Disc brake front wheel ejection: fact or fantasy?

Alex Bird wrote:

This is my first post to this group, sorry it's a bit grim.
I saw a tv programme 3-4 years ago here in the uk, about a kid in the
west-country (SW England). His front wheel came loose and _somehow_
the forks ended up in the back of his skull. They showed the x-rays,
a few more millimetres and he would have been dead. Yes, he was fine,
after some medical attention. I think I've checked my quick release
every time I've got on my bike since I saw that...

Not quite the same thing. He popped a wheelie off a kerb, the wheel
fell out, chucked him over the bars and the bike then somersaulted in to
his head. Bet he couldn't do that again if he tried

Why would discs be more likely to release the wheel? This makes no
sense to me.

How technical do you want to get?
http://www.kinetics.org.uk/html/disc_brakes___qrs.html

Alex Bird wrote:

This is my first post to this group, sorry it's a bit grim.
I saw a tv programme 3-4 years ago here in the uk, about a kid in the
west-country (SW England). His front wheel came loose and _somehow_
the forks ended up in the back of his skull. They showed the x-rays,
a few more millimetres and he would have been dead. Yes, he was fine,
after some medical attention. I think I've checked my quick release
every time I've got on my bike since I saw that...

Not quite the same thing. He popped a wheelie off a kerb, the wheel
fell out, chucked him over the bars and the bike then somersaulted in to
his head. Bet he couldn't do that again if he tried

That was from 999, and was way longer than 3 or 4 years ago.

Why would discs be more likely to release the wheel? This makes no
sense to me.

How technical do you want to get?
http://www.ne.jp/asahi/julesandjames...quick_release/

Most likely more than half of the people out there that ride 'mountain
bikes' have never heard of this issue and wouldn't know where to find
a 'quick release skewer' on their bikes if they had to. Many of the
pure recreational riders and Dewbies that I know just aren't
interested in regular equipment checks. They'll check it if it
happens, otherwise ignorance is bliss and they'll ride it 'til it
breaks.

With so many amateur riders out there it's amazing that front wheels
aren't falling off left, right and centre. And not from braking
forces - just from lack of proper adjustment.

You really think so?
I get a bit paranoid about my QR skewers and check them before every ride.
I also check my headset before every ride, though that didn't stop it
getting loose on my last run.

I think it may be the way I ride - everything seems to come loose on my
bike. I've had the saddle come loose once too.

Last thing I want to be doing is eating my steering tube for breakfast...

--
....meandering mule...

bomba wrote in message ...
Doug Taylor wrote:

So, my question is: has anybody who actually rides mountain bike with
any frequency (such as the amb crowd) experienced this phenomenon or
heard of anybody loosing a wheel? If so, any serious injuries? Is
the sky really falling or can we get back on our bikes and ride?

Do you remember a guy posting here called Russ Pinder? Well, he's
currently in a wheelchair.

I believe that an analysis of the accident says the cause for the
wheel ejection was not knon, and might never be known. Without
knowing the initial conditions, nor having any analysis done on the
fork post-crash, I don't think anyone will ever know exactly how it
happened.

Spider

On Tue, 2 Sep 2003 11:09:56 +1200, Westie penned:


Any piece of equipment needs adjustment from time to time to keep it both
safe and well tuned.
But there are riders out there that just ride until something major falls
off - and if it's the QR coming loose because it hasn't been checked - ever,
then you've got a problem. I'm not saying that they're careless or
incompetant, it's just never something that occurs to them. They consider
the worst thing that can happen to them is a puncture or maybe 'changing
gear' problems. Maintenance is a bit of oil on the chain. It's never
occurred to them that a wheel might fall off.
--
Westie


I specifically asked a LBS about bike maintenance classes, and
the salesguy claimed that he knew of no such thing in the area. As my
fiance seems to have a handle on the maintenance thing, I haven't gone
looking too hard, but, jeez! The LBS guy acted like it should all be common
sense ... and maybe it should ... but I've never assembled or maintained
anything mechanical, aside from putting parts into a computer, where all
moving parts are carefully hidden from the user. I know enough to know
that I don't know what I'm doing when it comes to bikes (cars, lawn
mowers, garbage disposals, spigots ...).

At least mounting the bike on the car every trip means I have to make
sure my front tire is properly positioned before riding off ... and
after having an issue with my brakes at the beginning of one trip
(something about the end of the wire near the handlebars coming out of
position), I do test both front and rear brakes before going anywhere.

--
monique

I have had the QR open on my Cannondale F900 with disc brakes. The
lawyer tabs kept the wheel from coming all the way out and it was an
interesting ride feel until I got stopped. I was bombing some very washboard
single track at the time. It has only happened the one time. I am pretty
diligent about making sure that when put the front wheel on that I have it
tight, so I do not think that this was the problem. Who knows.
This has never happened on any of my other bikes, present or past that
have "regular" brakes.

Mike


"Doug Taylor" wrote in message
...
The boys (the girls are too sensible, it seems) in rec.bicycles.tech
are going at it once again on this subject, with the tech heads and
roadies basically saying that you are taking your life in your hands
if you use disc brakes with QR's and regular dropouts on the theory
that the QR eventually will come loose under force of the front brake
and your wheel will pop off.

So, my question is: has anybody who actually rides mountain bike with
any frequency (such as the amb crowd) experienced this phenomenon or
heard of anybody loosing a wheel? If so, any serious injuries? Is
the sky really falling or can we get back on our bikes and ride?

--dt

RE/
I switched to non-quick release skewers
about a month ago. I always considered quick release to be a solution to
a problem I never had. It's no big deal to carry an allen wrench and it
makes it tougher for a thief to steal your wheels. Don't have QR on my
seat collar either.

Where did you get them? I'd like to get a set just because the levers on mine
are so hard to open up when the wheel needs removing...
-----------------------
PeteCresswell

RE/
Why would discs be more likely to release the wheel?

Something about the direction of forces infolved when the calipers grab the
disk. I can't put it into words, but after reading the discussions here I can
visualize it easily. One clue: if the calipers were in front of the hub
instead of behind, there wouldn't be a problem.
-----------------------
PeteCresswell

RE/
With so many amateur riders out there it's amazing that front wheels aren't
falling off left, right and centre. And not from braking forces - just from
lack of proper adjustment.

I don't check mine either - but I think there's a fallacy in the "..we haven't
heard anything about it, so it must not be happening...." line of thinking.

Nobody's doing post-crash analysis' of bike accidents like the FAA does in
airplane crashes and people who get greviously injured probably don't broadcast
it to the world. More likely, they just sort of fade away from the biking
world...

Bottom line for me is that nobody really knows - qualified by the observation
that there hasn't yet been a legal feeding frenzy involving fork makers, which
has to count for something considering the litigiousness (sp?) of the current
release of USA.
-----------------------
PeteCresswell

(Pete Cresswell) said...

Where did you get them? I'd like to get a set just because the levers on mine
are so hard to open up when the wheel needs removing...
-----------------------
PeteCresswell

Nashbar. There is a category for skewers. They're nothing fancy, but
they get the job done. I don't miss QR at all.