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Power Torque vs Ultra Torque

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Tom Kunich

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May 21, 2021, 8:24:51 PM5/21/21
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I'm trying to figure out why they have ultra-torque. Ultra-Torque cranks weigh nearly exactly the same as Power Torque cranks. It certainly couldn't be any stiffer. with a Hertz connection in the middle of the Record crank vs. a one piece shaft on the Centaur.

Does anyone have any idea what the hell was going through Campy's mind to make cranks with shafts in two pieces?

AMuzi

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May 21, 2021, 8:50:03 PM5/21/21
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On 5/21/2021 7:24 PM, Tom Kunich wrote:
> I'm trying to figure out why they have ultra-torque. Ultra-Torque cranks weigh nearly exactly the same as Power Torque cranks. It certainly couldn't be any stiffer. with a Hertz connection in the middle of the Record crank vs. a one piece shaft on the Centaur.
>
> Does anyone have any idea what the hell was going through Campy's mind to make cranks with shafts in two pieces?
>


The elegant Hirth joint UT Crank obviates the dreaded pinch
bolts on one arm.

http://www.yellowjersey.org/photosfromthepast/HIRTH.JPG

Many industrial applications besides bicycle cranks:

http://moderncnc.com/v-tooth/hirthcouplings.html

--
Andrew Muzi
<www.yellowjersey.org/>
Open every day since 1 April, 1971


jbeattie

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May 21, 2021, 9:47:39 PM5/21/21
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On Friday, May 21, 2021 at 5:50:03 PM UTC-7, AMuzi wrote:
> On 5/21/2021 7:24 PM, Tom Kunich wrote:
> > I'm trying to figure out why they have ultra-torque. Ultra-Torque cranks weigh nearly exactly the same as Power Torque cranks. It certainly couldn't be any stiffer. with a Hertz connection in the middle of the Record crank vs. a one piece shaft on the Centaur.
> >
> > Does anyone have any idea what the hell was going through Campy's mind to make cranks with shafts in two pieces?
> >
> The elegant Hirth joint UT Crank obviates the dreaded pinch
> bolts on one arm.
>
> http://www.yellowjersey.org/photosfromthepast/HIRTH.JPG
>
> Many industrial applications besides bicycle cranks:
>
> http://moderncnc.com/v-tooth/hirthcouplings.html

Many cranks use some sort of fixing bolt for the left arm and not pinch bolts, e.g. SRAM, FSA, Praxis. You can obviate the dreaded pinch bolt without adopting the elegant Hirth joint -- which, to me, seems unnecessarily complicated, particularly when it comes to bearing changes.

-- Jay Beattie.


Lou Holtman

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May 22, 2021, 3:11:06 AM5/22/21
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Op zaterdag 22 mei 2021 om 02:24:51 UTC+2 schreef cycl...@gmail.com:
> I'm trying to figure out why they have ultra-torque. Ultra-Torque cranks weigh nearly exactly the same as Power Torque cranks. It certainly couldn't be any stiffer. with a Hertz connection in the middle of the Record crank vs. a one piece shaft on the Centaur.
>
> Does anyone have any idea what the hell was going through Campy's mind to make cranks with shafts in two pieces?

Because in a proper mechanical design the bearings should have a press fit on the shaft in that application. One of the first lesson for a mechanical engineer. I saw more that one ruined Shimano cranks because they 'violated' that design rule. Mainly where a lot of dirt (ATB) is involved. Good advice there is to remove and check regularly and replace the bearings if there is any doubt. They are cheap.

Lou

jbeattie

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May 22, 2021, 11:29:26 AM5/22/21
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You would also have to see a lot of ruined SRAM, FSA, Praxis, Easton, etc., etc. Campagnolo is alone with its design approach. It may be better, but its also pretty Byzantine, and it is probably better in a way that makes no difference to most riders.

-- Jay Beattie.

Frank Krygowski

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May 22, 2021, 12:36:47 PM5/22/21
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On 5/22/2021 11:29 AM, jbeattie wrote:
>
> Campagnolo is alone with its design approach. It may be better, but its also pretty Byzantine, and it is probably better in a way that makes no difference to most riders.

:-) That last phrase is a good one, and applies so often!

Some people need to write it on the blackboard 100 times.


--
- Frank Krygowski

Lou Holtman

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May 22, 2021, 12:45:12 PM5/22/21
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Op zaterdag 22 mei 2021 om 17:29:26 UTC+2 schreef jbeattie:
Tom asked a question I gave an answer as an engineer. We have a discussion at work about stepper motors. One type has two loose fittings for easy assembling; on axle and in the housing, and the other has a press fit on the axle and a loose fit in the housing like it should. The first is 5 euro and the second is 7 euro. The 'accountants' are asking if the first one is not 'good enough'. Fair question. I say 'no'. They ask 'why not'. I say ' in an application were they drive a timing belt with a radial load (tension of the timing belt) that is not a proper design. The asked 'why not?'. At that time I lose my patient and tell them to do their work and I do mine. It is my design end of discussion. But they keep trying. At some point a younger engineer will give in and a service technician has to replace the motor. A service visit costs 200-300 euro. Most of the time the customer has to pay for that, instead of that 'accountant'. He will be pissed if he knew the whole story and would have gladly paid the extra 2 euro for the right type of motor. Repair of my wash dryer cost me 200 euro for a crappy designed heater and a 'Chinese' quality capacitor. Most people can not do that repair and will have bought a new one or let a service technician do the repair. I'm sure it would cost them 400 euro. We have to get rid of this kind of thinking.


Lou

Tom Kunich

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May 22, 2021, 4:38:10 PM5/22/21
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I was offered a job a month or so ago and it was making a laser surgery device for eye surgery. When I questioned the project manager about how he intended to control the laser he said with a direct drive stepping motor and I turned them down on the spot. Stepping motors USUALLY have overshoot and since this device controlled the angle of the laser, by the time you got out to where the cutting occurred the overshoot could be a hundredth of an inch and you cannot accomplish accurate surgery with such a thing. It is possible to have stepping motors with brakes to prevent overshoot and others that step slowly enough that you can hold them very accurately under 100% power but if the project leader doesn't understand that you're in trouble.

AMuzi

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May 22, 2021, 5:20:36 PM5/22/21
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Steel is a crystalline lattice. Did you mean 'crystal slip'
maybe?

https://www.engineeringenotes.com/metallurgy/metal-deformation/deformation-of-metals-and-its-types-metallurgy/41673

Tom Kunich

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May 22, 2021, 6:19:01 PM5/22/21
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Yes, but the size of the crystals varies with the treatment. Rapid quenching causes the smallest grains of crystals to form and annealing causes them to flow around and misalign with one another. You can add other metals to the Steel to cause the crystal structure to make smaller and hence denser grains. This is an entire science that has been around for 400 years at least. And they still make new discoveries all the time.
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