J
jim beam
Guest
Michael Press wrote:
> In article
> <[email protected]>,
> Mark McNeill <[email protected]> wrote:
>
>
>>Response to Tony Raven:
>>
>>>On a normal nut the ratio of nut diameter to thread diameter is a lot
>>>lower than the QR nut so ease of tightening and releasing will be
>>>misleading as the turning leverage is much greater on the QR nut.
>>
>>That's all very well; but it doesn't address the point I was making, or
>>at any rate *thought* I was making.
>>
>>
>>
>>>No I don't but the onus is on those proposing that they behave
>>>differently to show it to be so.
>>
>>Yes indeed.
>>
>>I'm not an engineer [and those who think that only engineers should post
>>opinions on this matter may here allow their attention to wander ;-)],
>>but it doesn't seem to me at all unlikely firstly that some QRs may be
>>liable to loosening under prolonged/severe vibration, even when the
>>manufacturer's instructions are followed, and secondly that the force
>>acting on a brake disk may eject a loosened wheel.
>>
>>I can see the chain of reasoning; but there seems for the moment to be a
>>dearth of real-world measurement and observation, and not only on the
>>"plaintiffs'" side. As you say, it's up to them to make their case: but
>>on the other hand there's surely an onus on designers and manufacturers
>>to ensure that their products are safe, which requires an understanding
>>of all the forces involved. If I was in the population at risk, I'd
>>definitely be curious to see evidence that they do. ;-)
>
>
> From what you understand of the theory, consider this
> proposed experiment.
>
> Take a bicycle equipped with a disc caliper mounted on the
> back of the fork. Loosen the quick release clamp until it
> is barely engaged. Walk the bicycle at a brisk pace, then
> apply the front brake.
>
michael, why are you ignoring my post on this challenge? i did this
yesterday. the fork was retained by the lawyer lips. were you
expecting anything else to happen? if so, why?
> In article
> <[email protected]>,
> Mark McNeill <[email protected]> wrote:
>
>
>>Response to Tony Raven:
>>
>>>On a normal nut the ratio of nut diameter to thread diameter is a lot
>>>lower than the QR nut so ease of tightening and releasing will be
>>>misleading as the turning leverage is much greater on the QR nut.
>>
>>That's all very well; but it doesn't address the point I was making, or
>>at any rate *thought* I was making.
>>
>>
>>
>>>No I don't but the onus is on those proposing that they behave
>>>differently to show it to be so.
>>
>>Yes indeed.
>>
>>I'm not an engineer [and those who think that only engineers should post
>>opinions on this matter may here allow their attention to wander ;-)],
>>but it doesn't seem to me at all unlikely firstly that some QRs may be
>>liable to loosening under prolonged/severe vibration, even when the
>>manufacturer's instructions are followed, and secondly that the force
>>acting on a brake disk may eject a loosened wheel.
>>
>>I can see the chain of reasoning; but there seems for the moment to be a
>>dearth of real-world measurement and observation, and not only on the
>>"plaintiffs'" side. As you say, it's up to them to make their case: but
>>on the other hand there's surely an onus on designers and manufacturers
>>to ensure that their products are safe, which requires an understanding
>>of all the forces involved. If I was in the population at risk, I'd
>>definitely be curious to see evidence that they do. ;-)
>
>
> From what you understand of the theory, consider this
> proposed experiment.
>
> Take a bicycle equipped with a disc caliper mounted on the
> back of the fork. Loosen the quick release clamp until it
> is barely engaged. Walk the bicycle at a brisk pace, then
> apply the front brake.
>
michael, why are you ignoring my post on this challenge? i did this
yesterday. the fork was retained by the lawyer lips. were you
expecting anything else to happen? if so, why?