Teach an old guy about "new frame sizing"

Bob said:

OK... I'm a 70's guy. Back then we bought a frame on the large side
and minimized seat post and stem extension - not that there were many
options since they were not very long. Recently the trend definitely
seems to be toward smaller frames with more seat post and stem
extension and/or stems and bars with lots of rise ? But, for any given
fitting desired (i.i. seat surface to pedal surface, seat position to
stem/bar location) I think we can use either approach to "fit" a bike
(I think; comments welcome).

So, what's the advantage in a smaller frame and more extension of the
other components? I would think that in general, a larger frame with
smaller extensions will be stiffer and more desirable.

Enlightening appreciated,

Two things come to my mind 1. A smaller frame is lighter, stiffer and
able to turn faster etc, and 2. It is easier for a manufacturer to make
one small frame, which can be adapted to small and large individuals
than to manufacture several frame sizes.
HTH
EJ in NJ

Quoted message said:

2. It is easier for a manufacturer to make
one small frame, which can be adapted to small and large individuals
than to manufacture several frame sizes.
HTH
EJ in NJ

Or, the dealer could stock his store with nothing but 25" frames and
accommodate the average and smaller rider by punching that saddle right
down against the top tube. This seemed to be the method used for most
Schwinns I saw as a kid.

Ernie Willson said:

Bob said:

So, what's the advantage in a smaller frame and more extension of the
other components?

Two things come to my mind 1. A smaller frame is lighter,

But you just compensate with a longer seatpost. Is there an actual
weight savings?

Quoted message said:

stiffer

A larger frame is more flexible? Where does it flex more? Why?

Quoted message said:

and
able to turn faster

How is that? Actually, when I went from a slightly too-small frame to
one that fit me very well, I could corner much better, because my center
of gravity was in a better place and I was more stable. I was racing
criteriums at the time, and there was a marked difference. The only way
a smaller frame could corner faster, simply because it has a shorter
wheelbase, is if you are holding the rear wheel in place and turning
around your hand.

Quoted message said:

...and 2. It is easier for a manufacturer to make
one small frame, which can be adapted to small and large individuals
than to manufacture several frame sizes.

I agree with this.

On Wed, 22 Mar 2006 23:19:35 GMT, "Jay S. Hill" <[email hidden]>

Quoted message said:

A larger frame is more flexible? Where does it flex more? Why?

Because the tubes are longer.

JT

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Jay S. Hill said:

Ernie Willson said:

Bob said:

So, what's the advantage in a smaller frame and more extension of
the other components?

Two things come to my mind 1. A smaller frame is lighter,

But you just compensate with a longer seatpost. Is there an actual
weight savings?

2003 Giant TCR Composite, size L: 1068g
2003 Giant TCR Composite, size S: 972.5g

L: 55.5cm seat tube
S: 44cm seat tube

L: 196g Thomson Elite 25cm seatpost
S: 224g Thomson Elite 33cm seatpost

L: max seat height (from BB) = 72.5cm
S: max seat height (from BB) = 69cm

L: frame + seatpost = 1264g
S: frame + seatpost = 1197g

So that's a savings of 67.5g for almost the same saddle height, a value that
pretty much falls into the noise after compensating for the lengthening of
the headtube/downtube/top tube/seatstays in size large.
--
Phil, Squid-in-Training

Jay S. Hill said:

Actually, when I went from a slightly too-small frame to
one that fit me very well, I could corner much better, because my center
of gravity was in a better place and I was more stable. I was racing
criteriums at the time, and there was a marked difference.

You center of gravity will move *very* slightly upward and rearward
with a larger frame... and I don't see either of these being beneficial
to handling. For even weight distribution on the wheels, a smaller
frame is better... you'll still have more weight on the rear, anyway.

Bob said:

So, what's the advantage in a smaller frame and more extension of the
other components?

My new city bike has a slightly compact frame with extended seat tube,
so the seatpost isn't much more exposed than a traditional frame. The
nice benefit of this is being able to get a proper bar height w/o too
many spacers on today's threadless headsets, and it gives a couple
cms's more standover for waiting at stoplights.

My other ride is traditional frame with a "fist's" worth or so of post
showing and I like it just as much to be honest, it looks nicer imho. I
like the look of the quill stem as well.

Quoted message said:

I would think that in general, a larger frame with
smaller extensions will be stiffer and more desirable.

Smaller frames are stiffer, but as to which is more desirable, it
depends. For a touring and long distance bike, gimme a big ass frame
that's got a better ride, I can live with flex. For a city ride where I
do lots of stoplight sprints, a modern compact with uber stiff
threadless front end is appreciably different.

John Forrest Tomlinson said:

On Wed, 22 Mar 2006 23:19:35 GMT, "Jay S. Hill" <[email hidden]>

Quoted message said:

A larger frame is more flexible? Where does it flex more? Why?

Because the tubes are longer.

True enough, but since the OP has to use a longer stem and seat post,
he gets more flex there. And let's face it, frame flex is usually
minor compared to riding with a too-long stem.

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

Bob said:

So, what's the advantage in a smaller frame and more extension of the
other components? I would think that in general, a larger frame with
smaller extensions will be stiffer and more desirable.

It's a bit more complicated than that.

For every frame, there's an "ideal" stem length. If you have to
exceed this, handling suffers. If you need a considerably shorter
stem to get the proper fit, the handling won't suffer as much, but it
won't be perfect either.

Standover clearance is nice - many ride without any, but all other
things being equal, it's always good to have some.

The real difference in "fit" between frames of different sizes is in
the head tube length. This will determine the vertical adjustment
range of the bars. A taller frame will have a handlebar height range
that's higher than a smaller frame.

There are those who'll claim weight savings on a small frame, but
you're going to offset that with a longer stem and potentially longer
seat post (which will also give you back the flex you avoid in the the
smaller frame - not that it's usually important).

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

On Wed, 22 Mar 2006 19:21:58 -0700, Mark Hickey <[email hidden]>

Quoted message said:

John Forrest Tomlinson said:

On Wed, 22 Mar 2006 23:19:35 GMT, "Jay S. Hill" <[email hidden]>

Quoted message said:

A larger frame is more flexible? Where does it flex more? Why?

Because the tubes are longer.

True enough, but since the OP has to use a longer stem and seat post,
he gets more flex there. And let's face it, frame flex is usually
minor compared to riding with a too-long stem.

Flex in the seat post is a good thing. Flex in the stem, sort of good
(for comfort), sort of bad (for handling and accelleration). Flex in
the frame, bad (for control and power transmission).

JT

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

Quoted message said:

John Forrest Tomlinson said:

On Wed, 22 Mar 2006 23:19:35 GMT, "Jay S. Hill" <[email hidden]>

Quoted message said:

A larger frame is more flexible? Where does it flex more? Why?

Because the tubes are longer.

True enough, but since the OP has to use a longer stem and seat post,
he gets more flex there. And let's face it, frame flex is usually
minor compared to riding with a too-long stem.

Longer stem? Have makers begun to use lengthwise-shorter frames?

--
Phil, Squid-in-Training

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

Quoted message said:

OK... I'm a 70's guy. Back then we bought a frame on the large side
and minimized seat post and stem extension - not that there were many
options since they were not very long. Recently the trend definitely
seems to be toward smaller frames with more seat post and stem
extension and/or stems and bars with lots of rise ? But, for any given
fitting desired (i.i. seat surface to pedal surface, seat position to
stem/bar location) I think we can use either approach to "fit" a bike
(I think; comments welcome).

So, what's the advantage in a smaller frame and more extension of the
other components? I would think that in general, a larger frame with
smaller extensions will be stiffer and more desirable.

In turns I find that my XS (42cm actual) frame doesn't have a tube where my
knees are, so I find myself feeling a bit squirrelly in turns. My old frame
was a GT with the triple triangle setup, which I often butted my legs up
against to help steer the bike.
--
Phil, Squid-in-Training

Phil said:

My old frame
was a GT with the triple triangle setup, which I often butted my legs up
against to help steer the bike.

Interesting. I've never touched the frame with a leg while cornering
before. I'll have to experiment with that. So you just clamped the
frame between your legs, or leaned just one against it?

Have you ever tried riding with both hands holding the top tube? It's
really weird, but once you get the hang of it, there's a lot less
steering noise in your line. It's nothing I'd want to do for any length
of time for safety reasons, but it can communicate a lot about how
bikes balance and turn. Fun exercise.

-Mike

"Phil, Squid-in-Training" <[email hidden]>

Quoted message said:

"Mark Hickey" <[email hidden]> wrote

Quoted message said:

John Forrest Tomlinson said:

"Jay S. Hill" <[email hidden]> wrote:

>A larger frame is more flexible? Where does it flex more? Why?

Because the tubes are longer.

True enough, but since the OP has to use a longer stem and seat post,
he gets more flex there. And let's face it, frame flex is usually
minor compared to riding with a too-long stem.

Longer stem? Have makers begun to use lengthwise-shorter frames?

Not that I'm aware of. My comments were about the contention that
riding a smaller frame with longer stem and seat post would reduce
flex, not any trend in the industry.

At least my frames aren't getting shorter. ;-)

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

On 23 Mar 2006 05:23:06 -0800, "Mike Reed" <[email hidden]>

Quoted message said:

Phil said:

My old frame
was a GT with the triple triangle setup, which I often butted my legs up
against to help steer the bike.

Interesting. I've never touched the frame with a leg while cornering
before. I'll have to experiment with that. So you just clamped the
frame between your legs, or leaned just one against it?

Have you ever tried riding with both hands holding the top tube? It's
really weird, but once you get the hang of it, there's a lot less
steering noise in your line. It's nothing I'd want to do for any length
of time for safety reasons, but it can communicate a lot about how
bikes balance and turn.

There was a drill I used to teach people more about how they control
the bike that that involved them riding through an easy slalom course
first with no hands. THen with hands on the bars but out of the
saddle, and lastly with their butt on the saddle and hands on the bars
without feet on the pedals. We steer with all those contact patches.

I don't think it's wise to regularly steer with your knees or legs on
the top tube, though I've seen people use their legs to kill a shimmy
that comes on suddenly. Perhaps also to steer the bike in some
radical emergency.

JT

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Bob said:

OK... I'm a 70's guy. Back then we bought a frame on the large side
and minimized seat post and stem extension - not that there were many
options since they were not very long. Recently the trend definitely
seems to be toward smaller frames with more seat post and stem
extension and/or stems and bars with lots of rise ? But, for any given
fitting desired (i.i. seat surface to pedal surface, seat position to
stem/bar location) I think we can use either approach to "fit" a bike
(I think; comments welcome).

So, what's the advantage in a smaller frame and more extension of the
other components? I would think that in general, a larger frame with
smaller extensions will be stiffer and more desirable.

Enlightening appreciated,

Get the frame that fits, not bigger or smaller. get the frame with the
proper seat tube angle for you femur and then the proper top tube
length for your torso, arms and flexibility.

Few sizes(s, m, l, xl,) type frames are for the manufacturer to save
money, the so called 'compacts' and do nothing 'better'.

Go to a bike shop that actually does bike fits, on a fit cycle and have
them do a fit on you. No such thing as a test ride around the parking
lot fit...they are just trying to sell ya something

Ideally, a bike shop tnat starts with frames, and then builds the bike
you want.

Mike Reed said:

Phil said:

My old frame
was a GT with the triple triangle setup, which I often butted my
legs up against to help steer the bike.

Interesting. I've never touched the frame with a leg while cornering
before. I'll have to experiment with that. So you just clamped the
frame between your legs, or leaned just one against it?

I often instinctively clamp the TCR top tube with my knees when I drink from
the bottle and on the real fast race-pace rides in the corners. While
drinking, with one hand on the bars, the knee on the top tube acts like a
second hand on the handlebars.

The GT's triple triangle setup was really wide, so the pseudo-seatstays were
really close to my knees anyway.

Quoted message said:

Have you ever tried riding with both hands holding the top tube? It's
really weird, but once you get the hang of it, there's a lot less
steering noise in your line. It's nothing I'd want to do for any
length of time for safety reasons, but it can communicate a lot about
how bikes balance and turn. Fun exercise.

I have a couple of times...

--
Phil, Squid-in-Training

Quoting John Forrest Tomlinson <[email hidden]>:

Quoted message said:

Flex in the seat post is a good thing. Flex in the stem, sort of good
(for comfort), sort of bad (for handling and accelleration). Flex in
the frame, bad (for control and power transmission).

Out of interest, how can your legs tell the difference between the
seatpost flexing, which is apparently good, and the seat tube flexing,
which is apparently bad?
--
David Damerell <[email hidden]> Kill the tomato!
Today is Second Brieday, March.

Phil said:

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

Quoted message said:

OK... I'm a 70's guy. Back then we bought a frame on the large side
and minimized seat post and stem extension - not that there were many
options since they were not very long. Recently the trend definitely
seems to be toward smaller frames with more seat post and stem
extension and/or stems and bars with lots of rise ? But, for any given
fitting desired (i.i. seat surface to pedal surface, seat position to
stem/bar location) I think we can use either approach to "fit" a bike
(I think; comments welcome).

So, what's the advantage in a smaller frame and more extension of the
other components? I would think that in general, a larger frame with
smaller extensions will be stiffer and more desirable.

In turns I find that my XS (42cm actual) frame doesn't have a tube where my
knees are, so I find myself feeling a bit squirrelly in turns. My old frame
was a GT with the triple triangle setup, which I often butted my legs up
against to help steer the bike.

I always feel weird at first when I switch to my MTB and my knees clonk
together when I go to grip the TT with them. I like the feel of the
higher TT, but I'm not sure that it really affects my handling.