Teach an old guy about "new frame sizing"

Bob wrote:
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

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 wrote:
Bob wrote:

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?

stiffer

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

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.

...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"
wrote:

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 wrote:
Ernie Willson wrote:
Bob wrote:

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 wrote:
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.

John Forrest Tomlinson wrote:

On Wed, 22 Mar 2006 23:19:35 GMT, "Jay S. Hill"
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.

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
wrote:

John Forrest Tomlinson wrote:

On Wed, 22 Mar 2006 23:19:35 GMT, "Jay S. Hill"
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.

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" wrote in message
...
John Forrest Tomlinson wrote:

On Wed, 22 Mar 2006 23:19:35 GMT, "Jay S. Hill"
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?

--
Phil, Squid-in-Training

"Phil, Squid-in-Training"
wrote:

"Mark Hickey" wrote
John Forrest Tomlinson wrote:
"Jay S. Hill" 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