Reach

On 23/12/15 07:55, Sir Ridesalot wrote:

snip

I alsways thought that REACH was the distance one had to reach in
order to grip the handlebar. Thus headtube angle, seattube angle,
stem length and seatpost setback all affected the REACH. Now it seems
as if REACH is smoething entirely different that only complicates
things.

It might just be semantics. In;

http://cyclingabout.com/understandin...rame-geometry/

The reach is clearly defined as from the bottom bracket to the top head
tube center[1]. Not terribly useful imho.

However, the same site defines the top tube horizontal length, which is
what *I* would call reach. The former is affected by seat tube angle,
the latter not. However, if you have a small frame with a long seat
tube, you're back to square one!

[1]Which does seem to be the common definition.

https://www.google.co.uk/search?q=bi...Hb3GAWEQsAQIOg

On 12/19/2015 10:38 AM, AMuzi wrote:
On 12/19/2015 12:23 PM, wrote:
Is reach the distance from center of BB horizontal, to the center of
the Head Tube horizontal? Or is the center of the head tube at the top?

Mark Cleary.


Good question. We used to use 'reach' for center of post to center of
bars, horizontally.

That made sense. At least in the past. Then the old "reach" was abused
by using various techniques to use a smaller number of frame sizes to
fit a larger number of riders, while achieving the same "reach.'

The newer meaning is on a horizontal line from BB center to center of
head tube at the top. It's used with another newish term, 'stack', see
image:

The new definition of reach is redundant to other frame measurements,
though not useless. They should have come up with a new term for it, not
redefined an old term.

On Tue, 22 Dec 2015 22:55:37 -0800 (PST), Sir Ridesalot
wrote:

On Tuesday, December 22, 2015 at 10:38:13 PM UTC-5, John B. wrote:
On Tue, 22 Dec 2015 23:52:30 +0000, Clive George
wrote:

On 22/12/2015 23:01, John B. wrote:
On Tue, 22 Dec 2015 01:00:51 +0000, Clive George
wrote:

On 21/12/2015 23:50, John B. wrote:
You do need to consider the relative position of all three.

I did... I do :-)

Again, if the BB is a constant distance from the head tube, i.e.
constant Reach and you alter the top tube length, by altering the seat
tube angle you have not altered the Reach although you have altered,
perhaps radically, the distance from the seat to the handle bars.

And? I did say you need the other distances to the saddle too.

If you assume a bike with a sloped top tube you can have a constant
Stack measurement with a large difference in the actual distance from
the seat to the pedals.

Slope or otherwise of top tube doesn't matter.

So, if it is possible to have a range of how the bike actually fits
with a constant Stack and Reach dimension then what information does
the Reach and Stack provide?

The relative position of your feet and hands.

Nope. A bike with the exact same Stack and Reach measurements can have
substantially different distances from the seat to the handle bars and
from the seat to the bottom bracket.

Um, this is a pretty bad reading of what I wrote. I said reach and stack
provide the relative position of feet and hands and you say "Nope" then
start talking about relative position of bum/seat to those?

Rephrase your answer to "Yep" and I'll accept it.

Combine with a seat-tube
angle and your leg length, and you've got the lot. Angles are similar
for similar types of bikes, your leg length is going to be fixed, so
actually assuming you're buying a "road bike" or a "tt bike", you're
going to know the lot with just reach and stack.

Yes, I did point out that there was a substantial difference between
the usual road bike and a Tri or Time Trial bike. But as I also
pointed out there is no indication of the distance from the seat to
the handle bars using only the Stack and Reach dimensions as they are
measured from the BB, where you feet are, not the seat where your butt
is.

But if you know the angle of the seat tube, which for a road and TT bike
are going to be predictable, you get the rest of the information - your
leg length is the other variable.

Obviously if you're doing less-mainstream bikes, you need more detail,
but for buying a fairly normal racing bike, you don't.

Or you could try this explanation :

http://www.cervelo.com/en/engineerin...y-and-fit.html


Yup. I read it and it appears that you need the Stack and Reach
dimensions and then you need the chart to refer to...

But just go down to your friendly Local Bike Shop and measure some
framed. Reach is the measurement from a vertical line through the BB
to the top of the head tube. Stack is the measurement from a
horizontal line through the BB to the top of the head tube.

Find a normal road bike and measure the Stack and Reach. Then have a
look at a top of the line Tri or Time Trial bike and you may find that
the Stack and Reach are essentially the same as the road bike.

Have you done this? I think not...

Look at the Cervelo bikes - here's the specs of their R3 (road) and P3
(TT) bikes

http://www.cervelo.com/media/docs/R3...7652f024-0.pdf

http://www.cervelo.com/media/docs/P3...ceb5e22f-1.PDF

The reach and stack on the TT bike is not similar to the road bike. They
are different. I'm afraid your hypothesis is false.

Note also that Cervelo don't just specify reach/stack - see the PDFs.

Then sit on them and you will discover that while the Stack and Reach
are the same on both bikes your position on one bike will be much,
much different then on the other.


No what I wrote is correct.

If you were to use the Stack and Reach measurements to select a bike
you would have very different sizes.

The P3 (size 54) has a Reach of 411, the R3 (size 54) has a reach of
378. Or, a P3 with a 378 Reach (375 actually) is a size 45

Which is what I've been saying, that the Stack - Reach measurements
are essentially a meaningless measurement.

You'd need to know the stack/reach combo which is good for you on a road
bike, and the equivalent on a TT bike, but once you've done that you're
sorted.

Obviously. Just as I would need to know the top tube length for a road
and TT bike, which I can measure with a tape measure.

So what is this Reach and Stack measurement - which is difficult to
measure - telling me that the traditional measurements don't?

Or to put it another way. What good are they?
--
cheers,

John B.

I alsways thought that REACH was the distance one had to reach in order to grip the handlebar. Thus headtube angle, seattube angle, stem length and seatpost setback all affected the REACH. Now it seems as if REACH is smoething entirely different that only complicates things.

Cheers

They have invented a new measurement. the "New" Reach is the
horizontal distance from a vertical line through the bottom bracket to
the head tube. They have also invented a "Stack" measurement that is a
vertical measurement from a horizontal line through the bottom bracket
to the top of the head tube.
--
cheers,

John B.

On Wednesday, December 23, 2015 at 5:57:28 AM UTC-5, John B. wrote:
On Tue, 22 Dec 2015 22:55:37 -0800 (PST), Sir Ridesalot
wrote:

On Tuesday, December 22, 2015 at 10:38:13 PM UTC-5, John B. wrote:
On Tue, 22 Dec 2015 23:52:30 +0000, Clive George
wrote:

On 22/12/2015 23:01, John B. wrote:
On Tue, 22 Dec 2015 01:00:51 +0000, Clive George
wrote:

On 21/12/2015 23:50, John B. wrote:
You do need to consider the relative position of all three.

I did... I do :-)

Again, if the BB is a constant distance from the head tube, i.e.
constant Reach and you alter the top tube length, by altering the seat
tube angle you have not altered the Reach although you have altered,
perhaps radically, the distance from the seat to the handle bars.

And? I did say you need the other distances to the saddle too.

If you assume a bike with a sloped top tube you can have a constant
Stack measurement with a large difference in the actual distance from
the seat to the pedals.

Slope or otherwise of top tube doesn't matter.

So, if it is possible to have a range of how the bike actually fits
with a constant Stack and Reach dimension then what information does
the Reach and Stack provide?

The relative position of your feet and hands.

Nope. A bike with the exact same Stack and Reach measurements can have
substantially different distances from the seat to the handle bars and
from the seat to the bottom bracket.

Um, this is a pretty bad reading of what I wrote. I said reach and stack
provide the relative position of feet and hands and you say "Nope" then
start talking about relative position of bum/seat to those?

Rephrase your answer to "Yep" and I'll accept it.

Combine with a seat-tube
angle and your leg length, and you've got the lot. Angles are similar
for similar types of bikes, your leg length is going to be fixed, so
actually assuming you're buying a "road bike" or a "tt bike", you're
going to know the lot with just reach and stack.

Yes, I did point out that there was a substantial difference between
the usual road bike and a Tri or Time Trial bike. But as I also
pointed out there is no indication of the distance from the seat to
the handle bars using only the Stack and Reach dimensions as they are
measured from the BB, where you feet are, not the seat where your butt
is.

But if you know the angle of the seat tube, which for a road and TT bike
are going to be predictable, you get the rest of the information - your
leg length is the other variable.

Obviously if you're doing less-mainstream bikes, you need more detail,
but for buying a fairly normal racing bike, you don't.

Or you could try this explanation :

http://www.cervelo.com/en/engineerin...y-and-fit.html


Yup. I read it and it appears that you need the Stack and Reach
dimensions and then you need the chart to refer to...

But just go down to your friendly Local Bike Shop and measure some
framed. Reach is the measurement from a vertical line through the BB
to the top of the head tube. Stack is the measurement from a
horizontal line through the BB to the top of the head tube.

Find a normal road bike and measure the Stack and Reach. Then have a
look at a top of the line Tri or Time Trial bike and you may find that
the Stack and Reach are essentially the same as the road bike.

Have you done this? I think not...

Look at the Cervelo bikes - here's the specs of their R3 (road) and P3
(TT) bikes

http://www.cervelo.com/media/docs/R3...7652f024-0.pdf

http://www.cervelo.com/media/docs/P3...ceb5e22f-1.PDF

The reach and stack on the TT bike is not similar to the road bike. They
are different. I'm afraid your hypothesis is false.

Note also that Cervelo don't just specify reach/stack - see the PDFs.

Then sit on them and you will discover that while the Stack and Reach
are the same on both bikes your position on one bike will be much,
much different then on the other.


No what I wrote is correct.

If you were to use the Stack and Reach measurements to select a bike
you would have very different sizes.

The P3 (size 54) has a Reach of 411, the R3 (size 54) has a reach of
378. Or, a P3 with a 378 Reach (375 actually) is a size 45

Which is what I've been saying, that the Stack - Reach measurements
are essentially a meaningless measurement.

You'd need to know the stack/reach combo which is good for you on a road
bike, and the equivalent on a TT bike, but once you've done that you're
sorted.

Obviously. Just as I would need to know the top tube length for a road
and TT bike, which I can measure with a tape measure.

So what is this Reach and Stack measurement - which is difficult to
measure - telling me that the traditional measurements don't?

Or to put it another way. What good are they?
--
cheers,

John B.

I alsways thought that REACH was the distance one had to reach in order to grip the handlebar. Thus headtube angle, seattube angle, stem length and seatpost setback all affected the REACH. Now it seems as if REACH is smoething entirely different that only complicates things.

Cheers

They have invented a new measurement. the "New" Reach is the
horizontal distance from a vertical line through the bottom bracket to
the head tube. They have also invented a "Stack" measurement that is a
vertical measurement from a horizontal line through the bottom bracket
to the top of the head tube.
--
cheers,

John B.

Thanks. Was just looking at an article about it and saw that the Stack is affected by whether the headset is integrated, hidden etcetera.

http://velonews.competitor.com/2011/...ndustry_154565

"The biggest drawback of current stack and reach frame sizing is that the effective head tube height varies due to headset type. If the frame has an integrated headset, it will have effectively about 2cm less stack than a frame with the same stack measurement with a standard headset. This is why I think that stack (and reach) would be measured to the headset upper bearing cover, rather than to the top of the head tube. As long as we're resolved to go to the stack and reach system, why don't we make this change, too? That way, we can start with a new, clean frame measurement system without a fudge factor in it.
Read more at http://velonews.competitor.com/2011/01/bikes-and-tech/technical-faq/technical-faq-with-lennard-zinn-lz-suggest-some-new-years-resolutions-for-the-bike-industry_154565#0zCkJQRiAaJ45zPY.99"

Funny how advances in bicycling make everything much more complicated.

This new Reach doesn't seem to take into consideration the distance behind the bottom bracket to the saddle.

Cheers

On 12/23/2015 5:57 AM, John B. wrote:

They have invented a new measurement. the "New" Reach is the
horizontal distance from a vertical line through the bottom bracket to
the head tube. They have also invented a "Stack" measurement that is a
vertical measurement from a horizontal line through the bottom bracket
to the top of the head tube.

Remember back when the only confusion was "center to center" vs. "center
to top"? Things are so much more creative now!

Should we have a "dimension inventing" contest?


--
- Frank Krygowski

On Wednesday, December 23, 2015 at 7:03:33 AM UTC-8, Frank Krygowski wrote:
On 12/23/2015 5:57 AM, John B. wrote:

They have invented a new measurement. the "New" Reach is the
horizontal distance from a vertical line through the bottom bracket to
the head tube. They have also invented a "Stack" measurement that is a
vertical measurement from a horizontal line through the bottom bracket
to the top of the head tube.

Remember back when the only confusion was "center to center" vs. "center
to top"? Things are so much more creative now!

Should we have a "dimension inventing" contest?


It is a vast improvement over the bad-old-days -- particularly TT, stack, BB drop and stand-over. Reach does give you some basic coordinates (not getting into that argument), and other popular dimensions do allow you to compare an existing beloved frame to a new one. Back in the day, there often was little provided in the way of measurement -- http://bhovey.com/Masi/MasiCatalogs/...mpLG/masi4.htm

Gads, all of their frames came with 73.3 parallel HT/ST angles -- from 50cm to 62cm? Yikes. I rode a 64cm frame back then, and a lot of the Italian frames were just scaled-up small frames, and they ended up with short top-tubes (which was sort of a thing back then anyway). Apart from just the measurement issues, the frames themselves were not as creatively shaped as modern frames which vary much more by size -- and even use different tube sets or lay-ups in different sizes.

Back in the day, some makers were better than others -- Trek, for example, really did it up when they started making frames. IIRC, their catalogs provided a wide variety of dimensions. Others not so much.

-- Jay Beattie.

On Wednesday, December 23, 2015 at 7:03:33 AM UTC-8, Frank Krygowski wrote:
On 12/23/2015 5:57 AM, John B. wrote:

They have invented a new measurement. the "New" Reach is the
horizontal distance from a vertical line through the bottom bracket to
the head tube. They have also invented a "Stack" measurement that is a
vertical measurement from a horizontal line through the bottom bracket
to the top of the head tube.

Remember back when the only confusion was "center to center" vs. "center
to top"?

Back when we were even _more_ stupid! Leading to finding yourself hearing, in the bike shops: "Bikes are measured by the seat tube but what you should really buy a bike for is the top tube".

Things are so much more creative now!

Yeah! We have now progressed to using TWO variables! 'Nuther 20 or 30 years from now...

On Wednesday, December 23, 2015 at 3:37:08 PM UTC, jbeattie wrote:

It is a vast improvement over the bad-old-days -- particularly TT, stack, BB drop and stand-over. Reach does give you some basic coordinates (not getting into that argument), and other popular dimensions do allow you to compare an existing beloved frame to a new one. Back in the day, there often was little provided in the way of measurement -- http://bhovey.com/Masi/MasiCatalogs/...mpLG/masi4.htm

Gads, all of their frames came with 73.3 parallel HT/ST angles -- from 50cm to 62cm? Yikes. I rode a 64cm frame back then, and a lot of the Italian frames were just scaled-up small frames, and they ended up with short top-tubes (which was sort of a thing back then anyway). Apart from just the measurement issues, the frames themselves were not as creatively shaped as modern frames which vary much more by size -- and even use different tube sets or lay-ups in different sizes.

Back in the day, some makers were better than others -- Trek, for example, really did it up when they started making frames. IIRC, their catalogs provided a wide variety of dimensions. Others not so much.

-- Jay Beattie.

Lotta people thing you're wrong. For instance, I remember Chalo slating the popular Gunnar bikes for not being proportional to size in the rear triangle, right here on this board.

There are designers who're keen on a proper fit of cyclist to bike, who do go the extra length. Andy Blance of Thorn, the renowned British touring bike maker also favoured by Sheldon Brown, for instance, offers two top tube lengths per "size" depending on whether you want to use straight bars or drop bars. His bikes have a famously good fit if you take all the measurements required and give the necessary thought to how you want to use the bike, all of which is on his fitting form at http://www.sjscycles.com/thornpdf/SetUpHiRes.pdf or in a different version in the Thorn mega brochure on p20 in his brochu http://www.sjscycles.com/thornpdf/TH...A_BROCHURE.pdf

Andre Jute
Logic rules