why clincher more pricey???

[jmaccelari]

 

My point shall reveal itself' date=' don't you worry about that. Just do your calculations. What other measurements can I make for you? As you said yourself, you don't need thousands of data points to do this properly. Lets complete the job.

 

[/quote']

Give me a chance. Actually doing the maths is more time consuming

than you burying your head in the sand and reciting "It isn't so 'cos

I say it isn't so...".

 

and please make your point - the suspense is killing me.

 

I've been asking for your point for 3 days now and you really don't

seem to be able to make one...

 

[GoLefty!!]

 

actually the term is "baited breath" or simply "baited" implying that you have nibbled on something used to lure you into a debate' date=' fight, skirmish etc etc.But we're getting into semantics here and that is detracting from the intention of the thread.[/quote']

 

 

 

actually it isn't, http://www.phrases.org.uk/meanings/bated-breath.htmlbut you're right, we digress...

 

 

ah ha, but this is starting to get a little smelly isn't it..

 

[Wyatt Earp]

The point is that our man thrives around being controversial, this is one way to ensure that the perception of superior knowledge is enforced.

 

 

[Johan Bornman]

 

Cut cut cut

 

It seems logical to me that even while riding at a constant speed' date=' a point on the rim is constantly accelerating and decelerating as it turns. It'll be going much faster than the bike when it passes the brakes and it'll be doing 0kmh for a split second when it touches the tar.

With this in mind, I ask whether a weight saving at the rim will be beneficial for a cyclist riding at a constant speed. [/quote']

 

Jules, from an aerodynamic point of view, your issue about the bottom part of the wheel standing still and the top part moving at twice the bike's speed has relevance, if not in MOI.  When considering the aerodynamics of a wheel, we know the bottom bit has zero aero drag and the top bit double the (relative) drag of one going at the same speed at the bike - at the 9 and 3 O'clock positions.

 

A proper aero simulation in a wind tunnel would thus require spinning wheels but this is probably completely irrelevant as we can assume that the two cancel each other out, give or take a little bit of air flow variance at the top and bottom of the wheel.

 

 

[jmaccelari]

 

 

 

 

 

 

OK - now that I've got it off my chest, let me try and explain to someone

who is clearly on the wrong track.

 

Read my lips: the actual figures do not matter. The concept remains

the same no matter what hub/spoke/nipple configuration you throw

at me.

 

The physics is true for every wheel. Even (and you may have a problem

getting this fact) - even the one in your hand.

 

So to continue:

 

Don't assume. I said ask and yo didn't ask that question. It is a 32-spoke wheel.

 

The number of spokes doesn't matter.

 

It just changes the final number a little little.

 

The actual value of the final number does not matter. It does not change

 

the basic physics.

 

 

My omission' date=' I'll go with the assumption.  But you have to ask if it is a wire bead or Kevlar bead, tubbie or clincher.

[/quote']

The exact mass and type (and even make - stick that to the Conti fans!)

does not matter.

 

It just changes the final number a little little.

 

The actual value of the final number does not matter. It does not change

the basic physics.

 

Exact geometry - my point exactly. You didn't ask. Do ask' date=' because it is important. I've only answered what you asked.

[/quote']

The exact geometry is not important. Get used to it. We have a pretty

good approximation to the MOI and any refinement will only change

the numbers by a few percent (even if it's 90% it doesn't matter).

 

It just changes the final number a little little.

 

 

The actual value of the final number does not matter. It does not

change the basic physics.

 

 

I(spokes) is about 5.53x10-3 kg/m^2

You were given I=m*L^2 / 3

 

Nice guess' date=' but you overlook the fact that the spokes are longer than the internal radius of the rim minus the outer radius of the hub. This implies what?

[/quote']

No I didn't smart arse. You gave me the lengths. I assumed even you

were capable of properly measuring a spoke length.

 

BTW, since you can't even do the basic sums, I made

and approximation that meant we could avoid using the parallel

axis theorem (bet you haven't heard of that one, Mr Smartypants!).

 

(The formula given is for when the spoke starts at the axle. We know

it doesn't - it starts on the outside of the hub. Bet you didn't spot

that one, hey?)

 

This states that:

I = 1/12 * m * L^2 + m * h^2

in our case h is 0.13 so we are out by 14% for the spokes (which

means we are out by 0.2%.

 

Wow! What are you going to prove with 0.2%?

 

Why are you suddenly so concerned by 0.2% when your initial reaction

was to throw 100% out of the window?

 

It just changes the final number a little little.

 

 

The actual value of the final number does not matter. It does not change

 

the basic physics.

 

 

Ask.

I don't need to. As I have stated before it's a pointless exercise.

 

Oop! You did it again.

 

 

Your son assumed that the nipples are perfect little tubes. They are in fact real nipples that are lillipop shaped. Not only their shape affects their weight bias but also the large blank bore on the small side.

Again we are talking a fraction of a percent. You are nit picking in

order to avoid the actual argument. If we exclude the nipples

entirely we change the result by less than 4%. This does not

change the basic argument.

 

It just changes the final number a little little.

 

 

The actual value of the final number does not matter. It does not

change the basic physics.

 

You need some more data points.

Ask.

 

 

I don't need to. As I have stated before it's a pointless exercise.

 

 

Is this a tubbie or a clincher? You need another few data points here methinks.

 

I don't care what type of tyre it is. The equations don't care.

 

This show just how pathetic your grasp of physics is. The tyre could

be a tubbie' date=' tubular, MTB, road... The physics doesn't care. The

physics holds true to all rotating bodies.

 

We are talking about bicycle wheels, but it could be anything from

a car's flywheel to a planet.

 

You are obfuscating the issue by raising irrelevancies. Stop trying to

shoot holes in the exact numbers (which you don't care about unless

it suits you) and try to shoot a hole in my argument.

 

I think you're adding this up too quickly. Wait for the other data points.

I don't need to. This moronic insistence has been dealt with above.

It just changes the final number a little little.

 

 

 

The actual value of the final number does not matter. It does not change

 

 

the basic physics.

 

 

 

 

If you need more info' date=' I'm here, armed with tape measure  scale and baited breath.

[/quote']

I don't need it, so sit there with your tape measure and make a point.

 

Either prove my argument is wrong or shut up because you are making

a complete idiot of yourself.

 

 

 

 

English is not my first language but I'm used to this type of ridicule. I imagine lots of my African countrymen are subject to similar sarcasm.

Not from me, because I respect them...

jmaccelari2010-01-10 10:45:14

[jmaccelari]

 

actually the term is "baited breath" or simply "baited" implying that you have nibbled on something used to lure you into a debate' date=' fight, skirmish etc etc.

[/quote']

Thansk for the English lesson!

 

But we're getting into semantics here and that is detracting from the intention of the thread.

We reached a conclusion' date=' so perhaps it is time to lock the thread and move on.

[/quote']

Mr Bornman is still trying to wriggle out of this one with irrelevancies.

 

debating for debating's sake serves for nothing more than penis waving. I don't know where you will go to settle that one as gravity and MOI of a penis can vary greatly depending on the state of excitement' date=' height above sea level, air pressure, water quality etc

 

[/quote']

It may be penis waving, but Mr Bornman wants us all to know exactly

how big his is!!!

 

[GoLefty!!]

well apparently the english lesson was incorrect anyway.

 

 

[Johan Bornman]

OK - now that I've got it off my chest' date=' let me try and explain to someone
who is clearly on the wrong track.

Read my lips: the actual figures do not matter. The concept remains
the same no matter what hub/spoke/nipple configuration you throw
at me.

The physics is true for every wheel. Even (and you may have a problem
getting this fact) - even the one in your hand.

[/quote']

 

No need to read your lips. My original method was after all a workaround to avoid the complex issues of measuring the actual MOI. Why do you assume I don't get that? I thought it was a rather elegant way of avoiding it but then....I would say that, after all, I am a ****.

 

The concept remains the same no matter what nipple spoke configuration I come up with. However, you insisted that I don't need "thousands of data points" to make this (your words) "very simple calculation."

 

The point is that you do need zillions (interpret that as you like) of data points to reach an accurate conclusion when calculating the two MOIs and comparing them.

 

To illustrate what I mean I'll list some of the considerations I originally came up when I approached the problem like Analitical Cycling (Kiwi) and the back of Spinnergy boxes does.

 

1) The hub is complex. At the very centre of its rotating parts are two sets of steel balls that rotate at half the wheel's rotational speed around the cone's circumference. We of course ignore their rotation around their own axis. A couple of data points there (races, bearings etc).

 

2) The hub is centre-dense and perimeter light. That has to be taken into consideration. At least three data points there.

 

3) The spokes sit a certain distance inside the hub - you wrongly assumed at the perimeter. The spokes, unless they are radial, cannot be factored in using their full length. You need multiple data points for this geometry alone. They exit the hub at a tangent and that angle has to be calculated. For that you need to know the number of spokes and the number of crossings. Futher, the spokes are not uniform. They have a complex elbow and head and, are butted. The butt is an even taper. The effect here is significant since the butt is 10% of the spoke's volume. How many data points to we need here, 10?

 

4) The nipples are complex. They are head-heavy and foot-light. A blank bore preceeds the threaded hole, which accentuates this effect. Further, they arrive at the rim at an angle. I may or may not want to discount this small variance but if I want to be pedantic, I'd do it. It is a simple trig problem. I'd say at least 6 data points here.

 

5) The rim is complex. A tubby would have its bias in a different place from a clincher. V-sections have a shape that may accentuate weight inside or out. Lets say 3 data points.

 

6) The tyre is complex. Steel or Kevlar bead will have an effect of the overall weight's bias to the inside or outside. Give me three data points.

 

I call this complex. If you don't, then so be it. Like you say, it doesn't make the problem more difficult, but it does require some thinking and understanding of the construction of the wheel which is as I've demonstrated, nowhere near an ideal wheel and a bit more involved than just plugging in a formula.

 

 

 

 

 

 

 

 

[jmaccelari]

 

well apparently the english lesson was incorrect anyway.

 

Oh my gawd!!! So I WAS WRONG!!!

 

Can I do a JB on this and continue haranguing you for 20 pages (so far)

so you go away and I can pretend I was right?

 

[Wyatt Earp]

 

well apparently the english lesson was incorrect anyway.

 

Oh my gawd!!! So I WAS WRONG!!!Can I do a JB on this and continue haranguing you for 20 pages (so far)so you go away and I can pretend I was right?

 

No need, your avatar is blushing.

[jmaccelari]

 

 

 

 

 

No need to read your lips.....

(tons of rehashed and irrelevant rubbish)

...

You DO miss the point entirely.

 

The point is that any wheel you care to describe, imagine, whatever

can be reduced in its relevant physical properties to an ideal wheel (a

hoop of a specific radius).

 

I never dissed your technique - I just stated that for the argument it is

irrelevant and you have gone off on a massive tangent about something

that is off topic. If this is your "killer blow", I'm sorry, but you just missed

and have hit yourself in your gyrating crotch.

 

Your numerical integration technique is valid, but it is impractical

and will lead to no difference in the conclusion. That was my point - no

more and no less.

 

So your reply above is completely irrelevant.

 

Sorry, Johan, but that's science. It's bigger than you...

 

You are also STILL avoiding the central issue of your bullsh*t statement

(and dissing of Kiwi to boot) that losing weight off the wheel has no effect

over losing it on the frame. You have been proved wrong and are making

no attempt at arguing this point.

 

Stick to the point and stop trying to divert attention away from your

(dare I say it) error...

 

Johan - you are fallible. Get used to it, dude.

jmaccelari2010-01-10 10:58:21

[GoLefty!!]

 

well apparently the english lesson was incorrect anyway.

 

Oh my gawd!!! So I WAS WRONG!!!

 

Can I do a JB on this and continue haranguing you for 20 pages (so far)

so you go away and I can pretend I was right?

 

 

I don't get out of bed for a debate/arguement of less than 30 pages, so please continue...

 

[Wannabe]

Geez, you guys are getting tedious.

Agree to disagree and move on.

[jmaccelari]

 

I think this thread needs a conclusion (sorry GoLefty!!).

 

eclipse posted a thread about carbon clinchers.

 

Kiwi then posted "So a 100 grams saved at the rim will have a much bigger

effect than a lighter frame for instance."

 

Johan then laid into Kiwi: "This old old-wive's tale refuses to die. If you do

the maths, and

believe me, it is not difficult stuff, you'll see that this story is

nonsense."

 

Kiwi then presented Johan with a mathematical proof (go to page 1).

 

Johan then tossed this out of the window (Newton turns in his grave):

"One place where you should not take physics lessons is from bicycle

company websites and from the back of bicycle product boxes."

 

What Johan forgot to say was that you should take the physics if it is

correct (even if you don't like it).

 

Johan then went on to intimidate everyone by asking for data to plug

into a formula (which remains secret to this day).

 

Johan then goes off topic calculating power and asking irrelevant

questions about times and so on - hoping people will lose interest and

bugger off..

 

Everyone is suitably impressed and Johan stares the Hub down...

 

Tumbleweed rolls across an empty street...

 

I am then asked offline and unaware of the thread to investigate the

topic. I look at a "generalised, ideal" wheel so I can prove the results

for all wheels that have ever and will ever exist. I prove that the "old

wive's tale" is true, albeit not a major factor.

 

I post this in the Hub with full derivations, explanations and

conclusions.

 

Johan gets upset with me disproving comments like: "I've just shown you

what a 200 gram difference makes. It doesn't

matter whether that is from

nipples at the hub or from carbon instead

of aluminium at the perimeter."

Accept it."

 

He's wrong again...

 

I tell him we can use simple maths to model the system and this will

have the same result as the most tedious (not complex) numerical

approximation (his tape & scale crap and thousands of measurement

points). The numbers may be slightly off, but the conclusion stands.

 

Back to obfuscation. I have proved he is wrong for every wheel in

existence, but Johan is going to prove me wrong. Instead of arguing

the original argument, he is going to show me how complex it

really is.

 

He has to give me the data because he is incapable of doing the

maths himself (even though I gave him the formulae).

 

I do some first level approximation for him, which will give a very

good approximation and still proves that lighter wheels save more

energy than a lighter frame.

 

He is not happy. He then says my modelling isn't accurate enough.

 

I say I don't care because no matter how accurate or inaccurate the

modelling is, it won't make any difference to the basic conclusion.

 

Johan then comes back with irrelevant nitty gritties and still refuses

to accept that no matter how the wheel is modelled, his original

attack on Kiwi's statement and subsequent proof are wrong.

 

So now we wait... with baited (sic) breath...

 

(The funny thing is, that from the things he has said, he seems to be using

the same equations I am, but cannot interpret them on a universal level

and just has to keep on plugging numbers in to prove the statement

for each wheel. That's a lot of wheels to go through...)

 

Oh. And on the way we amused, entertained and irritated a lot of

people.

 

Sorry eclipse, but I think Kiwi answered your question correctly on

page 1...

 

jmaccelari2010-01-10 11:44:29

[GoLefty!!]

[scrolls back to page 1 looking for an opening to eeck out another 9 pages of debate...]

[Johan Bornman]

Jmac, you clearly have a major beef with me and chose rudeness and insult as your weapon. You forgot to include in your one-sided summary the flaws in your ideal wheel calculation and your (acknowledged) misinterpretation of my statements. I have pointed them out to you without any comment other than the usual blustering.

 

You keep on harping about my "attack" on Kiwi. No such event happened. I am sometimes a bit robust in my replies but I have no malice towards the guy.

 

He quoted Cane Creek as a source to back up his statement and said:

 

Originally posted by Kiwi Cane Creek:   Physicists use the term Moment of Inertia (MOI) to describe the effects of mass during rotation. And MOI is one of the forces working against you every time you accelerate. More than 95% of the MOI associated with propelling a bicycle is attributable to the wheels. This means that gram for gram, your wheels are your bike?s most critical components. One of the ways our engineers minimize MOI is by locating Cane Creek spoke nipples at the hub. To understand how dramatically this affects acceleration, imagine if we moved the nipples to the traditional location at the rim: Given a nipple weight of 0.27 grams, the effect on the wheel?s MOI would be the same as if we?d replaced them with nipples weighing 48.55 grams.  <?: prefix = o ns = "urn:schemas-microsoft-com:office:office" /><?: PREFIX = O />

 

I retorted with:

 

"One place where you should not take physics lessons is from bicycle company websites and from the back of bicycle product boxes.

 

What Crane Creek forgot to tell you is that MOI also helps you keep you going once you stop accellerating. It is like the wind chill factor thing. In winter they say, "hell it is going to be cold today, not to even mention the wind chill factor." In summer they say, "hell it is going to be hot today" and then they forget to mention the wind chill factor.

 

Further, Crane Creek didn't bother to quantify the effect of a little bit of weight saving at the rim. Do it, you'll see it is miniscule."

 

Kiwi quoted a statement that a weight difference of 0.27 grams at the rim (of a mystery wheel), has an effect of 48.55 grams.

 

That had to be challenged since it is an old wive's tale.

 

If that is at the epicentre of your beef, get over it. That figure is nonsense.

 

As I showed, it does make a negligible difference. Negligible is the word I used and I calculated it for a real-world scenario.

 

In order to create a real-world scenario I need some accelleration figures which I attempted to measure myself. However, I found it difficult to do due to my bike computer's latency and thus asked for figures. These were volunteered from a Garmin's recording of a real race. I used those figures to calculate the difference.

 

As you said, there was nothing wrong with my calculation and I quantified "negligible." It is open to the reader's interpretation to define "negligible" and "old wive's tale".

 

With anticipated futility I ask you to stop the madness.

 

Dear Reader

 

Cane Creek's claims of 48.55 to 0.27 improvement are utter rubbish and hold no relevance to the real or imagined world of cycling. I cannot back off from that statement and will have to disagree strongly with whoever cites it.