jim beam <
[email protected]> writes:
> Tim McNamara wrote:
>> jim beam <[email protected]> writes:
>>
>>>Tim McNamara wrote:
>>>
>>>>jim beam <[email protected]> writes:
>>>>
>>>>
>>>>>Tim McNamara wrote:
>>>>>
>>>>>
>>>>>
>>>>>>The existence of the ejection force is not hypothetical and can
>>>>>>be readily demonstrated by anyone with a current front disk
>>>>>>brake. There is no necessity for the design to be such that it
>>>>>>creates an ejection force. It's as simple as that. The issue
>>>>>>of "threaded fasteners" is a secondary issue that is exploited
>>>>>>for obfuscation by the disk brake apologists. The ejection
>>>>>>force should not exist. Period. Its existence is proof of a
>>>>>>design flaw. Period.
>>>>>
>>>>>rubbish. by that argument, brake cables would never be used in
>>>>>tension, or clamped, cable outer could never be used in
>>>>>compression, frame tube could never be used to resist bending or
>>>>>tension or torsion, stems could never clamp onto a smooth tube,
>>>>>seat posts could never clamp into frames, chain rivets could
>>>>>never work in chain side plates... the whole point of
>>>>>engineering is that you work with the reality of your
>>>>>situation. <snip even less relevant malarkey than usual>
>>>
>>>>The difference, oh bottled one, is that the current design is an
>>>>optional one. There are better designs that could easily be
>>>>employed, designs that are tolerant of suboptimal conditions like
>>>>the common one of QRs that are not as tight as they ought to be,
>>>>perhaps because the rider doesn't have enough hand strength (which
>>>>might be one of the reasons they are riding a bike with disk
>>>>brakes, eh?), or dirt and mud interfering with getting full
>>>>clamping force, or perhaps even cyclic forces loosening the
>>>>skewer. Gasp!
>>>
>>>oh please, that's a straw clutch. cyclic forces loosening the
>>>skewer? show me. "it came loose, so it must have loosened" sounds
>>>just like my grandmother's car smash where she was pressing the gas
>>>instead of the brake.
>>
>> The issue of loosening threaded fasteners is well-known in
>> mechanical engineering. Perhaps you think that the laws governing
>> such things are different for bicycles? I notice that you tacitly
>> admit the other potential problems, though.
>
> that's ridiculous! how can we use any fastener in any application?
> do you want to weld the wheel to the frame? there's no reason a qr
> is any less suited to this application than a solid axle.
>
>> That the ejection force exists in the first place is a design flaw
>> that must be rectified.
>
> rubbish! how can you return to this ridiculous untruth repeatedly?
> just because there's load, it can't be used??? that's beyond
> stupid.
What's stupid and even unethical is your support for an easily
rectified design flaw that creates a serious risk to the safety of the
rider.
>> This is the primary issue. The industry can rectify it proactively
>> or they can rectify it as a result of litigation. Either way, it
>> will be rectified eventually.
>
> not without elimination of the bike. every single component has
> some kind of load. it's simply a matter of making the load less
> than the strength of the component and its fastening mechanism.
There are loads that are essential and loads that are not. The
ejection force created by current front disk brakes is not an
essential load, because the design can be easily changed to eliminate
it.
>>>>The red herrings you try to create are just that, precisely
>>>>because they are design necessities- there aren't a lot of other
>>>>ways to achieve those functions. Can't fly a plane without wings.
>>>>Pretty hard to pedal a bike without a chain. Pretty easy to stop
>>>>a bike with something other than disk brakes. There are a number
>>>>of other design options that would eliminate the design flaw that
>>>>results in the ejection force.
>>>
>>>nice try tim, but no cigar. wings can be internally braced or
>>>externally braced. internal bracing is favored for improved
>>>aerodynamics, but it requires a substantial compromise on the
>>>"design options" of much easier external bracing. i say again,
>>>engineering is all about reality. so far, this debate has precious
>>>little of that.
>>
>> The "engineering reality" is that the current trendy disk brake
>> design causes an ejection force on the front axle.
>
> rubbish! yes, there's force, but it's as relevant as saying that
> because crank arms have tensile loads on one surface and compressive
> on the other, the tensile surfaces should be eliminated! ridiculous
> statement.
You're once again engaging in obfuscation to try to hide the fact that
you seem not to have grasped the essential core issue under
discussion.
>> Given that the design can be easily changed to eliminate it, unlike
>> the forces on airplane wings or bicycle chains, the design must be
>> changed. It's really simple despite your attempts at obfuscation.
>
> it's not obfuscation tim, it's the truth. the reason society's
> gotten as far as it has today is because of the development of bulk
> materials [steels] that are good in tensile loading. without that,
> we'd have no modern structures, no modern weapons, no modern
> machinery. no bikes. the materials can take the load. get over it.
Except we're not talking about the *materials* taking the load, jim.
We're not talking about metals fracturing, despite your strange
attempts to divert the discussion into another dead end. We're
talking about the interface between materials.
>>>btw, have you ridden a bike with disks? what was your experience
>>>with them like?
>>
>> You've asked this before, jim. I found disk brakes to be grabby
>> and lacking modulation, and I'd really not have liked to use them
>> in a technical situation on a trail. These brake were Avids, as I
>> recall.
>
> maybe that explains some of your resistance to sense. Davids are
> **** for the exact reasons you cite, but that's no reason to condemn
> disk brakes that are any good.
This is another red herring of yours, jim. The issue isn't whether
the brakes work or whether I like them. The issue is that the brakes
try to push the front axle out of the dropout. All of your twisting
and dancing around doesn't alter the central facts.
>> Frankly I thought they offered no improvement and in some ways were
>> worse than properly set up cantilevers. They'd stop better than
>> rim brakes in mud, but IMHO it's irresponsible to be riding trails
>> when they are muddy so I don't see that as a useful benefit. Lever
>> force was lower than for sidepulls, cantilevers or V-brakes, so
>> disks might be helpful for people with weak hands, such as someone
>> who has some neuromuscular problem- I do see that as a real
>> benefit. The downside there is that people with weak hands are not
>> likely to be able to lock the skewers down tightly enough and thus
>> risk wheel ejection. That's an irresponsible risk for the
>> designers of the brakes and forks to have created. Eliminating the
>> ejection force is nearly trivial in terms of design and therefore
>> the manufacturers are ethically compelled to do so.
>
> that's an unbelievably naive statement - you have no concept of
> structure applications or materials whatsoever.
Neither do you, from what you've written. You seem to be unable to
see the forest because the trees are in your way. There is nothing
naive whatsoever about placing the safety of the user above the
convenience of the designer or the manufacturer. Indeed, that is
part of what engineers are supposed to do. Correcting the design to
eliminate the ejection force would be nearly trivial, and therefore it
should be done.
It's also too bad that you evince so little interest in the safety and
value of the folks most at risk for this problem, who are also the
people most likely to obtain a practical benefit from disk brakes.
