Some math help please

[Bestest Handsander]

I admit it. I have an English degree, so a little help here would be
appreciated.

My bike has a 592mm reach from the tip of the saddle to the middle of the
handbar top tube. The current stem is 120mm, 84 degrees.

The Question: How much height to I gain if I flip the stem over so that it's
96 degrees from the steerer tube? Also, does flipping it over change the
reach from the tip of the saddle?

Thanks!

[Jeff Starr]

On Mon, 3 Apr 2006 21:08:52 -0600, "Bestest Handsander"
> wrote:

>I admit it. I have an English degree, so a little help here would be
>appreciated.
>
>My bike has a 592mm reach from the tip of the saddle to the middle of the
>handbar top tube. The current stem is 120mm, 84 degrees.
>
>The Question: How much height to I gain if I flip the stem over so that it's
>96 degrees from the steerer tube? Also, does flipping it over change the
>reach from the tip of the saddle?
>
>Thanks!
>

Here, take a look at this chart:
http://www.habcycles.com/fitting.html


Life is Good!
Jeff

[Michael Press]

In article >,
"Bestest Handsander" >
wrote:

> I admit it. I have an English degree, so a little help here would be
> appreciated.
>
> My bike has a 592mm reach from the tip of the saddle to the middle of the
> handbar top tube. The current stem is 120mm, 84 degrees.
>
> The Question: How much height to I gain if I flip the stem over so that it's
> 96 degrees from the steerer tube? Also, does flipping it over change the
> reach from the tip of the saddle?

What is the head tube angle, beta?

2 * 120 * sin(6 deg) * sin beta.

Suppose beta = 70, 71, 72, 73 deg
then the increment is
23.6, 23.7, 23.9, 24.0 mm.

What is the name of Lady Macbeth's dog?

--
Michael Press

[Road Man]

I think the rise will be about 25 mm, and the travel backwards about 5
mm. I wouldn't be concerned about the 5 mm, it's small and in the
direction of more comfort.

The solution is left as an exercise for the students. Be prepared for
a pop quiz.

Ken


"Michael Press" > wrote in message
...
> In article >,
> "Bestest Handsander" >
> wrote:
>
>> I admit it. I have an English degree, so a little help here would
>> be
>> appreciated.
>>
>> My bike has a 592mm reach from the tip of the saddle to the middle
>> of the
>> handbar top tube. The current stem is 120mm, 84 degrees.
>>
>> The Question: How much height to I gain if I flip the stem over so
>> that it's
>> 96 degrees from the steerer tube? Also, does flipping it over
>> change the
>> reach from the tip of the saddle?
>
> What is the head tube angle, beta?
>
> 2 * 120 * sin(6 deg) * sin beta.
>
> Suppose beta = 70, 71, 72, 73 deg
> then the increment is
> 23.6, 23.7, 23.9, 24.0 mm.
>
> What is the name of Lady Macbeth's dog?
>
> --
> Michael Press

[Werehatrack]

On Mon, 3 Apr 2006 21:08:52 -0600, "Bestest Handsander"
> wrote:

>I admit it. I have an English degree, so a little help here would be
>appreciated.
>
>My bike has a 592mm reach from the tip of the saddle to the middle of the
>handbar top tube.

Irrelevant.

>The current stem is 120mm, 84 degrees.

But what's the head tube angle?

>The Question: How much height to I gain if I flip the stem over so that it's
>96 degrees from the steerer tube?

One point off for the assertion of having a degree in English, and
then committing a spelling error.

Without a precise head tube angle, this question can't be accurately
answered. However, for purposes of approximation, taking 72 degrees
as a likely figure, then the stem's angle above horizontal is changed
from 14 degrees to 22 degrees by the flip; the vertical change is then
((120 x sin(22))-(120 x sin(14)))mm, which is about 15mm of elevation.
The change in the horizontal position is only about 5mm. Neither of
these is a large value, though 15mm of additional bar height could be
enough to feel.

>Also, does flipping it over change the
>reach from the tip of the saddle?

As noted, yes, by a negligible 5mm.

--
Typoes are a feature, not a bug.
Some gardening required to reply via email.
Words processed in a facility that contains nuts.

[Mike]

Werehatrack wrote:
> On Mon, 3 Apr 2006 21:08:52 -0600, "Bestest Handsander"
> > wrote:
>
> >I admit it. I have an English degree, so a little help here would be
> >appreciated.
> >
> >My bike has a 592mm reach from the tip of the saddle to the middle of the
> >handbar top tube.
>
> Irrelevant.
>
> >The current stem is 120mm, 84 degrees.
>
> But what's the head tube angle?
>
> >The Question: How much height to I gain if I flip the stem over so that it's
> >96 degrees from the steerer tube?
>

>The answer is Tuesday, the 29th
> One point off for the assertion of having a degree in English, and
> then committing a spelling error.
>
> Without a precise head tube angle, this question can't be accurately
> answered. However, for purposes of approximation, taking 72 degrees
> as a likely figure, then the stem's angle above horizontal is changed
> from 14 degrees to 22 degrees by the flip; the vertical change is then
> ((120 x sin(22))-(120 x sin(14)))mm, which is about 15mm of elevation.
> The change in the horizontal position is only about 5mm. Neither of
> these is a large value, though 15mm of additional bar height could be
> enough to feel.
>
> >Also, does flipping it over change the
> >reach from the tip of the saddle?
>
> As noted, yes, by a negligible 5mm.
>
> --
> Typoes are a feature, not a bug.
> Some gardening required to reply via email.
> Words processed in a facility that contains nuts.

[Bestest Handsander]

"Werehatrack" > wrote in message
...
> On Mon, 3 Apr 2006 21:08:52 -0600, "Bestest Handsander"
> > wrote:
>
>>I admit it. I have an English degree, so a little help here would be
>>appreciated.
>>
>>My bike has a 592mm reach from the tip of the saddle to the middle of the
>>handbar top tube.
>
> Irrelevant.
>
>>The current stem is 120mm, 84 degrees.
>
> But what's the head tube angle?
>
>>The Question: How much height to I gain if I flip the stem over so that
>>it's
>>96 degrees from the steerer tube?
>
> One point off for the assertion of having a degree in English, and
> then committing a spelling error.
>
> Without a precise head tube angle, this question can't be accurately
> answered. However, for purposes of approximation, taking 72 degrees
> as a likely figure, then the stem's angle above horizontal is changed
> from 14 degrees to 22 degrees by the flip; the vertical change is then
> ((120 x sin(22))-(120 x sin(14)))mm, which is about 15mm of elevation.
> The change in the horizontal position is only about 5mm. Neither of
> these is a large value, though 15mm of additional bar height could be
> enough to feel.
>
>>Also, does flipping it over change the
>>reach from the tip of the saddle?
>
> As noted, yes, by a negligible 5mm.
>
> --
> Typoes are a feature, not a bug.
> Some gardening required to reply via email.
> Words processed in a facility that contains nuts.

LOL! Perhaps I should specify it was English Lit. Never was a good speller.
Headtube is 74 degrees, but the numbers you and the others provided are
close enough for my purposes.

Thanks all.

[Zog The Undeniable]

Bestest Handsander wrote:

> I admit it. I have an English degree, so a little help here would be
> appreciated.
>
> My bike has a 592mm reach from the tip of the saddle to the middle of the
> handbar top tube. The current stem is 120mm, 84 degrees.
>
> The Question: How much height to I gain if I flip the stem over so that it's
> 96 degrees from the steerer tube? Also, does flipping it over change the
> reach from the tip of the saddle?

I have an engineering degree, but I'd just flip the stem and see what
happens. It would probably be quicker :-)

[Mike Reed]

Werehatrack wrote:
> >Also, does flipping it over change the
> >reach from the tip of the saddle?
>
> As noted, yes, by a negligible 5mm.

For me, that 5mm, while small, was enough to finish off my bike fit. A
year ago, I moved 15mm worth of spacers from below the stem to above
it, and flipped the stem. This gave me the same elevation, but got me
an "in between" stem length :) It feels just about perfect now.

-Mike

[Bestest Handsander]

"Zog The Undeniable" > wrote in message
news:4432a325.0@entanet...
> Bestest Handsander wrote:
>
>> I admit it. I have an English degree, so a little help here would be
>> appreciated.
>>
>> My bike has a 592mm reach from the tip of the saddle to the middle of the
>> handbar top tube. The current stem is 120mm, 84 degrees.
>>
>> The Question: How much height to I gain if I flip the stem over so that
>> it's 96 degrees from the steerer tube? Also, does flipping it over change
>> the reach from the tip of the saddle?
>
> I have an engineering degree, but I'd just flip the stem and see what
> happens. It would probably be quicker :-)

Don't have it. Trying to figure out exactly what stem I need. Although I
start cutting one out of paper, but the kids distracted me and by the time I
got back to it, people had already posted the info I needed.

Thanks again

[David L. Johnson]

On Tue, 04 Apr 2006 17:43:28 +0100, Zog The Undeniable wrote:

>> The Question: How much height to I gain if I flip the stem over so that it's
>> 96 degrees from the steerer tube? Also, does flipping it over change the
>> reach from the tip of the saddle?
>
> I have an engineering degree, but I'd just flip the stem and see what
> happens. It would probably be quicker :-)

I have a couple of math degrees, and that was going to be my suggestion as
well. it is possible to compute it, but it would be a PITA.

--

David L. Johnson

__o | And what if you track down these men and kill them, what if you
_`\(,_ | killed all of us? From every corner of Europe, hundreds,
(_)/ (_) | thousands would rise up to take our places. Even Nazis can't
kill that fast. -- Paul Henreid (Casablanca).

[John Forrest Tomlinson]

On Tue, 04 Apr 2006 22:53:42 -0400, "David L. Johnson"
> wrote:

>On Tue, 04 Apr 2006 17:43:28 +0100, Zog The Undeniable wrote:
>
>>> The Question: How much height to I gain if I flip the stem over so that it's
>>> 96 degrees from the steerer tube? Also, does flipping it over change the
>>> reach from the tip of the saddle?
>>
>> I have an engineering degree, but I'd just flip the stem and see what
>> happens. It would probably be quicker :-)
>
>I have a couple of math degrees, and that was going to be my suggestion as
>well. it is possible to compute it, but it would be a PITA.

And another approach would be to get a big piece of paper, a ruler and
a protractor and draw it very carefully -- perhaps using a scale of
1cm to 1in or 1:2 to make if needed to fit on the paper.

JT


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[Alex Rodriguez]

In article >,
says...
>
>
>On Tue, 04 Apr 2006 22:53:42 -0400, "David L. Johnson"
> wrote:
>
>>On Tue, 04 Apr 2006 17:43:28 +0100, Zog The Undeniable wrote:
>>
>>>> The Question: How much height to I gain if I flip the stem over so that
it's
>>>> 96 degrees from the steerer tube? Also, does flipping it over change the
>>>> reach from the tip of the saddle?
>>>
>>> I have an engineering degree, but I'd just flip the stem and see what
>>> happens. It would probably be quicker :-)
>>
>>I have a couple of math degrees, and that was going to be my suggestion as
>>well. it is possible to compute it, but it would be a PITA.
>
>And another approach would be to get a big piece of paper, a ruler and
>a protractor and draw it very carefully -- perhaps using a scale of
>1cm to 1in or 1:2 to make if needed to fit on the paper.

You can also check out http://www.habcycles.com/fitting.html . Someone's
done all the work for you.
---------------
Alex