Misunderstood terminology

General cycling advice ( NOT technical ! )
tatanab
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Re: Misunderstood terminology

Postby tatanab » 18 Mar 2018, 1:34pm

Mick F wrote:
sjs wrote:
Mick F wrote:Torque vs Power.

From my rudimentary knowledge, torque is turning force, and power is torque multiplied by time.

Am I correct?


No!
Well, come on then ............. :wink:

Not maths, just plain simple English.
Power is torque times rpm. There can be no time element in power because I can put out 100 Watts for an hour or for 10 hours, it is still 100 watts.

tatanab
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Re: Misunderstood terminology

Postby tatanab » 18 Mar 2018, 1:42pm

Many of the misunderstandings we see on this forum I would generally think are by new riders or people who simply do not know. Cassette and freewheel for example; and a seat tube being described as a down tube for another.

There are errors in some books written by or about professional riders. I know that the gear inches thing occurs in a couple of accounts, I just cannot recall which books.

Some misunderstandings are harder to fathom - such as the work colleague a few years ago who insisted that "evens" was a different speed according to the distance being raced. He understood that it was 20 mph at 10 miles, but thought it was 18mph at 25 miles, above that he did not know. It was a few years of time trialling before he accepted that "evens" is always 20mph.

rotavator
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Re: Misunderstood terminology

Postby rotavator » 18 Mar 2018, 2:04pm

Torque vs Power.

From my rudimentary knowledge, torque is turning force, and power is torque multiplied by time.

Am I correct?

From what I remember from my school days:

Torque is force applied at a distance (e.g from pedal axis to crank axis), measured in Nm,

Power is the rate of doing work, measured in watts = J/s. Energy and work are measured in joules (or kWh etc).

I am not sure how torque and power are related but at steady rate, power = force times velocity

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[XAP]Bob
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Re: Misunderstood terminology

Postby [XAP]Bob » 18 Mar 2018, 2:41pm

rotavator wrote:
Torque vs Power.

From my rudimentary knowledge, torque is turning force, and power is torque multiplied by time.

Am I correct?

From what I remember from my school days:

Torque is force applied at a distance (e.g from pedal axis to crank axis), measured in Nm,

Power is the rate of doing work, measured in watts = J/s. Energy and work are measured in joules (or kWh etc).

I am not sure how torque and power are related but at steady rate, power = force times velocity


It's similar in torque. But since the force is angular, so is the velocity. Power = torque * rpm
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Mick F
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Re: Misunderstood terminology

Postby Mick F » 18 Mar 2018, 2:52pm

I was sort of right then.
Power is torque multiplied by speed of rotation.
Mick F. Cornwall

David9694
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Re: Misunderstood terminology

Postby David9694 » 18 Mar 2018, 2:56pm

Internet forum contributor’s annual appraisal form:

Looking at the appraisee’s results for the past 12 months, managers should use the “pointless” scoring system in relation to the performance criteria below.

Scoring 1= top performer, 2 = solid, 3= middle of the road, 4 = you,re slipping, 5 = performance counselling referral

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brynpoeth
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Re: Misunderstood terminology

Postby brynpoeth » 18 Mar 2018, 5:34pm

nirakaro wrote:It's the nature of the journalist's job that they're constantly writing about subjects they don't know much about. If I read an article about anything I have some expertise in, I'll find errors in it. And if there are any numbers or sums – they're invariably wrong!

True but
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These experts should be recruited from members of these fora :)
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sjs
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Re: Misunderstood terminology

Postby sjs » 18 Mar 2018, 6:45pm

[XAP]Bob wrote:
rotavator wrote:
Torque vs Power.

From my rudimentary knowledge, torque is turning force, and power is torque multiplied by time.

Am I correct?

From what I remember from my school days:

Torque is force applied at a distance (e.g from pedal axis to crank axis), measured in Nm,

Power is the rate of doing work, measured in watts = J/s. Energy and work are measured in joules (or kWh etc).

I am not sure how torque and power are related but at steady rate, power = force times velocity


It's similar in torque. But since the force is angular, so is the velocity. Power = torque * rpm


Power (W) = torque (Nm) X rpm / 60 (to get to revs per second) X 2 Xpi, because torque = force X radius so power is force X speed of foot

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[XAP]Bob
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Re: Misunderstood terminology

Postby [XAP]Bob » 18 Mar 2018, 7:14pm

Should have said proportional to, but since I didn't specify units at all ;)
A shortcut has to be a challenge, otherwise it would just be the way. No situation is so dire that panic cannot make it worse.
There are two kinds of people in this world: those can extrapolate from incomplete data.

Bmblbzzz
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Re: Misunderstood terminology

Postby Bmblbzzz » 18 Mar 2018, 7:53pm

tatanab wrote:Some misunderstandings are harder to fathom - such as the work colleague a few years ago who insisted that "evens" was a different speed according to the distance being raced. He understood that it was 20 mph at 10 miles, but thought it was 18mph at 25 miles, above that he did not know. It was a few years of time trialling before he accepted that "evens" is always 20mph.

I know (because I've gathered from things said and written) that evens is 20mph, but I don't understand the concept that lies behind the figure. What does it represent? Why is it 20mph? If, as I vaguely think, it represents a "decent minimum" time trial speed, then I can't understand why it does not change with distance (or even as average times drop compared to historic standards).

drossall
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Re: Misunderstood terminology

Postby drossall » 18 Mar 2018, 8:29pm

Possibly because what actually varies with distance is the speed differential by which a good rider can beat evens, but beat evens they always do, so evens represents more of a speed that can be kept up by a fit rider over considerable differences, without actually going into racing effort.

I wish :roll:

drossall
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Re: Misunderstood terminology

Postby drossall » 18 Mar 2018, 8:30pm

Si wrote:My pet cringe is people who claim that a single speed or fixed bike doesn't have gear!

+1. Involves a complete misunderstanding of what gearing is. And raises the obvious question of why removing one gear from a two-gear bike would leave it with no gears, in defiance of all normal mathematics.

Although it's an easy colloquialism to slip into.

brynpoeth
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Re: Misunderstood terminology

Postby brynpoeth » 18 Mar 2018, 8:42pm

drossall wrote:
Si wrote:My pet cringe is people who claim that a single speed or fixed bike doesn't have gear!

+1. Involves a complete misunderstanding of what gearing is. And raises the obvious question of why removing one gear from a two-gear bike would leave it with no gears, in defiance of all normal mathematics.

Although it's an easy colloquialism to slip into.

If has no 'boite de vitesses', French for 'box of speeds', gearbox
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drossall
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Re: Misunderstood terminology

Postby drossall » 18 Mar 2018, 8:56pm

Quite, yes, no gear mechanism, gearbox, variable gears, or whatever, but it still has a gear.

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foxyrider
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Re: Misunderstood terminology

Postby foxyrider » 18 Mar 2018, 10:06pm

Bmblbzzz wrote:
tatanab wrote:Some misunderstandings are harder to fathom - such as the work colleague a few years ago who insisted that "evens" was a different speed according to the distance being raced. He understood that it was 20 mph at 10 miles, but thought it was 18mph at 25 miles, above that he did not know. It was a few years of time trialling before he accepted that "evens" is always 20mph.

I know (because I've gathered from things said and written) that evens is 20mph, but I don't understand the concept that lies behind the figure. What does it represent? Why is it 20mph? If, as I vaguely think, it represents a "decent minimum" time trial speed, then I can't understand why it does not change with distance (or even as average times drop compared to historic standards).

My understanding is that it refers to taking an even number of minutes to cover 25 miles when anything even approaching an hour was rare! So evens is always 3min/mile. So 30mins for a 10, 1.15 for 25, 2.30 for 50 and 5.00 for 100 miles. I never questioned this as my grandfather who was racing in the 30's always referred to evens in those terms as did my parents and everyone else I came into contact with in riding TT's over a 3 decade period.

I think the terms used today are fast and flippin' fast!
Convention? what's that then?
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