Longtitudinal saddle position

DavidR said:

I am trying to buy a replacement stem for a friend that
has changed his drops for butterflies and agonising
over the correct size. It is on a Galaxy which has a
110mm stem. The butterfly shape takes it +70 -100 mm
from the stem.

St John's Street has 150mm and 175mm stems. I am worried
about getting a 150 in case it is still too short.

I don't have experience of butterfly bars but I wouldn't
expect such a long stem to be required, necessarily, despite
the bars having a negative reach, as a more upright position
is bound to be desired. Stems longer than 140mm are unusual
on any kind of bike with any kind of bars. You have to start
worrying about flex and strength once you get beyond that.

In any case, you might want to consider the double-
articulated Look ErgoStem. Expensive and heavy but extremely
versatile. Reach goes up to 160mm (when rise is zero). A
shim will be required for 25.4 bars.

Quoted message said:

My inclination is to go for the 175 and move the saddle
forward if it is too long .

My friend then showed me all the books that that say the
saddle should be set so that there is a plumb line between
knee and pedal.

That's rubbish. Search the web for "The myth of KOPS", etc.
However, it is important that the saddle should be set for
comfortable seating and pedalling (that's usually back a
bit, whatever the stem is), not adjusted to correct reach to
the bars. That's what the top tube, stem and bars are for.

~PB

Quoted post said:

Originally posted by Davidr
My friend then showed me all the books that that say the saddle should be set so that there is a plumb line between knee and pedal. Eh? All I have ever done is move the saddle so that I sit on it properly.
...do others put much score on the business of longitudinal position?

Yeah, I'd second what Pete Biggs wrote about the KOPS (Knee Over Pedal Spindle) business. Lots of people advocate this as being critical to effective cycling performance, but I'd take comfort any day.

Saddle position is important from a comfort point of view. There are lots of bizarre formulae out there that will dictate how you "should" set up your bike. I doubt you'd get a consistent answer if you tried each and every one of them.

As for a 175mm stem - that seems overlong to me for a roadbike frame. I only use a 130mm quill stem (just cannot bring myself to give up my 631c steel frame), but I haven't seen may stems that go beyond the 140mm length on the Ahead designs.

"DavidR" <[email hidden]> wrote in message news:<[email hidden]>...

Quoted message said:

snipped My friend then showed me all the books that that
say the saddle should be set so that there is a plumb line
between knee and pedal. Eh? All I have ever done is move
the saddle so that I sit on it properly.

I have gone and checked my bikes. I have a tourer with the
saddle fully back and according to the plumb it is about
30mm too far forward. My mtb has a longer frame so the
saddle is slightly further forward with consequent
different relationship with the BB.

peterwhitecycles.comfitting.htmOpen ↗ The above
article bike fitting by Peter White, a USA cycle dealer is
the best I,ve seen on bike fit. The section on fore/aft
saddle position is pasted below. " Fore-Aft Saddle Position

Now we get to what I think is the most important part of
fitting a bicycle, the fore-aft position of the saddle.
Once you get this right, everything else is easy. This
position is determined more by how you intend to use your
bike than by anything else. If you look at a typical bike,
the saddle is behind the crank center, or bottom bracket.
There's a frame tube (the seat tube) running from the
cranks to the saddle, and it's at an angle. That angle
partly determines the fore-aft position of the saddle
relative to the cranks and pedals. That fore-aft position
determines how your body is balanced on the bicycle. Your
balance determines how comfortable you are, and how
efficiently you can pedal the bike.

Stand up straight in front of a mirror and turn to the
side. Look at yourself in the mirror. When standing
straight your head, hands, seat and feet are all fairly
close to being in line with each other. Now bend over at
the waist. Notice that not only has your head moved to a
position ahead of your feet, but your rear end has moved
behind your feet. If this were not the case, you would fall
forward. Your seat moves back when you bend at the waist to
keep you in balance.

Your torso needs to be leaning forward for two reasons;
power output and aerodynamics. With an upright torso, you
can't use the gluteus muscles to good effect. Also, you
can't effectively pull up on the handlebar from an upright
position. An upright torso is also very poor
aerodynamically. When cycling on level ground, the majority
of your effort goes against wind resistance. The easier it
is for your body to move through the air, the less work
you'll have to do. With your torso closer to horizontal, you
present less frontal surface to the air and don't have to
work as hard to maintain a given speed.

Obviously, the most aerodynamically efficient position may
not be the most pleasant position to be in for several hours
on a cross country tour. So there's a tradeoff. As you move
to a more horizontal position, the saddle needs to be
positioned further to the rear to maintain your body's
balance, just as your rear end moves to the rear as you bend
over while standing. It so happens that racers are more
inclined to use a horizontal torso position than tourers,
and racers are more concerned with having the handlebars
further forward to make climbing and sprinting out of the
saddle more effective."

cheers Iain

DavidR said:

I am trying to buy a replacement stem for a friend that
has changed his drops for butterflies and agonising
over the correct size. It is on a Galaxy which has a
110mm stem. The butterfly shape takes it +70 -100 mm
from the stem.

St John's Street has 150mm and 175mm stems. I am worried
about getting a 150 in case it is still too short. My
inclination is to go for the 175 and move the saddle
forward if it is too long .

My friend then showed me all the books that that say the
saddle should be set so that there is a plumb line between
knee and pedal. Eh? All I have ever done is move the
saddle so that I sit on it properly.

This has more or less been shown to be balderdash. Basically
move it until the pedalling action feels right. If you're
constantly pushing your bum back to try and get a bit more
power on the flat (you'll always have to do this uphill),
the seat needs to go back.

Then, and only then, go and buy the right length stem!

"Pete Biggs" <[email hidden]> wrote

Quoted message said:

DavidR said:

I am trying to buy a replacement stem for a friend that
has changed his drops for butterflies and agonising
over the correct size. It is on a Galaxy which has a
110mm stem. The butterfly shape takes it +70 -100 mm
from the stem.

St John's Street has 150mm and 175mm stems. I am worried
about getting a 150 in case it is still too short.

I don't have experience of butterfly bars but I wouldn't
expect such a long stem to be required, necessarily,
despite the bars having a negative reach, as a more
upright position is bound to be desired. Stems longer than
140mm are unusual on any kind of bike with any kind of
bars. You have to start worrying about flex and strength
once you get beyond that.

A butterfly has over 800mm of pipe. I doubt stem flex would
get much look in!

Quoted message said:

Quoted message said:

My inclination is to go for the 175 and move the saddle
forward if it is too long .

My friend then showed me all the books that that say the
saddle should be set so that there is a plumb line
between knee and pedal.

That's rubbish. Search the web for "The myth of
KOPS", etc.

Before I read this I had exactly the same thoughts (that is,
the rotation around the BB being independant of gravity).

Quoted message said:

However, it is important that the saddle should be set
for comfortable seating and pedalling (that's usually
back a bit, whatever the stem is), not adjusted to
correct reach to the bars. That's what the top tube, stem
and bars are for.

The thing is that it is the saddle that is adjustable. You
can have the frame in any length as long as it is 560mm.
Stems are expensive. If stem length is changed it seems
worth getting a big difference and making the fine
adjustment with the saddle. I see the 150 stem as leaving no
room for error (although the extra height will make up some
of the difference). If the 175 is too long, the saddle only
needs to move by 20mm.

I haven't been talked out of the longer stem yet but I am
still very undecided.

DavidR said:

The thing is that it is the saddle that is adjustable.

It is adjustable but you should adjust it only for the
correct reason........

Quoted message said:

You can have the frame in any length as long as it is
560mm. Stems are expensive.

Decent quality stems can be bought for less than £15 and
some money can be recouped from any unsuitable ones by
selling them on (might even find a friendly bike shop that
would lend some or try fitting various stems in the shop).
Alternatively, there are adjustable stems, which are indeed
expensive but at least provide lots of scope and therefore
peace of mind.

Quoted message said:

If stem length is changed it seems worth getting a big
difference and making the fine adjustment with the saddle.

That would be a big mistake. Saddle longitudinal position
has more important effects than the reach to the bars. Even
a small difference in saddle position will affect saddle
comfort and pedalling efficiency, regardless of handlebar
stem. It's about angle of legs to pedals and tilt of
pelvis, etc.

A 10mm difference in stem length is quite significant.
You've got to be very careful when making changes bigger
than this, although I understand the difficulty when
changing to a different type of bars. There's similar
trouble when building a new bike with a different size/shape
frame from what one is used to. That's why I suggest
considering an adjustable stem - even if it would eventually
be replaced with an ordinary one - you'd at least be able to
experiment and discover what extension and rise works.

With a fixed stem though, when it comes to the final
adjustment, careful fine tuning of the height can make the
bars feel comfortable for whatever reach you have when reach
is within 5 to 10mm of "correct". It's better to do this
than adjust the saddle, IMO.

I know it's all a lot of trouble (been there done that) but
it's worth it in the end.

Quoted message said:

I see the 150 stem as leaving no room for error
(although the extra height will make up some of the
difference). If the 175 is too long, the saddle only
needs to move by 20mm.

ONLY!!!! Even 2 to 5mm makes a difference to pedalling
position, let alone 20.

~PB

"Pete Biggs" <[email hidden]> wrote in
message -"]news:[email hidden]-
berlin.de... <snip>

Quoted message said:

Quoted message said:

I see the 150 stem as leaving no room for error
(although the extra height will make up some of the
difference). If the 175 is too long, the saddle only
needs to move by 20mm.

ONLY!!!! Even 2 to 5mm makes a difference to pedalling
position, let alone 20.

Well, Pete, all I can say is you must very much in tune with
your innerself - no, sorry, _outer_ self 🙂 - I had a pair
of butterfly bars and played around with saddle position,
stem length, bar angle etc - and although some positions
were more comfortable than others and I eventually settled
on a particular arrangement, I can't honestly say that I
noticed a difference of as little as 2 - 5mm in any setting
as offering a significant benefit in terms of comfort or
pedalling ability. I have certainly not noticed lateral
adjustment of the saddle by those sort of distances making
any difference. In terms of the bars, I found whatever
change meant a trade off of one thing against another,
getting the 'right' position was mainly just a balancing act
and highly subjective, and, at the margins, impossible to
say whether one setting was really better than another. In
the end I just gave up trying to find the optimal setting
(and gave up with the bars as well).

Rich

On Thu, 18 Mar 2004 21:14:16 -0000, "DavidR" <[email hidden]>

wrote in message : said:

Quoted message said:

That's rubbish. Search the web for "The myth of
KOPS", etc.

AASHTA: <url:http://www.sheldonbrown.com/kops.html>

--
Guy
===
May contain traces of irony. Contents liable to settle after
posting. chapmancentral.co.ukchapmancentral.co.ukOpen ↗

88% of helmet statistics are made up, 65% of them at
Washington University

Richard Goodman said:

Quoted message said:

Quoted message said:

I see the 150 stem as leaving no room for error
(although the extra height will make up some of the
difference). If the 175 is too long, the saddle only
needs to move by 20mm.

ONLY!!!! Even 2 to 5mm makes a difference to pedalling
position, let alone 20.

Perhaps I should have inserted a "can" in there.

Quoted message said:

Well, Pete, all I can say is you must very much in tune
with your innerself - no, sorry, _outer_ self 🙂 - I had
a pair of butterfly bars and played around with saddle
position, stem length, bar angle etc - and although some
positions were more comfortable than others and I
eventually settled on a particular arrangement, I can't
honestly say that I noticed a difference of as little as
2 - 5mm in any setting as offering a significant benefit
in terms of comfort or pedalling ability. I have
certainly not noticed lateral adjustment of the saddle by
those sort of distances making any difference. In terms
of the bars, I found whatever change meant a trade off of
one thing against another, getting the 'right' position
was mainly just a balancing act and highly subjective,
and, at the margins, impossible to say whether one
setting was really better than another. In the end I just
gave up trying to find the optimal setting (and gave up
with the bars as well).

I appreciate that different people are sensitive to
different amounts of variation (although the amounts can
lessen as one becomes closer to the ideal position*) but I
think the principle is still good: set saddle so it's
right for pedalling then worry about reach to bars
afterwards. In the OP's case, the compensation required
could end up even more than the quoted 20mm (and I think
20mm is dodgy enough).

Personally, I was experimenting just the other day with a
new saddle and found 5mm adjustments made a significant
difference to how comfortable my outer self felt! And I've
previously experimented with simultanous stem and saddle
settings: saddle forwards 10mm with stem longer by 10mm does
not feel the same as saddle and stem back by 10mm.

Another factor that we've forgotten to mention is steering
and handling. Things can get weird when the stem is
extremely long: sluggish steering and pedalling whilst
standing may become awkward.

* If you're way out to start with, with any factor (saddle
height/reach/whatever), then yes 5 or even 10mm might not
even be noticeable at all, but when you've settled on what
feels like an almost perfect position and have become used
to it, even a 2mm difference can result in either an
improvement or discomfort... in my experience anyway.

~PB

Quoted post said:

Originally posted by Pete Biggs
Richard Goodman wrote:

I appreciate that different people are sensitive to different amounts of variation (although the amounts can lessen as one becomes closer to the ideal position*) but I think the principle is still good: set saddle so it's right for pedalling then worry about reach to bars afterwards. In the OP's case, the compensation required could end up even more than the quoted 20mm (and I think 20mm is dodgy enough).

Personally, I was experimenting just the other day with a new saddle and found 5mm adjustments made a significant difference to how comfortable my outer self felt! And I've previously experimented with simultanous stem and saddle settings: saddle forwards 10mm with stem longer by 10mm does not feel the same as saddle and stem back by 10mm.

Another factor that we've forgotten to mention is steering and handling. Things can get weird when the stem is extremely long: sluggish steering and pedalling whilst standing may become awkward.

* If you're way out to start with, with any factor (saddle height/reach/whatever), then yes 5 or even 10mm might not even be noticeable at all, but when you've settled on what feels like an almost perfect position and have become used to it, even a 2mm difference can result in either an improvement or discomfort... in my experience anyway.

~PB

I'm curious as to how you are moving the stem backwards and forwards. Is this something that you can do on the Ahead system? Or do you have lots of stems that you swap in and out until you get the position just right?

McBain_v1 said:

I'm curious as to how you are moving the stem backwards
and forwards. Is this something that you can do on the
Ahead system? Or do you have lots of stems that you swap
in and out until you get the position just right?

I did mean by either changing stems or using a special
adjustable stem* (I've done both). This isn't specific to
the ahead system. One extra method that is, though, is
refitting the stem upside down. This can provide a slightly
different reach as well as rise, depending on the stem's
angle, so you effectively get two stems in one.

Changing stems is quite quick and easy if the stem is a front-
opening type so the lever and bar tape doesn't need redoing
each time.

* egs. Look ErgoStem, Giant, Kalloy.

~PB

Quoted post said:

Originally posted by Pete Biggs
I did mean by either changing stems or using a special
adjustable stem* (I've done both). This isn't specific to
the ahead system. One extra method that is, though, is
refitting the stem upside down. This can provide a slightly
different reach as well as rise, depending on the stem's
angle, so you effectively get two stems in one.

Changing stems is quite quick and easy if the stem is a front-
opening type so the lever and bar tape doesn't need redoing
each time.

* egs. Look ErgoStem, Giant, Kalloy.

~PB

Righto! I've bought myself an Ahead adaptor just in case my quill stem breaks so I can keep riding my "old" (but new to me) frames that normally need quill stems. I like the idea of an open-face stem, it must make changing things around a lot easier. I hate having to strip the brakes and tape off one side of my bars if I have to change the stem 🙁

McBain_v1 said:

Righto! I've bought myself an Ahead adaptor just in case
my quill stem breaks so I can keep riding my "old" (but
new to me) frames that normally need quill stems.

Yes the adaptors work well - I use one on my old tourer.

Quoted message said:

I like the idea of an open-face stem, it must make
changing things around a lot easier. I hate having to
strip the brakes and tape off one side of my bars if I
have to change the stem 🙁

Absolutely. I hate that job too.

~PB

"Pete Biggs" <[email hidden]> wrote

Quoted message said:

DavidR said:

I see the 150 stem as leaving no room for error
(although the extra height will make up some of the
difference). If the 175 is too long, the saddle only
needs to move by 20mm.

ONLY!!!! Even 2 to 5mm makes a difference to pedalling
position, let alone 20.

Come come. That's no different to altering the bar height by
the same amount, according to "the myth of KOPS". Or you
could move your cleats by half that amount (think about it).

If you meant that a 5mm saddle adjustment (for a given stem)
can make the difference to getting your bum on the saddle's
sweet spot then I agree.

As I said, I have 3 bikes and KOPS was never considered.
Saddle height is the only common thing between them.

DavidR said:

"Pete Biggs" <[email hidden]> wrote

Quoted message said:

DavidR said:

I see the 150 stem as leaving no room for error
(although the extra height will make up some of the
difference). If the 175 is too long, the saddle only
needs to move by 20mm.

ONLY!!!! Even 2 to 5mm makes a difference to pedalling
position, let alone 20.

Come come. That's no different to altering the bar height
by the same amount, according to "the myth of KOPS". Or
you could move your cleats by half that amount (think
about it).

We can argue about the figures but the practice of adjusting
saddle to correct reach to the bars is bad (and that's not
just my opinion or an unusal one). I think 20mm saddle
compensation is too much. And messing about with bars and
cleats by 2 to 5mm is also significant.

Quoted message said:

If you meant that a 5mm saddle adjustment (for a given
stem) can make the difference to getting your bum on the
saddle's sweet spot then I agree.

No I didn't just mean that, although perhaps my "2mm" was a
bit over the top. certainly 10mm is significant, I think,
and probably less.

Quoted message said:

As I said, I have 3 bikes and KOPS was never considered.
Saddle height is the only common thing between them.

I am not advocating KOPS.

~PB

"Pete Biggs" <[email hidden]> wrote

Quoted message said:

DavidR said:

"Pete Biggs" <[email hidden]> wrote

Quoted message said:

DavidR wrote:

Quoted message said:

Quoted message said:

Quoted message said:

> I see the 150 stem as leaving no room for error
> (although the extra height will make up some of the
> difference). If the 175 is too long, the saddle only
> needs to move by 20mm.

ONLY!!!! Even 2 to 5mm makes a difference to pedalling
position, let alone 20.

Come come. That's no different to altering the bar
height by the same amount, according to "the myth of
KOPS". Or you could move your cleats by half that amount
(think about it).

We can argue about the figures but the practice of
adjusting saddle to correct reach to the bars is bad (and
that's not just my opinion or an unusal one). I think 20mm
saddle compensation is too much.

How do we know what is correct to start with? If we don't
use KOPS then effective seat post angle has no meaning.
The only useful parameter is the linear distance between
pedal & saddle.

Quoted message said:

And messing about with bars and cleats by 2 to 5mm is also
significant.

Then how do people manage with more than one bike? Or
several bikes with one pair of shoes & cleats. Indeed,
how on earth do people manage with drop bars? On that
score, bar size & shape and height & angle hood position
& shape present far greater mysteries than a few mm in
foot position.

DavidR said:

Quoted message said:

We can argue about the figures but the practice of
adjusting saddle to correct reach to the bars is bad (and
that's not just my opinion or an unusal one). I think
20mm saddle compensation is too much.

How do we know what is correct to start with? If we don't
use KOPS then effective seat post angle has no meaning.
The only useful parameter is the linear distance between
pedal & saddle.

All I mean by "correct" here is what feels best after
experimentation. If you end up reckoning bike feels best
with saddle quite a way back, for example, it won't feel as
good with it shoved forwards 20mm but with a 20mm longer
stem, in my experience. Seat position has some effects on
pedalling and seating efficiency and comfort independent of
reach to bars, so seat angle and saddle layback is
important.

I don't believe in sticking to KOPS in terms of having to
have knee directly over pedal spindle, but KOPS +/-
personal optimum.

Quoted message said:

Quoted message said:

And messing about with bars and cleats by 2 to 5mm is
also significant.

Then how do people manage with more than one bike?

The differences are significant in terms of altering comfort
and feel - which won't feel equally quite as good on all
bikes. People manage by either enjoying the change, or
trying to equalise them and/or putting up with the
imperfection.

But when setting up a bike, getting the saddle right THEN
getting stem right is normal traditional good practice, it's
not just some fussy/wacky personal opinion of mine. That's
my only point, really. If you feel 20mm is insignificant,
then I'll agree to disagree.

~PB

"Pete Biggs" <[email hidden]> wrote

Quoted message said:

DavidR wrote:

Quoted message said:

Quoted message said:

Quoted message said:

And messing about with bars and cleats by 2 to 5mm is
also significant.

Then how do people manage with more than one bike?

The differences are significant in terms of altering
comfort and feel - which won't feel equally quite as good
on all bikes. People manage by either enjoying the change,
or trying to equalise them and/or putting up with the
imperfection.

The perfect set up is obviously impossible. Its a good thing
the body is pretty tolerant.

After further consideration, I am buying a 150mm 12degree
stem. This gives a tourer roughly similar reach & rise to a
standard mountain bike. I am hoping that the height
compensates for the butterfly's large negative offset but
not put the front too far out of reach.