On Feb 9, 6:25 pm, jim beam <
[email protected]> wrote:
> [email protected] wrote:
> > On Feb 9, 4:05 pm, jim beam <[email protected]> wrote:
> >> [email protected] wrote:
> >>> In a previous discussion on this, I gave torque readings for a real
> >>> nylok nut and a QR nut. Again, the QR nut's resistance was negligible
> >>> by comparison. I'm sure Carl can look up that post.
> >> are you saying that the nylon retainer has no effect?
>
> > Certainly, no practical effect. They are not intended nor designed
> > for that purpose.
>
> no practical effect quantified how? and if it's not there for a
> purpose, what's it there for? across all brands and models.
The weak nylon teeth in a QR's nut are there so when you spin the nut
by hand, it maintains adjustment until the QR is properly clamped.
That's all.
Any frictional anti-rotation device that can be twisted by two fingers
is NOT going to prevent loosening under heavy vibration. (Good grief,
have you _never_ used a real Nylok nut? Have you _never_ worked on
machines bigger than bicycles?)
> >> and what about serrations?
>
> > They may help for a time.
>
> so that's "negligible"???
Depends on the amount of time, and the consequences of them not
working. How would you feel about a parachute harness that held you,
oh, till you were about halfway to the ground?
> > But the limitations of similar features on
> > industrial nuts and bolts are fairly well known.
>
> yeah, they're not locking wire, but what are we trying to achieve here?
We're trying to achieve a front end design that will never eject the
front wheel when a user has properly installed equipment sold as
adequate for its intended use, and used it in the intended manner.
Seems reasonable to me.
> if they're sufficient for the job, and statistics indicate they are,
> what else do we urgently need to achieve?
I think you're defiining "the job" rather loosely. I don't doubt that
standard QR hardware plus lawyer lips are adequate for disk brakes in
normal road riding or light off-road. And of course, we know that
sort of riding predominates the "statistics."
But the hardware in question is advertised as suitable for really
rough, aggressive riding. I believe that, if we could examine
statistics for those bikes used on long, rough, hard-braking
downhills, the statistics would be damning. You'll note that's the
type of ride that generates almost all the complaints.
> > But so far, nobody seems to be saying every
> > bike ridden by every rider exhibits evidence of the problem. It seems
> > to happen only under certain circumstances.
>
> sure - not tightening the skewer properly....
>
> but all this is ridiculous nonsense until operator error can be
> eliminated from the stats.
Why not read the accounts here
http://www.ne.jp/asahi/julesandjames/
home/disk_and_quick_release/#support
and tell us what the operator error was in each of those instances?
Or (for just one other example) this one I've quoted:
"Author: SteveM
Date: 30/03/03 19:59
"I had a scary experience of this sort yesterday and this explanation
works for me, I got to the bottom of the very twisty/bermy decsent at
Glentress, the one just before Delerverance, I thought that I had been
dropping like a muppet, even worse than normal, and had just put it
down to the fact that Lucy was buzzing my back tyre and that had put
me off, as we all set off again I realised the front was all floppy
and glanced down to see my Hope Steel QR had completley opened up, I
know for a fact it had been tight at the start of the ride because I
had heard the rumours about Russ's accident and have been a little
paranoid ever since so had checked it in the carpark ?, this QR is one
of the older designs BTW."
If someone is actually afraid of this happening, therefore double
checks, yet still experiences the problem, it must require an uncommon
degree of user skill to prevent your hypothetical user error!
IOW, it sounds like you're claiming the designer's defense is: "All he
did was follow the instructions. He should have done much more."
I don't think that defense works in product liability cases!
- Frank Krygowski