufficient room between my shoe and
mudguard - additional space would serve no purpose. If yours has some
overlap there are a variety of ways the frame geometry could be
redesigned to correct that without reversing the stem. My bikes that
do have overlap between my shoe and front tire appear to be
deliberately designed for as short a wheelbase as feasible for the
700c wheelsize.

Use of a negative stem extension would also change the steering feel.

I don't see why.

A push to the right on the handlebars would swing the bars to the
left, similar to the tiller-steering on some boats.

Nonsense; a tiller is turned in the opposite direction to which you
want to steer the boat (better for the easily confused to look at the
rudder), a bicycle handlebar *wherever it is attached to the stem* is
turned in the desired direction of travel.

Whatever you're on, don't go on the water while you on it.

When I sit on my bike and give a push on the end of the handlebars
directly toward the left, the handlebars swing so the right end moves
left and forward and the bike steers to the left. If I flipped the
stem over (i.e. facing back) and again gave a push on the bars
directly to the left, the bars would now swing so the right end would
move left and backward and the bike would steer to the right.

Similarly in my sailboat when I push directly to the left on the end
of the tiller, the tiller end swings left and back, and the boat turns
to starboard.

BTW, I don't think this change would make the bike hard to ride - just
that it would feel different.