Why are stems 9-11cm long?
pm
stem was a holdover from days when top tubes were fitted very high;
the acute angle in the stem allowed racers to get their bars down and
forward to get a good aero position. On most bikes today the top tubes
are built lower and the bars are clamped above the top tube, so that
constraint no longer applies.
In searching the internet, I see many people claim that shorter stems
will adversely impact bike handling, making it faster or twitchier,
causing problems for rough roads and descents. This doesn't make sense
to me. If there is an effect on handling, it ought to boil down to
where the hands are placed relative to the steering axis. A long stem
and drop bars put the hands way in front of the steering axis. If this
is good for rough roads and descents, then downhiller MTBs, which use
shorter stems and bars with lots of rise and pullback, would be quite
unsuited to their purpose. Meanwhile, motorcycles, seeing as they
outweigh their riders and travel at even higher speeds, are in need of
still more stable handling-- and most of these place the rider's hands
significantly *behind* the steering axis.
One could imagine leaving the rider's points of contact the same,
stretching out the top tube and using a shorter stem. What positive or
negative effects would this have? You'd have a longer wheelbase,
(which would slow rather than quicken the handling?) You'd eliminate
toe overlap. You'd improve the amount of braking force you can apply
before lifting the rear wheel. On the other hand, the frame might be
less stiff, and weight distribution might be more biased toward the
rear wheel.
(Note, I'm not talking about the effects of shortening the stem on the
same frame; rather, I'm asking about the effects of moving the
steering axis forward with the rider position unchanging; i.e.
lengthening the top tube by the same amount as you shorten the stem.)
I could imagine it having an effect on stability when you stand up and
honk -- but If anything, my bike with drop bars, putting the hands
further in front of the steering axis, is far less stable out of the
saddle than my flatbar bike.
So why are stems so long?
-pm
A Muzi
Adjust as you wish to your own set of criteria, there are lots of
products now. Long, short, track, tall, whatever. Plus adapters.
Note for 'big guys': If you add hi-rise bars and a short stem you dance
with rear wheel trouble, shifting weight to the back of the bike and
reducing the amount of road shock absorbed by the rider.
--
Andrew Muzi
<www.yellowjersey.org/>
Open every day since 1 April, 1971
** Posted from http://www.teranews.com **
Steve Gravrock
> One could imagine leaving the rider's points of contact the same,
> stretching out the top tube and using a shorter stem. What positive or
> negative effects would this have? You'd have a longer wheelbase,
> (which would slow rather than quicken the handling?) You'd eliminate
> toe overlap. You'd improve the amount of braking force you can apply
> before lifting the rear wheel. On the other hand, the frame might be
> less stiff, and weight distribution might be more biased toward the
> rear wheel.
>
> (Note, I'm not talking about the effects of shortening the stem on the
> same frame; rather, I'm asking about the effects of moving the
> steering axis forward with the rider position unchanging; i.e.
> lengthening the top tube by the same amount as you shorten the stem.)
>
> I could imagine it having an effect on stability when you stand up and
> honk -- but If anything, my bike with drop bars, putting the hands
> further in front of the steering axis, is far less stable out of the
> saddle than my flatbar bike.
The most obvious difference will probably be a greater tendency to
wheelie when climbing steep hills seated.
> So why are stems so long?
I'd guess traditional aesthetics and fit. Designing for a stem in the
9-11cm range means that the bike can fit riders who need a bit more or
less reach than average. A bike that's designed for a very short stem
can't accomodate anyone who needs less reach. That's not a big problem
on montain bikes, which seem less sensitive to reach in general, but on
road bikes I think it would push a lot of people onto smaller frames
than they would otherwise ride.
Mike Jacoubowsky
| will adversely impact bike handling, making it faster or twitchier,
| causing problems for rough roads and descents. This doesn't make sense
| to me. If there is an effect on handling, it ought to boil down to
| where the hands are placed relative to the steering axis. A long stem
| and drop bars put the hands way in front of the steering axis. If this
| is good for rough roads and descents, then downhiller MTBs, which use
| shorter stems and bars with lots of rise and pullback, would be quite
| unsuited to their purpose. Meanwhile, motorcycles, seeing as they
| outweigh their riders and travel at even higher speeds, are in need of
| still more stable handling-- and most of these place the rider's hands
| significantly *behind* the steering axis.
Bikes aren't made to work without a rider, and the interaction between bike and rider is dynamic (the rider learns how to make the bike do what is required). When I raced, my road bike, a Cinelli, had a pretty long top tube and required a very short stem (I actually used as short as 7.5cm at one point) while my criterium bike, a Bob Jackson, had a very short top tube and required an 11cm stem. I could descend and climb very well on each (the Bob Jackson had an advantage in Criteriums due to a higher bottom bracket and slightly steeper head angle, although truthfully, the Cinelli was the more-capable all-around bike when it came to a feeling of sure-footedness).
The point is that, within reasonable limits, you adapt and adjust, pretty easily, to differences in handling caused by different length stems and such.
--Mike-- Chain Reaction Bicycles
www.ChainReactionBicycles.com
"pm" <zzyzx...@gmail.com> wrote in message news:bdbaa3f1-2d83-4af7...@l8g2000prm.googlegroups.com...
invasiv...@gmail.com
> So why are stems so long?
>
> -pm
They aren't. A typical bicycle is generally wanted to have a wheel-
base of about a metre, maybe a scosh more. For some of us, that
would require one of:
a) not actually a metre(orso) wheelbase
b) a weird front end geometry to compensate for a long top-tube
c) a seventeen inch rear wheel
d) a seat-post setback of around zero-point-one metres
e) a really fabulous hunch
f) a "9-11 cm stem"*
For some people, a short top-tube and a 63deg headtube (27deg
rake) and a four cm stem are fine. Just not as aesthetically
pleasing.
* actually a 14cm stem with long-reach bullhorns
PS: motorcycles:
1) 44-46deg fronts
2) steering bumpers
2.5[a. revised]) significant gyroscopic effects
3) generally >250kg and up
Kinky Cowboy
wrote:
>In searching the internet, I see many people claim that shorter stems
>will adversely impact bike handling, making it faster or twitchier,
>causing problems for rough roads and descents. This doesn't make sense
>to me. If there is an effect on handling, it ought to boil down to
>where the hands are placed relative to the steering axis. A long stem
>and drop bars put the hands way in front of the steering axis. If this
>is good for rough roads and descents, then downhiller MTBs, which use
>shorter stems and bars with lots of rise and pullback, would be quite
>unsuited to their purpose.
But they also use much wider bars than road bikes; it's not simply how
far fore or aft of the steering axis you put you hands, it's the
radial distance from the contact point to the axis which affects
"twitchiness", where small hand movements cause large changes of
steering angle. The corollary is large radial distance gives more
leverage to resist/correct bump-steer
You can see this easily on a road bike, where steering is twitchy
holding the tops right next to the stem but much less so when holding
the hoods, but you can do the same experiment on a flat bar XC bike by
moving your hands inside the levers, and in this case there is no
fore/aft movement of the contact point to confuse the issue.
Kinky Cowboy*
*Batteries not included
May contain traces of nuts
Your milage may vary
jim beam
> On Sun, 20 Jul 2008 14:48:08 -0700 (PDT), pm <zzyzx...@gmail.com>
> wrote:
>
>> In searching the internet, I see many people claim that shorter stems
>> will adversely impact bike handling, making it faster or twitchier,
>> causing problems for rough roads and descents. This doesn't make sense
>> to me. If there is an effect on handling, it ought to boil down to
>> where the hands are placed relative to the steering axis. A long stem
>> and drop bars put the hands way in front of the steering axis. If this
>> is good for rough roads and descents, then downhiller MTBs, which use
>> shorter stems and bars with lots of rise and pullback, would be quite
>> unsuited to their purpose.
>
> But they also use much wider bars than road bikes; it's not simply how
> far fore or aft of the steering axis you put you hands, it's the
> radial distance from the contact point to the axis which affects
> "twitchiness", where small hand movements cause large changes of
> steering angle. The corollary is large radial distance gives more
> leverage to resist/correct bump-steer
bump steer??? is the wheel axis laterally offset from the steering axis
like a car???
>
> You can see this easily on a road bike, where steering is twitchy
> holding the tops right next to the stem but much less so when holding
> the hoods, but you can do the same experiment on a flat bar XC bike by
> moving your hands inside the levers, and in this case there is no
> fore/aft movement of the contact point to confuse the issue.
no, what you're observing is the effect of your arm influencing the
handlebar position as it moves relative to your body. it's not "bump
steer" as such. that's why there's no effect if you remove your hands
from the bar completely.
Anthony DeLorenzo
> So why are stems so long?
Regarding bikes in the Tour de France, Lennard Zinn tackled that
question today:
http://tour-de-france.velonews.com/article/80552/technical-qa-with-lennard-zinn---bikes-at-the-tour
Regards,
Anthony
Peter Cole
Because frames are so short. You can see from the current fashion of
very short chainstays that there is a goal of making the bike short. I
think it's to make a bike look & feel "racy". Personally, I find the
short chainstays more of a problem (tall=wheelie bike), as the "tiller
length" of the bars (long, zero or even negative for swept bars) doesn't
seem to make much difference. The effect of wheelbase on "agility" is
often touted, especially in off-road, but I think it's over-stated.
There's some effect, but mostly at low speed, where toe overlap is a
worse problem. The only real negative I've had with long stems is having
one fatigue and fail when I used it with aerobars. Fewer frame sizes
made/stocked means that if you size for the short torso you can still
fit the long torso with a long stem. Pretty much the same argument for
"compact" frames.
jim beam
> On Sun, 20 Jul 2008 17:26:23 -0500, A Muzi <a...@yellowjersey.org>
> wrote:
>
>>> So why are stems so long?
>> Adjust as you wish to your own set of criteria, there are lots of
>> products now. Long, short, track, tall, whatever. Plus adapters.
>
>
> stretch
eh? why don't you use a longer seat post? that achieves "leg stretch".
> but that usually gives me a longer top tube. So, I use stems
> in the 60-75 range normally.
see above - then you'll get a more useful top tube length. and less
chance of emasculation if you have to step forward of the saddle
unexpectedly.
>
> In the old days, before people rode frames that were too small for
> them with seat posts way too high ('cause it looks kuel), the best way
> to get a good aero position was a long stem that pulled you down.
>
> The stability discussions (old wives tales) don't take into account a
> myriad of other factors, such as top tube length/head angle, fork
> rake, etc. Pick a stem that puts you where you want to be on the seat
> and over the cranks - with the arm stretch and aero position that
> works for how *you* normally ride. MOdify as needed.
jim beam
well, i've actually bothered to test compact frames, long term, and i
have no problems with fit. in fact, i think they're a great idea.
why do people complain about stuff they don't use? do you complain
about uncomfortable womens underwear?
A Muzi
> why do people complain about stuff they don't use? do you complain
> about uncomfortable womens underwear?
As long as I can get her out of them, no!
--
Andrew Muzi
<www.yellowjersey.org/>
Open every day since 1 April, 1971
Tom Sherman
> jim beam wrote:
>> why do people complain about stuff they don't use? do you complain
>> about uncomfortable womens underwear?
>
> As long as I can get her out of them, no!
POTW.
--
Tom Sherman - Holstein-Friesland Bovinia
"People who had no mercy will find none." - Anon.
jim beam
> On Wed, 23 Jul 2008 18:51:46 -0700, jim beam
> <spamv...@bad.example.net> wrote:
>
>> still just me wrote:
>
>>> I'm with Andrew. Noting that I'm retro - I like a taller frame for leg
>>> stretch
>> eh? why don't you use a longer seat post? that achieves "leg stretch".
>
eh? that's not true. you have many more choices in retro land for
risen stems than you do in threadless steerer land.
> so it
> leaves me with the bars much lower than the seat. That doesn't work
> for me.
>
>>> but that usually gives me a longer top tube. So, I use stems
>>> in the 60-75 range normally.
>> see above - then you'll get a more useful top tube length. and less
>> chance of emasculation if you have to step forward of the saddle
>> unexpectedly.
>
> Agreed on the top tube, but not practical per above.
rubbish. see above.
> As for the
> emasculation, that's an old wives tale.
maybe your family jewels aren't worth worrying about, but that doesn't
mean you can project your own situation onto everybody else.
> For it to have any impact at
> all you'd need to be going very slow and attempt to hop off the seat
> to straddle the bar. The odds of being in an accident situation where
> the height of the top tube actually makes a difference are very, very
> low. Most of the time you'll be headed off the bike,
gross exaggeration...
> not into a
> standing position straddling the bars.
rubbish. you need to ride off road now and then - that's why low top
tubes are such a priority with the mtb crowd.
pm
> On Thu, 24 Jul 2008 19:24:46 -0700, jim beam
>
> <spamvor...@bad.example.net> wrote:
> >eh? that's not true. you have many more choices in retro land for
> >risen stems than you do in threadless steerer land.
>
> - unless you're talking about the steel clunkers they had on banana
> seat bikes and similar. The amount of stem you can have elevated above
> the head nut is typically about 75mm, give or take. Most seats are
> 60mm high already on top of the post. If you raise up the seat at all
> you will soon be far higher than the stem will go.
I see plenty of riser quilled aluminum stems in the used bins at the
local shops.
A few seconds' googling turns up
http://www.amazon.com/Delta-Rise-Quill-Bicycle-Stem/dp/B000FHD93I
which is painted black with a pop top, so it doesn't _look_ vintage,
but it'll work.
One could pay extra for a stem that looks the vintage part:
http://www.rivbike.com/products/list/handlebars_stems_and_tape?page=2#product=16-100
http://www.rivbike.com/products/list/handlebars_stems_and_tape?page=2#product=16-131
Adjusting stem height in the threadless world is a right PITA, you
must undo 3x as many screws and deal with loose spacers. And most
shops cut the steer tube short and only put spacers below where they
set the stem. Looks sleek, but if you want to raise it up you have
nothing to clamp to.
Ryan Cousineau
still just me <wheeledB...@yahoo.com> wrote:
> On Thu, 24 Jul 2008 19:24:46 -0700, jim beam
> <spamv...@bad.example.net> wrote:
>
> >eh? that's not true. you have many more choices in retro land for
> >risen stems than you do in threadless steerer land.
>
> Oh contraire - I've never seen a vintage stem that wasn't a drop stem
> - unless you're talking about the steel clunkers they had on banana
> seat bikes and similar. The amount of stem you can have elevated above
> the head nut is typically about 75mm, give or take. Most seats are
> 60mm high already on top of the post. If you raise up the seat at all
> you will soon be far higher than the stem will go.
Well, vintage is one thing. The Nitto Technomic is quite another:
http://www.peterwhitecycles.com/stems.asp
16cm of elevation. It may well be the tallest quill stem available, but
it is widely available. Some of the adjustable stems may be able to go a
tad taller.
On the threadless side, there's always the Look Ergostem.
--
Ryan Cousineau rcou...@gmail.com http://www.wiredcola.com/
"In other newsgroups, they killfile trolls."
"In rec.bicycles.racing, we coach them."
A Muzi
>> eh? that's not true. you have many more choices in retro land for
>> risen stems than you do in threadless steerer land.
still just me wrote:
> Oh contraire - I've never seen a vintage stem that wasn't a drop stem
> - unless you're talking about the steel clunkers they had on banana
> seat bikes and similar. The amount of stem you can have elevated above
> the head nut is typically about 75mm, give or take. Most seats are
> 60mm high already on top of the post. If you raise up the seat at all
> you will soon be far higher than the stem will go.
Semantic problem maybe, but technically not quite.
Depends on whether "retro" means Italian stems made long ago or stems to
fit classic threaded forks in quill format.
Classic Italian stems and copies are uniformly 85mm from HS locknut to
bars. A classic standard quill stem may be easily swapped for an angled
stem or a taller one. Choices abound, from below locknut (track stems)
to about 225mm (adjustable stem set at 0 degrees) above locknut. User
may quickly change height within a range without disturbing headset bearing.
Threadless have technical limits to height and angle, although extenders
may be used between stem and fork in some cases.