The difference tube diameter makes

On Wednesday, August 13, 2014 11:30:31 AM UTC-4, Frank Krygowski wrote:
On 8/13/2014 7:04 AM, Rolf Mantel wrote:

Am 13.08.2014 12:54, schrieb John B. Slocomb:



One wonders why skinny tube racing bikes were used for so long a

period. It is certainly not because engineers didn't know that a thin

large diameter tube is stiffer then a thin small diameter tube.



I think there's always been a tremendous amount of bike "engineering"

that was really tradition. And come to think of it, that's true of

other fields as well. Look at the 100 year history of auto design, for

example.



the most important aspect has always been minimal weight. For a given

minimal thickness of tubing, a small diameter tube is lighter than a

large diameter tube.



Large diameter tubes only started coming up when technology reached the

stage that the minimum thickness of tube that could be produced and

welded became significantly thinner than the minimum thickness necessary

for structural stability (I believe this was reached for aluminium

frames in the 1980s and for steel frames a lot later).



IIRC, the first I heard of a significant design choice based on

oversized tubes was in an article about Gary Klein. Supposedly, he was

an MIT engineering student who was excited to visit an exhibit of a

super-light bicycle; but was very disappointed to see that it had no

engineering innovation. They'd simply drilled and whittled conventional

parts down to stupid-light thicknesses.



He then started thinking about using aluminum frames, and it occurred to

him that aluminum's lower density would allow thicker (non-denting) tube

walls at larger diameters. So we got light & rigid Klein frames.

Cannondale and others copied the concept.



Tandem tubing has long been oversized. Our 1979 tandem is oversized

Reynolds 531. But the wall thickness is no less than standard, probably

to allow brazing by any guy with a torch. So back in those days, the

extra stiffness from oversized steel tubes came with a weight penalty.



Since then, there have been improvements in steel alloys and welding

techniques, so oversized steel works better than it once did.





--

- Frank Krygowski

I think that a lot of bicycle design "tradition" was and is because of


uci and other regulations.




i can only imagine what would happen to diamond frame bicycles if recumbent or even semi-recumbent bicycles were allowed in mainstream races. I'm sure we'd soon see some really interesting bicycle designs and advances.

Cheers

On Wednesday, August 13, 2014 4:19:36 AM UTC+1, James wrote:

If you use muscle to bend a

spring and let it return by reducing the effort back to zero, a perfect

spring will return the energy put into it, but the returned energy

doesn't end up as calories in your muscles again. Instead your body

consumes energy as you bend and release the spring. I think similarly

when you flex a bicycle frame, the energy that went into flexing it

doesn't find it's way to increasing your kinetic energy forward on the

bike (some might, but certainly not all). More likely it is wasted

while your body deals with it.

The only good thing that comes from spring in a bike frame is suspension

- but then slightly fatter tyres and less air pressure can achieve the

same effect on bitumen - better in fact, because it doesn't bounce the

whole think around. It's only when the bumps get really big that we

need to resort to shock absorbers, etc.

Depends how fat your tyres are and how competently the tubes in you bike have been scaled and in which material.

I've deliberately left mechanical and hydraulic suspension behind on my bicycle. But, because I've replaced them with huge low pressure balloons, higher requirement are in fact put on the frame.

After five years of experience with fat tyres as the only suspension on my bike (besides a Brooks saddle which should also be counted as a suspension item) I have concluded that:

1. Steel has a superior comfort perception apparently impossible to achieve in aluminum no matter how you scale up the ali tubes from a successful steel execution. An ali bike that by analysis and test resists the same headtube to frame-end (rear dropout) torque as one in steel just feels harsher than steel. In my opinion an ali bike in the Dutch town bike styles I prefer really needs a suspension fork and a suspended saddle, at a minimum, or very fat tyres.

2. Any old fool can make an exceedingly stiff steel bike out of plumbing pipes; any old fool only interested in low weight can make too-thin steel tubes into a wet noodle. The art of building a steel bicycle which is at the same time resists and revolves all forces on it correctly lies in scaling the tubes right. A racing frame, no matter how light, with a bottom bracket that waves in the wind with each pedal stroke is a failure. A city bike that transfers reptilian ripples to your hands over chip'n'seal surfaces is a failure. A successful steel frame is sweetly forgiving of a wide range of road conditions, without ever attempting to make a steering input. Sweetly forgiving, and NO steering input, those are the key phrases. No matter that the dumber engineers sneer at this idea as "stiff yet flexible", and that some of the dumber writers on bicycles actually fall into the false dichotomy trap of using such silly phrases, this a real, perceptible parameter, Perhaps we should call it "stiff, yet lithe". It is because of this perception of the designer's degree of competence (or luck) quite as much as a proper fit that many people conclude that "steel bikes are more comportable than ali bikes". I'm one of them. I have half a century of experience with turning informed and experienced subjective judgement into money and I'm exceedingly comfortable with that conclusion.

3. The finest suspension medium in the world is air, and it is already on every bike, including the cheapest. (Well, we can leave the tubular guys to their masochistic miseries.) If you add more air volume but at a lower pressure, you add more suspension to the bike. Of course it depends where you start how soon the benefit may be felt and at what magnitude. On a road bike a number that you keep hearing in surprised tones from roadies of much and wide experience is 32mm. In my sort of fast city/loaded touring bike, 47mm is almost universally accepted as the minimum, and automatically taken as the maximum by lazy designers (not necessarily ignorant or incompetent, just unable to shrug off the overbearing influence of racing design). But north of 47mm is where real comfort starts and accelerates (heh-heh in both senses of the word) like a hoon. The fatter the tyre and the lower the pressure per unit of volume, the greater the comfort. If the tyre is in addition slick, the rolling resistance is so much less than on a narrow, treaded tyre as to start making an efficiency difference. You'd think these huge tyres, especially if they're banded against punctures, would slow you by their very weight, but they don't, because they are so secure that you pay the road surface no never mind: downhill on the bad roads locally I sit at the bottom and wait for the roadies, and wonder why vthey develop white stress lines around their mouths from trying to keep up with me.

4. There are some complications of really fat tyres that make the parameters I've described above not just desirable but essential. If you fit really fat tyres, and let your riders take advantage of the speed, comfort and security they offer, you'd better give them a really stiff chassis to resist the higher demands they will inevitably put on it. And, to prevent that stiff chassis feeling harsh, it had better be in steel and very well scaled indeed, which could be expensive in custom tube drawing and empirical testing. More, if the bike is to be capable of carrying significant payload beside the rider, which means panniers imparting perpendicular forces, it had better be stiff in three dimensions, not just the flat diamond-trianngle conjunction that will do for road bikes.

4. While I have as little patience as Jobst Brandt with the idea that a flexible, springy frame is somehow an advantage (see above about NO STEERING INPUTS), I'm big on the greater absorption (for want of a better word) of the smallest micro ripples by steel, which in turn leads to long-term comfort, and the absorption of the larger road irregularities of huge low-pressure tyres fitted to a correctly scaled stiff steel frame, which in turn leads to security. Comfort and security together make for surprising speed.

Andre Jute
And I look good in purple shorts!

On Wednesday, August 13, 2014 5:51:00 PM UTC+1, Sir Ridesalot wrote:

I think that a lot of bicycle design "tradition" was and is because of

uci and other regulations.

The UCI actually said, at some point in their shameful persecution of Obree, that their idea of a bicycle was fixed at a point in time.

i can only imagine what would happen to diamond frame bicycles if recumbent or even semi-recumbent bicycles were allowed in mainstream races. I'm sure we'd soon see some really interesting bicycle designs and advances.

I can see the UCI's point, to a certain extent. If they let, say, recumbents, into the TdF, it becomes a race of technology, not human athletes.

The Obree case was different: the UCI's entry point against Obree was not the bike, but his stance on it. That struck many as a bit personal. I think that if a cyclist wants to set a record sitting backwards on his bike, he should get the record as long as the bike fits formula.

Andre Jute

On 8/13/2014 12:51 PM, Sir Ridesalot wrote:


I think that a lot of bicycle design "tradition" was and is because of


uci and other regulations.




i can only imagine what would happen to diamond frame bicycles if recumbent or even semi-recumbent bicycles were allowed in mainstream races. I'm sure we'd soon see some really interesting bicycle designs and advances.

The UCI regulations don't bother me much. I think it's analogous to,
say, the regulations on golf equipment. They have rules regarding how
lively the club head can be (the coefficient of restitution), shape of
grooves, etc. Someone has to decide what the rules are for a sport, and
there's some logic to restricting expensive technology escalation and
keeping things reasonably equal between athletes.

Bicycling is unusual in that it's a sport, but it's much more often
something else - non-competitive leisure activity, practical
transportation, kid's fun, etc. As cool as I think recumbents can be, I
don't think they really have many advantages for most users. Sure, they
can be faster especially once they're streamlined, but they then lose a
lot of the standard bicycle's amazing versatility.


--
- Frank Krygowski

On Wednesday, August 13, 2014 8:30:31 AM UTC-7, Frank Krygowski wrote:
On 8/13/2014 7:04 AM, Rolf Mantel wrote:

Am 13.08.2014 12:54, schrieb John B. Slocomb:



One wonders why skinny tube racing bikes were used for so long a

period. It is certainly not because engineers didn't know that a thin

large diameter tube is stiffer then a thin small diameter tube.



I think there's always been a tremendous amount of bike "engineering"

that was really tradition. And come to think of it, that's true of

other fields as well. Look at the 100 year history of auto design, for

example.



the most important aspect has always been minimal weight. For a given

minimal thickness of tubing, a small diameter tube is lighter than a

large diameter tube.



Large diameter tubes only started coming up when technology reached the

stage that the minimum thickness of tube that could be produced and

welded became significantly thinner than the minimum thickness necessary

for structural stability (I believe this was reached for aluminium

frames in the 1980s and for steel frames a lot later).



IIRC, the first I heard of a significant design choice based on

oversized tubes was in an article about Gary Klein. Supposedly, he was

an MIT engineering student who was excited to visit an exhibit of a

super-light bicycle; but was very disappointed to see that it had no

engineering innovation. They'd simply drilled and whittled conventional

parts down to stupid-light thicknesses.



He then started thinking about using aluminum frames, and it occurred to

him that aluminum's lower density would allow thicker (non-denting) tube

walls at larger diameters. So we got light & rigid Klein frames.

Cannondale and others copied the concept.

Klein copied the concept, and thus his mostly loosing patent infringement suit against Cannondale. Harriet Fell, Sheldon Brown's wife, built a large diameter aluminum frame bike before Klein, so did Bill Shook (American Classic). It's all on the interweb.

Klein reinforced his stays with boron, so that was unique. I rode on a Klein sponsored team back when he was working out of shed in San Martin. Those early frames were really stiff compared to steel, but they looked weird (IMO)and were super expensive. I couldn't afford one and still liked the steel aesthetic. Plus, even as a big rider, I could get a plenty stiff frame using SP, but it was just a boat anchor by today's standards. I only made the switch to OS aluminum after breaking my fourth or fifth steel frame and right when Cannondale starting making a lower cost option to the Klein. I never looked back.

BTW, there was some frame engineering back then. The Exxon Graftek in 1975.. Speedwell and other Ti builders. Both of those were noodley if not plain dangerous. Otherwise, it was just Italian versus English, and your choice of butting patterns and wall thickness (SP/SL/SLX, TSX (later)and all the 531 variants) Real changes came later with shaping and new steel alloys that air hardened, etc. -- and I think may of those came about because OS aluminum was eating in to the steel market.

Now everyone is chasing CF, which, like early aluminum, is claimed to be too stiff, too soft, too light, too dangerous, etc., etc. Everyone gets entrenched in their technology and claims the latest thing is bad -- and sometimes it is. I figure that CF is not too bad, and it seems to be maturing as a technology. My CF frame beats the hell out of any steel frame I ever owned in terms of weight versus stiffness, which matters when you're riding a 63cm frame (Cannondale conventional DF geometry).

-- Jay Beattie.

On 8/13/2014 1:19 PM, Andre Jute wrote:
On Wednesday, August 13, 2014 4:19:36 AM UTC+1, James wrote:

If you use muscle to bend a

spring and let it return by reducing the effort back to zero, a perfect

spring will return the energy put into it, but the returned energy

doesn't end up as calories in your muscles again. Instead your body

consumes energy as you bend and release the spring. I think similarly

when you flex a bicycle frame, the energy that went into flexing it

doesn't find it's way to increasing your kinetic energy forward on the

bike (some might, but certainly not all). More likely it is wasted

while your body deals with it.

The only good thing that comes from spring in a bike frame is suspension

- but then slightly fatter tyres and less air pressure can achieve the

same effect on bitumen - better in fact, because it doesn't bounce the

whole think around. It's only when the bumps get really big that we

need to resort to shock absorbers, etc.

Depends how fat your tyres are and how competently the tubes in you bike have been scaled and in which material.

I've deliberately left mechanical and hydraulic suspension behind on my bicycle. But, because I've replaced them with huge low pressure balloons, higher requirement are in fact put on the frame.

After five years of experience with fat tyres as the only suspension on my bike (besides a Brooks saddle which should also be counted as a suspension item) I have concluded that:

1. Steel has a superior comfort perception apparently impossible to achieve in aluminum no matter how you scale up the ali tubes from a successful steel execution. An ali bike that by analysis and test resists the same headtube to frame-end (rear dropout) torque as one in steel just feels harsher than steel. In my opinion an ali bike in the Dutch town bike styles I prefer really needs a suspension fork and a suspended saddle, at a minimum, or very fat tyres.

2. Any old fool can make an exceedingly stiff steel bike out of plumbing pipes; any old fool only interested in low weight can make too-thin steel tubes into a wet noodle. The art of building a steel bicycle which is at the same time resists and revolves all forces on it correctly lies in scaling the tubes right. A racing frame, no matter how light, with a bottom bracket that waves in the wind with each pedal stroke is a failure. A city bike that transfers reptilian ripples to your hands over chip'n'seal surfaces is a failure. A successful steel frame is sweetly forgiving of a wide range of road conditions, without ever attempting to make a steering input. Sweetly forgiving, and NO steering input, those are the key phrases. No matter that the dumber engineers sneer at this idea as "stiff yet flexible", and that some of the dumber writers on bicycles actually fall into the false dichotomy trap of using such silly phrases, this a real, perceptible parameter, Perhaps we should call i
t "stiff, yet lithe". It is because of this perception of the designer's degree of competence (or luck) quite as much as a proper fit that many people conclude that "steel bikes are more comportable than ali bikes". I'm one of them. I have half a century of experience with turning informed and experienced subjective judgement into money and I'm exceedingly comfortable with that conclusion.

3. The finest suspension medium in the world is air, and it is already on every bike, including the cheapest. (Well, we can leave the tubular guys to their masochistic miseries.) If you add more air volume but at a lower pressure, you add more suspension to the bike. Of course it depends where you start how soon the benefit may be felt and at what magnitude. On a road bike a number that you keep hearing in surprised tones from roadies of much and wide experience is 32mm. In my sort of fast city/loaded touring bike, 47mm is almost universally accepted as the minimum, and automatically taken as the maximum by lazy designers (not necessarily ignorant or incompetent, just unable to shrug off the overbearing influence of racing design). But north of 47mm is where real comfort starts and accelerates (heh-heh in both senses of the word) like a hoon. The fatter the tyre and the lower the pressure per unit of volume, the greater the comfort. If the tyre is in addition slick, the rolling re
sistance is so much less than on a narrow, treaded tyre as to start making an efficiency difference. You'd think these huge tyres, especially if they're banded against punctures, would slow you by their very weight, but they don't, because they are so secure that you pay the road surface no never mind: downhill on the bad roads locally I sit at the bottom and wait for the roadies, and wonder why vthey develop white stress lines around their mouths from trying to keep up with me.

4. There are some complications of really fat tyres that make the parameters I've described above not just desirable but essential. If you fit really fat tyres, and let your riders take advantage of the speed, comfort and security they offer, you'd better give them a really stiff chassis to resist the higher demands they will inevitably put on it. And, to prevent that stiff chassis feeling harsh, it had better be in steel and very well scaled indeed, which could be expensive in custom tube drawing and empirical testing. More, if the bike is to be capable of carrying significant payload beside the rider, which means panniers imparting perpendicular forces, it had better be stiff in three dimensions, not just the flat diamond-trianngle conjunction that will do for road bikes.

4. While I have as little patience as Jobst Brandt with the idea that a flexible, springy frame is somehow an advantage (see above about NO STEERING INPUTS), I'm big on the greater absorption (for want of a better word) of the smallest micro ripples by steel, which in turn leads to long-term comfort, and the absorption of the larger road irregularities of huge low-pressure tyres fitted to a correctly scaled stiff steel frame, which in turn leads to security. Comfort and security together make for surprising speed.

Andre Jute
And I look good in purple shorts!



FWIW, I agree with you WRT alu vs steel frames. I have one steel and
one CF. I had a few alu frame bikes but no longer.

But as any cyclist worth their salt will tell you, it's the shorts that
make the difference.

On 8/13/2014 2:39 PM, jbeattie wrote:
On Wednesday, August 13, 2014 8:30:31 AM UTC-7, Frank Krygowski wrote:

IIRC, the first I heard of a significant design choice based on

oversized tubes was in an article about Gary Klein. Supposedly, he was

an MIT engineering student who was excited to visit an exhibit of a

super-light bicycle; but was very disappointed to see that it had no

engineering innovation. They'd simply drilled and whittled conventional

parts down to stupid-light thicknesses.



He then started thinking about using aluminum frames, and it occurred to

him that aluminum's lower density would allow thicker (non-denting) tube

walls at larger diameters. So we got light & rigid Klein frames.

Cannondale and others copied the concept.

Klein copied the concept, and thus his mostly loosing patent infringement
suit against Cannondale. Harriet Fell, Sheldon Brown's wife, built a large
diameter aluminum frame bike before Klein, so did Bill Shook (American
Classic).
It's all on the interweb.

And I'm sure there were others, if not in aluminum, then in steel.

I haven't read much about the Klein-Cannondale lawsuit. But as someone
stated upthread, the properties of tubing related to its diameter (and
material density, modulus of elasticity etc.) have been known for
centuries. Heck, those were the basis of problems I'd assign to freshmen.

As such, I really dislike the idea of patents based on such obvious
"innovations." Should I be able to patent a thicker nail or a heavier
hammer?

Now everyone is chasing CF, which, like early aluminum, is claimed to
be too stiff, too soft, too light, too dangerous, etc., etc. Everyone
gets entrenched in their technology and claims the latest thing is bad --
and sometimes it is.

And sometimes it's magic! As a concertmaster/endorser says in my Shar
violin catalog that arrived today: "The Presto [carbon fiber] bow is
remarkable. I was amazed at the response, clarity and tone it produces.
This is a serious endorsement from me, as I have always shunned carbon
fiber bows due to their lack of an 'organic' feel. this bow feels and
responds like a first rate bow..."

I was waiting for the above endorser to say it's stiff AND compliant,
but I was disappointed. :-(

I figure that CF is not too bad, and it seems to be maturing as a
technology.
My CF frame beats the hell out of any steel frame I ever owned in terms of
weight versus stiffness, which matters when you're riding a 63cm frame
(Cannondale conventional DF geometry).

CF certainly allows a lot of customization of properties. I can see it
might pay off for a big guy, especially. At least, if it's treated
well. (For your sake, I hope it's not _really_ water soluble.)

For most people, though, the benefits of any bike tech improvements are
going to be very marginal. I strongly suspect the bathroom scale I
bought Monday is going to improve my cycling far more than a new frame
would.

--
- Frank Krygowski

On 13/08/14 20:54, John B. Slocomb wrote:
On Wed, 13 Aug 2014 13:19:36 +1000, James
wrote:

On 13/08/14 12:38, John B. Slocomb wrote:
On Tue, 12 Aug 2014 11:22:03 -0400, Frank Krygowski
wrote:

On 8/11/2014 11:00 PM, James wrote:
I had a bit of road rubbish flick up and dent the underside of the down
tube on my new road bike. (It's only done 45,000km). The dent was
probably 2-3mm deep, and had damaged the paint. There were a few other
scratches here and there, so I gave it a birthday, and had the dent
pulled out and the frame resprayed.

I'm curious about getting the dent pulled out. How did they do that?



In the down time, I completed building a training bike I'd started a
year ago. A 20 year old custom 853 lugged racing frame, with the same
wheels as my new bike.

The major difference is the frame tube diameter. The old frame having
the customary 1" tubes, where as the new bike frame has 1 1/8" and 1
1/4" oversize tubes.

I rode 166km on Saturday on the old bike, and then last night, 60km on
the new bike.

The difference in the way they ride is very obvious. The old bike feels
like a soft spring when I stand on the pedals, and I can watch the chain
rings wobble around while I pedal hard, even seated.

The new bike feels crisp and zippy underneath me. It feels like every
ounce of effort going into the pedals gets translated to the back wheel
and on to the road....

I prefer a stiff frame, too. But I note that Jan Heine, who (almost
single-handedly) publishes _Bicycle Quarterly_, likes a certain amount
of flex. He claims the flex somehow allows the bike to synchronize with
his pedal strokes (or something). He calls the action "planing," as
when certain types of power boats skim the surface, rather than floating.

Hard to tell if it's imaginary or not. His magazine has some
interesting tests and data from time to time, but his road tests greatly
emphasize how a bike feels to him - as is usually the case with road tests.

I would say that his choice of words is incorrect. A boat doesn't
plane due to a flexible frame. Quite the opposite perhaps :-)

But as the frame of a bicycle flexes under load and than returns to
its original position when the load is reduced it might be referred to
as "Springing". Which does sound sort of "cool". "I was just springing
along on my bike", "I shall just hop on my bicycle and spring away"
:-)



Sounds cool, but I don't think it helps. If you use muscle to bend a
spring and let it return by reducing the effort back to zero, a perfect
spring will return the energy put into it, but the returned energy
doesn't end up as calories in your muscles again. Instead your body
consumes energy as you bend and release the spring. I think similarly
when you flex a bicycle frame, the energy that went into flexing it
doesn't find it's way to increasing your kinetic energy forward on the
bike (some might, but certainly not all). More likely it is wasted
while your body deals with it.


No, a cyclist loads the spring but then the takes all the weight off
the pedal and the spring doesn't do any work on the "return stroke".

Unfortunately we do not take all the weight off instantaneously, and we
don't turn off the muscles instantaneously either. We try to pedal in
circles, such that torque is applied more evenly. But regardless, yes,
the energy isn't returned to us.


The only good thing that comes from spring in a bike frame is suspension
- but then slightly fatter tyres and less air pressure can achieve the
same effect on bitumen - better in fact, because it doesn't bounce the
whole think around. It's only when the bumps get really big that we
need to resort to shock absorbers, etc.

One wonders why skinny tube racing bikes were used for so long a
period. It is certainly not because engineers didn't know that a thin
large diameter tube is stiffer then a thin small diameter tube.


I think people were chasing lower weight as the priority.

--
JS

On 14/08/14 01:09, Frank Krygowski wrote:
On 8/12/2014 11:19 PM, James wrote:


Sounds cool, but I don't think it helps. If you use muscle to bend a
spring and let it return by reducing the effort back to zero, a perfect
spring will return the energy put into it, but the returned energy
doesn't end up as calories in your muscles again. Instead your body
consumes energy as you bend and release the spring. I think similarly
when you flex a bicycle frame, the energy that went into flexing it
doesn't find it's way to increasing your kinetic energy forward on the
bike (some might, but certainly not all). More likely it is wasted
while your body deals with it.

Certainly, James is right, that energy can't be put back into the
muscles. If bottom bracket flexibility helps at all, I think it must be
a very subtle mechanism. Jan Heine never, IIRC, explains a plausible
mechanism. For a long time, he just said something like "this bike
planes for me" with no explanation of the word "planes". It took me a
while to deduce the word's etymology.

But here's a potentially analogous situation: Walking while carrying
two heavy loads balanced on the ends of a flexible pole.
http://www.talkvietnam.com/2014/04/t...amese-culture/
Of course, there's practicality in having a wide load spaced away from
one's body, so it doesn't bang against one's legs. But many seem to
think a flexible pole makes carrying easier, somehow reducing the work
load.

This paper http://www.ncbi.nlm.nih.gov/pubmed/1757307 found no
reduction in oxygen consumption for a pole vs. a backpack. But it did
find less peak loads. Is there a chance that a certain amount of bottom
bracket flex would similarly reduce peak loads on the legs at the bottom
of the pedal stroke?

I have noticed that when I stand to climb a very steep hill, it feels
like my weight lands harshly on the pedals at the bottom of the pedal
stroke.

All the above is speculation. I don't claim to have this figured out.


An interesting analogy with the springy pole and walking. I can imagine
that higher peak loads are more fatiguing.

On a bike however, I don't think we have to behave the same, regardless
of the frame stiffness.

When your weight lands harshly on the pedals at the bottom of the pedal
stroke while standing and pedalling up a very steep climb, couldn't you
start to press down with the other leg a little earlier to start to
unload the leg that's near the bottom of the cycle?

I think we can control the peak loads even on a stiff frame, by altering
where and in what direction we apply pressure to the pedals and
handlebars, etc.

Perhaps it's another reason to pedal in circles rather than just
stomping down on the pedals - all the way to the bottom where downward
force does nothing to propel you forward.

--
JS

On 14/08/14 04:39, jbeattie wrote:

Klein copied the concept, and thus his mostly loosing patent
infringement suit against Cannondale. Harriet Fell, Sheldon Brown's
wife, built a large diameter aluminum frame bike before Klein, so did
Bill Shook (American Classic). It's all on the interweb.

Klein reinforced his stays with boron, so that was unique. I rode on
a Klein sponsored team back when he was working out of shed in San
Martin. Those early frames were really stiff compared to steel, but
they looked weird (IMO)and were super expensive. I couldn't afford
one and still liked the steel aesthetic. Plus, even as a big rider, I
could get a plenty stiff frame using SP, but it was just a boat
anchor by today's standards. I only made the switch to OS aluminum
after breaking my fourth or fifth steel frame and right when
Cannondale starting making a lower cost option to the Klein. I never
looked back.


Nice history lesson. Thanks.

I think oversized steel tubes will not break so easily as 1" tubes,
because the stresses should be lower. Frank might correct me if I'm wrong.

What can happen to any steel frame (perhaps not if it's stainless) is
corrosion, and a corrosion pit can be the catalyst for a crack to
develop. Chipped paint on a steel frame is your worst nightmare.

BTW, there was some frame engineering back then. The Exxon Graftek
in 1975. Speedwell and other Ti builders. Both of those were noodley
if not plain dangerous. Otherwise, it was just Italian versus
English, and your choice of butting patterns and wall thickness
(SP/SL/SLX, TSX (later)and all the 531 variants) Real changes came
later with shaping and new steel alloys that air hardened, etc. --
and I think may of those came about because OS aluminum was eating in
to the steel market.

Now everyone is chasing CF, which, like early aluminum, is claimed to
be too stiff, too soft, too light, too dangerous, etc., etc.
Everyone gets entrenched in their technology and claims the latest
thing is bad -- and sometimes it is. I figure that CF is not too
bad, and it seems to be maturing as a technology. My CF frame beats
the hell out of any steel frame I ever owned in terms of weight
versus stiffness, which matters when you're riding a 63cm frame
(Cannondale conventional DF geometry).


There is also now a blend of stainless steel and CFRP....

http://www.culturecycles.com/tag/kva...arbon-exogrid/

And available in production bikes here ...

http://www.maxway.com.tw/product.htm...=0&cid=2&id=77

I've asked for a price.

--
JS