WTB Suntour CYCLONE BB Spindle

Frank Krygowski writes:

On 8/26/2019 5:04 PM, Radey Shouman wrote:
Tom Kunich writes:

Frank, stop showing your engineering inability. Did I not talk about
the Octalink BB? Is that the same diameter? And since you seem to
think that mild steel and Chrome Moly have the same torsional strength
why do they make drive shafts on high performance cars out of chrome
moly instead of mild steal since the cost difference is 200%? They do
no increase the diameters.

It would help if you quoted the stuff you're objecting to. Frank's
point, if I understood it correctly, was that strength != stiffness.
Chalo commented on a lack of stiffness in some obsolete bottom bracket
format or another, not a lack of strength.

I believe Frank would say that CrMo and mild steel have approximately
the same stiffness, and also that he would be right.

Correct.

I don't think Tom understands the difference between strength and
stiffness. And as usual, he's misstating my points in general.

It's a bit counter-intuitive, when you think about it, that the scary,
overly flexible bottom bracket probably required a high strength steel,
while a comfortingly stiff one would not.

Tom Kunich writes:

On Monday, August 26, 2019 at 2:04:35 PM UTC-7, Radey Shouman wrote:
Tom Kunich writes:

Frank, stop showing your engineering inability. Did I not talk about
the Octalink BB? Is that the same diameter? And since you seem to
think that mild steel and Chrome Moly have the same torsional strength
why do they make drive shafts on high performance cars out of chrome
moly instead of mild steal since the cost difference is 200%? They do
no increase the diameters.

It would help if you quoted the stuff you're objecting to. Frank's
point, if I understood it correctly, was that strength != stiffness.
Chalo commented on a lack of stiffness in some obsolete bottom bracket
format or another, not a lack of strength.

I believe Frank would say that CrMo and mild steel have approximately
the same stiffness, and also that he would be right.

While it is easy to say that the Young's modulus of ferrous materials
is "about the same" it isn't the same and the higher grade materials
are indeed stiffer if not by much. But these higher grade materials
allowed for large improvements in power transfer.

They do tabulate Young's modululs for various steels, so it's true that
it's not constant. As you say, it does not vary much. Higher grade
materials allow a greater working stress, which can be very useful.

On Tuesday, August 27, 2019 at 9:13:57 PM UTC-7, Frank Krygowski wrote:

Explain. If you take a bottom bracket axle made of steel with yield strength
100,000 psi and replace it with an identical part made of steel with yield
strength 120,000 psi, will it transfer more power from the same rider?

Perhaps you'd like to explain to us why that would matter? How many people can cause distortion of the bottom bracket axle in either case?

On Monday, August 26, 2019 at 8:01:06 PM UTC-7, Frank Krygowski wrote:
I don't think Tom understands the difference between strength and
stiffness. And as usual, he's misstating my points in general.

I suspect he mostly understands things correctly, but does not state his
line of reasoning clearly, leaving out certain assumptions, and then
gets all up in arms when anybody dares to point out that what he's
written can be completely wrong under different prevailing assumptions.
The ensuing argument is then always either him dangling bits of his
conclusions for people to infer his assumptions from, or his inverting
the situation by applying his assumptions to statements made under
different assumptions, then calling out the incorrect conclusions that
result.


To wit:
Moreover hollowing the axle out also increases the rigidity of
the axle.

Appears to be an oversimplification of:

Hollowing the axle out allows increasing its outer diameter by negating
the weight penalty of a larger diameter solid axle. This increase in
outer diameter can more than make up for rigidity lost from hollowing,
yielding a more rigid axle.

The extended text, although a little convoluted, is entrely legitimate.
However, it leaves things in a different place (larger outer diameter)
than what a reasonable reading of the original sentance would (hollowed
out, no other subsequent changes as none are mentioned). Which hollowed
spindle should we assume in making a comparison? Tom tries to peg down
this ending place by immediately citing Octalink, but everybody's
already been thrown off in a different direction from the initial feint
and missing subsequent steps.

Luns Tee wrote:
On Monday, August 26, 2019 at 8:01:06 PM UTC-7, Frank Krygowski wrote:
I don't think Tom understands the difference between strength and
stiffness. And as usual, he's misstating my points in general.

I suspect he mostly understands things correctly, but does not state his
line of reasoning clearly, leaving out certain assumptions, and then
gets all up in arms when anybody dares to point out that what he's
written can be completely wrong under different prevailing assumptions.
The ensuing argument is then always either him dangling bits of his
conclusions for people to infer his assumptions from, or his inverting
the situation by applying his assumptions to statements made under
different assumptions, then calling out the incorrect conclusions that
result.


To wit:
Moreover hollowing the axle out also increases the rigidity of
the axle.

Appears to be an oversimplification of:

Hollowing the axle out allows increasing its outer diameter by negating
the weight penalty of a larger diameter solid axle. This increase in
outer diameter can more than make up for rigidity lost from hollowing,
yielding a more rigid axle.

The extended text, although a little convoluted, is entrely legitimate.
However, it leaves things in a different place (larger outer diameter)
than what a reasonable reading of the original sentance would (hollowed
out, no other subsequent changes as none are mentioned). Which hollowed
spindle should we assume in making a comparison? Tom tries to peg down
this ending place by immediately citing Octalink, but everybody's
already been thrown off in a different direction from the initial feint
and missing subsequent steps.


Agreed. If we could get everyone in the same room, with a white board, a
moderator, and a big hulking guy with a club to maintain order, we could
probably come to a lot more agreement.

On 8/28/2019 11:51 AM, Tom Kunich wrote:
On Tuesday, August 27, 2019 at 9:13:57 PM UTC-7, Frank Krygowski wrote:

Explain. If you take a bottom bracket axle made of steel with yield strength
100,000 psi and replace it with an identical part made of steel with yield
strength 120,000 psi, will it transfer more power from the same rider?

Perhaps you'd like to explain to us why that would matter? How many people can cause distortion of the bottom bracket axle in either case?

Sheesh! Tom, that is precisely the point!

It was YOU who claimed "But these higher grade materials allowed for
large improvements in power transfer." That's what I was responding to.
Now you seem to be arguing with yourself!

Care to explain why you said that in the first place? What on earth were
you thinking?

--
- Frank Krygowski

On Thursday, August 29, 2019 at 12:44:33 PM UTC-7, Frank Krygowski wrote:
On 8/28/2019 11:51 AM, Tom Kunich wrote:
On Tuesday, August 27, 2019 at 9:13:57 PM UTC-7, Frank Krygowski wrote:

Explain. If you take a bottom bracket axle made of steel with yield strength
100,000 psi and replace it with an identical part made of steel with yield
strength 120,000 psi, will it transfer more power from the same rider?

Perhaps you'd like to explain to us why that would matter? How many people can cause distortion of the bottom bracket axle in either case?

Sheesh! Tom, that is precisely the point!

It was YOU who claimed "But these higher grade materials allowed for
large improvements in power transfer." That's what I was responding to.
Now you seem to be arguing with yourself!

Care to explain why you said that in the first place? What on earth were
you thinking?

--
- Frank Krygowski

I always wondered how they measured the effect of BB (shell or axle) flex and power output. Power is transmitted from the pedal to the arm to the spider to the ring to the chain -- as the mechanism is rotating on the BB axle. You would have to have one of those complicated equations with fancy symbols to calculate the contribution of flex in the BB axle or shell!

I know it is a big marketing point, but I don't recall going any faster when I went from a PW square drive to an Octalink on the same bike.

-- Jay Beattie.

On 8/29/2019 4:44 PM, jbeattie wrote:
On Thursday, August 29, 2019 at 12:44:33 PM UTC-7, Frank Krygowski wrote:
On 8/28/2019 11:51 AM, Tom Kunich wrote:
On Tuesday, August 27, 2019 at 9:13:57 PM UTC-7, Frank Krygowski wrote:

Explain. If you take a bottom bracket axle made of steel with yield strength
100,000 psi and replace it with an identical part made of steel with yield
strength 120,000 psi, will it transfer more power from the same rider?

Perhaps you'd like to explain to us why that would matter? How many people can cause distortion of the bottom bracket axle in either case?

Sheesh! Tom, that is precisely the point!

It was YOU who claimed "But these higher grade materials allowed for
large improvements in power transfer." That's what I was responding to.
Now you seem to be arguing with yourself!

Care to explain why you said that in the first place? What on earth were
you thinking?

--
- Frank Krygowski

I always wondered how they measured the effect of BB (shell or axle) flex and power output. Power is transmitted from the pedal to the arm to the spider to the ring to the chain -- as the mechanism is rotating on the BB axle. You would have to have one of those complicated equations with fancy symbols to calculate the contribution of flex in the BB axle or shell!

I know it is a big marketing point, but I don't recall going any faster when I went from a PW square drive to an Octalink on the same bike.

Not to resurrect an argument, but just to remind people:

A few years ago here, someone linked to a magazine article where they
had young modern racers do a comparison test of a 1980s or 1990s racing
bike vs. an up to date, modern rigid-yet-compliant, many-more-speeds,
STI equipped, more aero carbon frame racing bike. The test consisted of
repeated runs over a long steady climb.

The young test pilots were indeed faster on the new bikes, and said
everything about the new bike was much better except perhaps the saddle.
They said they were afraid to take their hands off the hoods to shift
the old bike. And yes, they said the rigidity was much better for power
transfer. It "proved" that all of the new technology was the bees knees.

Except the improvement in climbing speeds was precisely what would have
been predicted by just the difference in bike weight. All the other
factors had no demonstrable effect on speed.

--
- Frank Krygowski

On Thursday, August 29, 2019 at 12:44:33 PM UTC-7, Frank Krygowski wrote:
On 8/28/2019 11:51 AM, Tom Kunich wrote:
On Tuesday, August 27, 2019 at 9:13:57 PM UTC-7, Frank Krygowski wrote:

Explain. If you take a bottom bracket axle made of steel with yield strength
100,000 psi and replace it with an identical part made of steel with yield
strength 120,000 psi, will it transfer more power from the same rider?

Perhaps you'd like to explain to us why that would matter? How many people can cause distortion of the bottom bracket axle in either case?

Sheesh! Tom, that is precisely the point!

It was YOU who claimed "But these higher grade materials allowed for
large improvements in power transfer." That's what I was responding to.
Now you seem to be arguing with yourself!

Care to explain why you said that in the first place? What on earth were
you thinking?

--
- Frank Krygowski

Do you understand that there is a difference between the average sports rider and a pro racer where that flexing DOES cause a difference?

On Thursday, August 29, 2019 at 1:44:10 PM UTC-7, jbeattie wrote:
On Thursday, August 29, 2019 at 12:44:33 PM UTC-7, Frank Krygowski wrote:
On 8/28/2019 11:51 AM, Tom Kunich wrote:
On Tuesday, August 27, 2019 at 9:13:57 PM UTC-7, Frank Krygowski wrote:

Explain. If you take a bottom bracket axle made of steel with yield strength
100,000 psi and replace it with an identical part made of steel with yield
strength 120,000 psi, will it transfer more power from the same rider?

Perhaps you'd like to explain to us why that would matter? How many people can cause distortion of the bottom bracket axle in either case?

Sheesh! Tom, that is precisely the point!

It was YOU who claimed "But these higher grade materials allowed for
large improvements in power transfer." That's what I was responding to.
Now you seem to be arguing with yourself!

Care to explain why you said that in the first place? What on earth were
you thinking?

--
- Frank Krygowski

I always wondered how they measured the effect of BB (shell or axle) flex and power output. Power is transmitted from the pedal to the arm to the spider to the ring to the chain -- as the mechanism is rotating on the BB axle. You would have to have one of those complicated equations with fancy symbols to calculate the contribution of flex in the BB axle or shell!

I know it is a big marketing point, but I don't recall going any faster when I went from a PW square drive to an Octalink on the same bike.

-- Jay Beattie.

Just five years ago I could tell the difference in flex between an ISO BB and an Octalink. Today I can't. Five years ago when sprinted for a light I could hit almost 40 mph. Today I have trouble getting over 20.

So it doesn't matter what I'm using now but it did only 5 years ago. There is a local hill that I climb coming back from an area where there are many courses. 5 years ago I could go over its 3% grade at 25 mph. Today, it's 8 mph. This is all pretty shocking to me that I would change that much that fast. Of course in two months I'll be 75 but I wouldn't think there would be such a dramatic difference between 70 and 75.