Stem Angle/Length and Performance?

B

[email protected]

Guest
hi, just wondering what efffect stem angle and length has on handling?
i'm assuming that a shorter stem is less stable but easier to corner
with, etc and a longer stem vice-versa.

what about when it's angling above, or below level? would that make it
less stable? thanks

[email protected] wrote in news:1156003355.231944.60640
> hi, just wondering what efffect stem angle and length has on handling?
> i'm assuming that a shorter stem is less stable but easier to corner
> with, etc and a longer stem vice-versa.

Lower center of gravity = better cornering.

In article <[email protected]>,
[email protected] wrote:

> hi, just wondering what efffect stem angle and length has on handling?
> i'm assuming that a shorter stem is less stable but easier to corner
> with, etc and a longer stem vice-versa.
>
> what about when it's angling above, or below level? would that make it
> less stable? thanks

The most important components to bike handling are, in my opinion:

3) tire inflation
2) front end geometry
1) the nut attached to the handlebars

To understand the difference stem length makes to handling, try to
envision a zero-length stem, and a bizarre handlebar where each half of
the bar goes directly from that stem in a straight line to where your
hands would touch the bars (whatever kind of bars they may be).

Perhaps you can see from this example that the amount of leverage on the
steer tube that you have is a function of the length of this ridiculous
bar, and that the ridiculous bar will change its length by a very small
amount with changes in stem length, because the ridiculous bar is the
hypotenuse of a right triangle including the stem and the length of your
real handlebar from the stem attachment to your hands. a^2+b^2=c^2, as I
once told a worried nurse checking me for signs of slipping into a
coma....

Of more concern, handling-wise, is the tiller effect, which is to say
that really long stems feel odd, for reasons revolving around the paths
your hands take as you steer. I think the short version of this is that
it doesn't feel so much like you're moving one hand forward and the
other hand back, but rather that both hands are are swinging out in
front of you. To envision this better, imagine our zero-length stem
again, this time with a flat bar, and then imagine a bike with a really,
really long stem. Maybe 50 cm. Visualize how you would move your hands
to steer each bike.

I should caution that I am relatively insensitive to geometry and fit
issues until they cause me pain. I ride around on all sorts of bikes,
and as long as the seat height is right and I can reach the handlebars,
I usually make do.

Oh, as for your question about stem angle, no difference. That factor
should be solely about getting your hands at the right height for your
needs.

Probably wrong in some way,

--
Ryan Cousineau [email protected] http://www.wiredcola.com/
"I don't want kids who are thinking about going into mathematics
to think that they have to take drugs to succeed." -Paul Erdos

In article <[email protected]>,
sally <[email protected]> wrote:

> [email protected] wrote in news:1156003355.231944.60640
> > hi, just wondering what efffect stem angle and length has on handling?
> > i'm assuming that a shorter stem is less stable but easier to corner
> > with, etc and a longer stem vice-versa.

>
> Lower center of gravity = better cornering.

There are some interesting results in motorcycle racing that lead one to
a cautious application of this theory.

More importantly, on-road bicycles are pretty much purely limited by
tire traction in cornering, and if your ability to flop from one
cornering lean to another (about the roll axis) is the limiting factor
to your cornering, then holy moly that is a very tight or very fast
course. Autocross for bicycles, anyone?

Indeed, most crit-specific bikes are built with higher bottom brackets
than more typical bikes ("standard" road geometry, touring bikes)
because gaining the ability to pedal out of a corner a bit sooner is
regarded as more important than any rise in the centre of gravity.

--
Ryan Cousineau [email protected] http://www.wiredcola.com/
"I don't want kids who are thinking about going into mathematics
to think that they have to take drugs to succeed." -Paul Erdos

Did the nurse slip into a coma after you quoted the formula?

[email protected] says...

> hi, just wondering what efffect stem angle and length has on handling?
> i'm assuming that a shorter stem is less stable but easier to corner
> with, etc and a longer stem vice-versa.
>
> what about when it's angling above, or below level? would that make it
> less stable? thanks

I have noticed that shorter stems make the handling noticeably twitcher.
I didn't notice any positive effects from a short stem. When I choose
frames, I always look for one with an effective top tube length that
will require a stem of 100mm - 110mm for proper fit for me. Can't
comment on stems over 110mm because so far I haven't used any. At some
point I would expect them to make steering response too slow, the
opposite of twitchy.

Stem angle won't affect handling directly, but it will affect your
position and weight balance on the bike, and that may affect handling.
The angle, if the stem has one, will also take away from the effective
length of the stem. Mark Hickey had a chart on his web site which lets
you calculate how much effective length is lost for a given angle. You
can also calculate it with basic trigonometry by multiplying the given
stem length by the cosine of the stem angle. Cosines aren't linear, so
a stem angle of 10° shortens the stem by 1%, but a 40° angle shortens
the stem by more than 23%.

Barnard Frederick a écrit :
> [email protected] says...
>
>
>> hi, just wondering what efffect stem angle and length has on handling?
>> i'm assuming that a shorter stem is less stable but easier to corner
>> with, etc and a longer stem vice-versa.
>>
>> what about when it's angling above, or below level? would that make it
>> less stable? thanks
>>

>
> I have noticed that shorter stems make the handling noticeably twitcher.
> I didn't notice any positive effects from a short stem. When I choose
> frames, I always look for one with an effective top tube length that
> will require a stem of 100mm - 110mm for proper fit for me. Can't
> comment on stems over 110mm because so far I haven't used any. At some
> point I would expect them to make steering response too slow, the
> opposite of twitchy.
>
> Stem angle won't affect handling directly, but it will affect your
> position and weight balance on the bike, and that may affect handling.
> The angle, if the stem has one, will also take away from the effective
> length of the stem. Mark Hickey had a chart on his web site which lets
> you calculate how much effective length is lost for a given angle. You
> can also calculate it with basic trigonometry by multiplying the given
> stem length by the cosine of the stem angle. Cosines aren't linear, so
> a stem angle of 10° shortens the stem by 1%, but a 40° angle shortens
> the stem by more than 23%.
>

Just to add, not criticize :

Position is important in sprinting, too. If you do that often enough,
you want a stem that puts your body and hands in a well-balanced
position when out of the saddle sprinting. Weight distribution is
significantly different.

[email protected] wrote:
> hi, just wondering what efffect stem angle and length has on handling?
> i'm assuming that a shorter stem is less stable but easier to corner
> with, etc and a longer stem vice-versa.
>
> what about when it's angling above, or below level? would that make it
> less stable? thanks

I think stem angle and length has a much larger effect on comfort than
bicycle ride performance, cornering. Genrally, a well fitted bicycle
WILL corner and perform the best.

Barnard Frederick writes:

>> hi, just wondering what effect stem angle and length has on
>> handling? I'm assuming that a shorter stem is less stable but
>> easier to corner with, etc and a longer stem vice-versa.

>> what about when it's angling above, or below level? would that
>> make it less stable? thanks

> I have noticed that shorter stems make the handling noticeably
> twitcher. I didn't notice any positive effects from a short stem.
> When I choose frames, I always look for one with an effective top
> tube length that will require a stem of 100mm - 110mm for proper fit
> for me. Can't comment on stems over 110mm because so far I haven't
> used any. At some point I would expect them to make steering
> response too slow, the opposite of twitchy.

I think you'll find that any change in stem length will affect your
appreciation of how the bicycle handles but does not affect how well
it can be controlled. Stem length is a way of using a shorter frame
for riders with a longer torso (taller riders). It saves frame weight
while giving the rider a proper fit. With frames no longer being made
in many sizes to fit specific riders, stem and seat post length are
used to achieve this. Smaller riders using shorter stems make this
apparent. They are not hindered in maneuvering by shorter stems and
handle bicycles as well as taller riders with longer stems.

> Stem angle won't affect handling directly, but it will affect your
> position and weight balance on the bike, and that may affect
> handling. The angle, if the stem has one, will also take away from
> the effective length of the stem. Mark Hickey had a chart on his
> web site which lets you calculate how much effective length is lost
> for a given angle. You can also calculate it with basic
> trigonometry by multiplying the given stem length by the cosine of
> the stem angle. Cosines aren't linear, so a stem angle of 10?
> shortens the stem by 1%, but a 40 degree angle shortens the stem by
> more than 23%.

(cosine effect, cos(40)=0.766)

Handlebar width also has no effect on handling in the range of widths
offered but is selected to allow the rider a straighter line from
shoulder to hands to achieve good breathing, a straighter arm
requiring less effort.

Jobst Brandt

On Sun, 20 Aug 2006 07:08:57 -0400, Barnard Frederick
<[email protected]> wrote:

>[email protected] says...
>
>> hi, just wondering what efffect stem angle and length has on handling?
>> i'm assuming that a shorter stem is less stable but easier to corner
>> with, etc and a longer stem vice-versa.
>>
>> what about when it's angling above, or below level? would that make it
>> less stable? thanks

>
>I have noticed that shorter stems make the handling noticeably twitcher.
>I didn't notice any positive effects from a short stem. When I choose
>frames, I always look for one with an effective top tube length that
>will require a stem of 100mm - 110mm for proper fit for me. Can't
>comment on stems over 110mm because so far I haven't used any. At some
>point I would expect them to make steering response too slow, the
>opposite of twitchy.
>
>Stem angle won't affect handling directly, but it will affect your
>position and weight balance on the bike, and that may affect handling.
>The angle, if the stem has one, will also take away from the effective
>length of the stem. Mark Hickey had a chart on his web site which lets
>you calculate how much effective length is lost for a given angle. You
>can also calculate it with basic trigonometry by multiplying the given
>stem length by the cosine of the stem angle. Cosines aren't linear, so
>a stem angle of 10° shortens the stem by 1%, but a 40° angle shortens
>the stem by more than 23%.

Dear Barnard,

Mark Hickey's chart is still there:

http://www.habcycles.com/fitting.html

Cheers,

Carl Fogel

On Sun, 20 Aug 2006 10:52:56 -0600, [email protected] wrote:

>
>Mark Hickey's chart is still there:
>
>http://www.habcycles.com/fitting.html

Looks like his chart is upside down. Stems drop, they don't rise! What
could he be thinking ?

On another topic, has anyone (here or some other place in the world)
experimented with very long wheelbase bikes where the stem is
installed in the reverse direction to get a proper fit ? It seems like
you could create a wheelbase quite a bit longer. Might be an
interesting choice for a touring bike.

On Sun, 20 Aug 2006 21:57:28 GMT, - Bob - <[email protected]>
wrote:

>On Sun, 20 Aug 2006 10:52:56 -0600, [email protected] wrote:
>
>>
>>Mark Hickey's chart is still there:
>>
>>http://www.habcycles.com/fitting.html

>
>Looks like his chart is upside down. Stems drop, they don't rise! What
>could he be thinking ?
>
>On another topic, has anyone (here or some other place in the world)
>experimented with very long wheelbase bikes where the stem is
>installed in the reverse direction to get a proper fit ? It seems like
>you could create a wheelbase quite a bit longer. Might be an
>interesting choice for a touring bike.

Dear Bob,

Maintaining a laudablly neutral attitude, I'll simply point out that
you can flip Mark's chart upside-down to suit your tastes.

Cheers,

Carl Fogel

Ryan Cousineau wrote:
> In article <[email protected]>,
> sally <[email protected]> wrote:
>
> > [email protected] wrote in news:1156003355.231944.60640
> > > hi, just wondering what efffect stem angle and length has on handling?
> > > i'm assuming that a shorter stem is less stable but easier to corner
> > > with, etc and a longer stem vice-versa.

> >
> > Lower center of gravity = better cornering.

>
> There are some interesting results in motorcycle racing that lead one to
> a cautious application of this theory.

While the benefits of a lower center of gravity (CG) are obvious for
multi-track vehicles, there does not appear to be any reason why CG
should affect available cornering traction on a single-track vehicle.

> More importantly, on-road bicycles are pretty much purely limited by
> tire traction in cornering, and if your ability to flop from one
> cornering lean to another (about the roll axis) is the limiting factor
> to your cornering, then holy moly that is a very tight or very fast
> course. Autocross for bicycles, anyone?...

While a bicycle with a low combined rider/bicycle CG is more fun to
ride due to the faster "roll rate" and lower control inputs [1], it
does not appear to confer other advantages.

[1] Based on riding a bicycle with a combined rider/bicycle CG of
approximately 0.45-m.
--
Tom Sherman - Behind the Cheddar Curtain

Ryan Cousineau wrote:
> ...
> Of more concern, handling-wise, is the tiller effect, which is to say
> that really long stems feel odd, for reasons revolving around the paths
> your hands take as you steer. I think the short version of this is that
> it doesn't feel so much like you're moving one hand forward and the
> other hand back, but rather that both hands are are swinging out in
> front of you. To envision this better, imagine our zero-length stem
> again, this time with a flat bar, and then imagine a bike with a really,
> really long stem. Maybe 50 cm. Visualize how you would move your hands
> to steer each bike....

The bike I ride the most has approximately 0.45-m of tiller. While the
tiller effect is rather noticeable at low speeds, I quickly become
accustomed to it, and bicycles with conventional steering end up
seeming rather odd in their handling. At higher speeds (80+ kph) the
tiller makes the bike very directionally stable.
--
Tom Sherman - Behind the Cheddar Curtain

- Bob - <[email protected]> wrote:

>On Sun, 20 Aug 2006 10:52:56 -0600, [email protected] wrote:
>
>>Mark Hickey's chart is still there:
>>
>>http://www.habcycles.com/fitting.html

>
>Looks like his chart is upside down. Stems drop, they don't rise! What
>could he be thinking ?

Heh. The chart is relative to the horizon, not the steer tube. If
you have a stem that literally drops relative to "flat", you have an
unusual stem (especially these days when virtually all stems seem to
have some rise).

>On another topic, has anyone (here or some other place in the world)
>experimented with very long wheelbase bikes where the stem is
>installed in the reverse direction to get a proper fit ? It seems like
>you could create a wheelbase quite a bit longer. Might be an
>interesting choice for a touring bike.

You go first - let the rest of us know how it works. ;-)

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the \$795 ti frame

- Bob - wrote:
> ...
> On another topic, has anyone (here or some other place in the world)
> experimented with very long wheelbase bikes where the stem is
> installed in the reverse direction to get a proper fit ? It seems like
> you could create a wheelbase quite a bit longer. Might be an
> interesting choice for a touring bike.

Like this: <http://www.ransbikes.com/images06/StratXP/8STXPside.jpg>?

--
Tom Sherman - Behind the Cheddar Curtain

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