Can Disk Brakes flip you over the handle bars?

TBerk

Obviously I would assume they could if you clamp down fast enough.

I ask because I bruised some rib bones this week when I stomped the
front brake and *surprise* I found out later my front rim has a bubble
bend in it from (I guess) a pot hole at some recent time.

Made for a portion of the rim that just wasn't going to get past the
brake pads, not while I was trying to actually use said brakes.

It would seem a better setup would be one unaffected by a slightly
bent rim, or so I wonder.


TBerk
it would have been funny if it hadn't hurt so much at the time

jobst.brandt@stanfordalumni.org

The Berk wrote:

> Obviously I would assume they could if you clamp down fast enough.

> I ask because I bruised some rib bones this week when I stomped the
> front brake and *surprise* I found out later my front rim has a
> bubble bend in it from (I guess) a pot hole at some recent time.

> Made for a portion of the rim that just wasn't going to get past the
> brake pads, not while I was trying to actually use said brakes.

> It would seem a better setup would be one unaffected by a slightly
> bent rim, or so I wonder.

http://www.sheldonbrown.com/brandt/over-the-bars.html

> it would have been funny if it hadn't hurt so much at the time

Don't laugh. I wouldn't be so ready to tell all that I used bicycle
brakes in such a clumsy manner. Skilled motorcyclists do nose-down
wheelies at high speed, often crossing the finish line on only the
front wheel. That takes a bit of extra skill. A motorcyclist crashed
fatally yesterday in East Palo Alto doing that.

Jobst Brandt

mike.a.schwab@gmail.com

On Apr 30, 10:49 pm, TBerk <bayareab...@yahoo.com> wrote:
> Obviously I would assume they could if you clamp down fast enough.
>
> I ask because I bruised some rib bones this week when I stomped the
> front brake and *surprise* I found out later my front rim has a bubble
> bend in it from (I guess) a pot hole at some recent time.
>
> Made for a portion of the rim that just wasn't going to get past the
> brake pads, not while I was trying to actually use said brakes.
>
> It would seem a better setup would be one unaffected by a slightly
> bent rim, or so I wonder.
>
> TBerk
> it would have been funny if it hadn't hurt so much at the time

Disk brakes have more stopping power and any such 'stomp' can result
in a flip, not requiring any irregularities. Due to their design,
recumbents are immune from such a flip.

Harry Brogan

On Thu, 1 May 2008 01:33:03 -0700 (PDT), "mike.a.schwab@gmail.com"
<mike.a.schwab@gmail.com> wrote:

>On Apr 30, 10:49 pm, TBerk <bayareab...@yahoo.com> wrote:
>> Obviously I would assume they could if you clamp down fast enough.
>>
>> I ask because I bruised some rib bones this week when I stomped the
>> front brake and *surprise* I found out later my front rim has a bubble
>> bend in it from (I guess) a pot hole at some recent time.
>>
>> Made for a portion of the rim that just wasn't going to get past the
>> brake pads, not while I was trying to actually use said brakes.
>>
>> It would seem a better setup would be one unaffected by a slightly
>> bent rim, or so I wonder.
>>
>> TBerk
>> it would have been funny if it hadn't hurt so much at the time
>
>Disk brakes have more stopping power and any such 'stomp' can result
>in a flip, not requiring any irregularities. Due to their design,
>recumbents are immune from such a flip.

Perhaps the TWO wheel recumbents are immune. However, I have found
that, on my tadpole, if I jam the brakes HARD the rear wheel WILL lift
up. Fortunately I usually have enough weight back there to avoid a
total "flip". ((loaded saddlebags, flags, lightbar..etc))



__o | Every time I see an adult on a bicycle....
_`\(,_ | I no longer despair for the human race.
(_)/ (_) | ---H.G. Wells---

DougC

jobst.brandt@stanfordalumni.org wrote:
> The Berk wrote:
>
>> Obviously I would assume they could if you clamp down fast enough.
>
>> I ask because I bruised some rib bones this week when I stomped the
>> front brake and *surprise* I found out later my front rim has a
>> bubble bend in it from (I guess) a pot hole at some recent time.
>> ....
>
> http://www.sheldonbrown.com/brandt/over-the-bars.html
>
>> it would have been funny if it hadn't hurt so much at the time

As someone else noted, most recumbents are immune to this
flipping-over-forward problem under hard braking. In my opinion this is
another reason that recumbents may be safer for general use--in that
during a panic stop, the brakes can be applied with wild abandon and
while the bike may slide out and drop the rider sideways, at least it's
not going to flip them over onto their head.... Usually (with any type
of cable-operated brakes) neither wheel will lock up. The LWB recumbent
I have has 160mm BB5 (cable) disk brakes and can't lock either wheel on
clean pavement at all. The RANS Fusion I own isn't that much longer or
lower than a normal upright bicycle; it has 200mm BB7's and won't lock
up or flip over forward either, from a normal riding position, and that
bike basically only has one riding position (standing on the pedals
requires serious effort for anything more than a few moments, and the
pedals are so far forward of the seat that you cannot scoot backwards
off the seat at all). Both these bikes carry about 66% of the weight on
the rear tire normally; that may not be ideal for racing but it seems to
improve safety.

Of course you always get people who claim they can stop an upright bike
perfectly fine,,, but this sounds kinda like when anti-lock brakes first
became common on cars and some people argued that they "didn't need it".
....Which is true in the absolute, you don't /need/ it, but you can't
stop as quickly without it, or with as good of control. Over time the
advantages of not losing directional control in a panic stop became
pretty obvious in repeated studies, and if you brake hard enough to lift
the rear wheel of an upright bike off the ground, then you've pretty
much lost control.

Also if you enter the words {bicycle over bars crash} in Google, you get
back a huge number of results--you still see a lot of people telling
"over-the-bars" stories, which was what safety bikes were supposed to
solve compared to the earlier penny-farthings. If you enter the
words("recumbent bicycle" over bars crash} you get very few, and most of
those aren't discussing such a recumbent crash at all. Much of the
upright-bike results seem to be off-road/MTB stories however, which I
don't consider a "typical" riding situation in terms of safety. When
you're riding off-road you do all sorts of stupid stuff, it's what MTB's
are for. The flipping-forward problem I only consider to be important
with on-road use bicycles.

I don't know that this translates into shorter stopping distances
however. It'd be interesting to compare two bicycles with hydraulic disk
brakes (and speedometers)- an upright MTB and a LWB recumbent--and do a
three-way comparison to see which one can stop quickest from a given
speed. The recumbent, with the rider in the normal (only) riding
position, and the MTB in the normal riding position, and also the MTB
with the rider low, arms locked and scooted backwards off the saddle.

The reason I say "hydraulic brakes" is that the power of cable-operated
disks varies with the cable lengths. The braking power front-to-rear on
an upright bike is a bit disappointing, but the difference on a longer
recumbent can be huge (does anyplace make thicker brake cable & jacket,
that will work with normal brakes? I'd try it...). I'd love to see
results of this kind of testing, but can't be much help as I won't
likely be putting hydraulics on either of my bikes anytime soon.

.....If you *prepare* yourself for braking you can lay on the front brake
of an upright--but that is the exact problem; many people who suffer
these crashes during on-road use are unaware they will have to stop
until it's too late.

>
> Don't laugh. I wouldn't be so ready to tell all that I used bicycle
> brakes in such a clumsy manner. Skilled motorcyclists do nose-down
> wheelies at high speed, often crossing the finish line on only the
> front wheel. That takes a bit of extra skill. A motorcyclist crashed
> fatally yesterday in East Palo Alto doing that.
>

This is called a reverse wheelie, or a "stoppie":
http://www.dirtrodders.com/stoppie.html
Interesting on this page, that the article notes that the front brake
(of a motorcycle) needs to be applied smoothly, or else the front wheel
will simply slide. (I don't have a motorcycle, so I can't play these
sorts of games)
I am informed that it's bad for the fork seals.
There's classic photos on the stuntlife website of one kid attempting a
stoppie--likely not the first time--and his forks crumpling at the
triple clamps and the bike falling onto him (Stuntlife's motto seems to
be something like "Keeping high school overpopulation in check, one
motorcycle rider at a time").
~

Clive George

"DougC" <dcimper@norcom2000.com> wrote in message
news:6tiSj.813$sC6.2@newsfe07.lga...

> The reason I say "hydraulic brakes" is that the power of cable-operated
> disks varies with the cable lengths. The braking power front-to-rear on an
> upright bike is a bit disappointing, but the difference on a longer
> recumbent can be huge (does anyplace make thicker brake cable & jacket,
> that will work with normal brakes? I'd try it...).

It's why our tandems all have hydraulic brakes. 2 with magura rims, one with
discs.

And tandems also have the "brake as hard as you like, you're not going over
the top" thing :-)

cheers,
clive

landotter

On Apr 30, 10:49 pm, TBerk <bayareab...@yahoo.com> wrote:
> Obviously I would assume they could if you clamp down fast enough.

Yes, if you don't brace yourself and are unfamiliar with the brake and
grab wildly, any powerful brake can be dangerous--but so can many
things in life. Well adjusted brakes should be easy to modulate,
provided you're not inebriated and have practiced a few panic stops,
and shouldn't necessitate the purchase of a new bicycle.

Be careful when posting questions like this, because you may attract
'bent riders, who are bearded hammers in search of nails--sometimes
with orange flippy flags!

TBerk

On Apr 30, 9:48 pm, jobst.bra...@stanfordalumni.org wrote:
> The Berk wrote:
> > Obviously I would assume they could if you clamp down fast enough.
> > I ask because I bruised some rib bones this week when I stomped the
> > front brake and *surprise* I found out later my front rim has a
> > bubble bend in it from (I guess) a pot hole at some recent time.
> > Made for a portion of the rim that just wasn't going to get past the
> > brake pads, not while I was trying to actually use said brakes.
> > It would seem a better setup would be one unaffected by a slightly
> > bent rim, or so I wonder.
>
> http://www.sheldonbrown.com/brandt/over-the-bars.html
>
> > it would have been funny if it hadn't hurt so much at the time
>
> Don't laugh. I wouldn't be so ready to tell all that I used bicycle
> brakes in such a clumsy manner. Skilled motorcyclists do nose-down
> wheelies at high speed, often crossing the finish line on only the
> front wheel. That takes a bit of extra skill. A motorcyclist crashed
> fatally yesterday in East Palo Alto doing that.
>
> Jobst Brandt


Bite me Jobst.

TBerk

TBerk

On May 1, 6:47 am, landotter <landot...@gmail.com> wrote:
> On Apr 30, 10:49 pm, TBerk <bayareab...@yahoo.com> wrote:
>
> > Obviously I would assume they could if you clamp down fast enough.
>
> Yes, if you don't brace yourself and are unfamiliar with the brake and
> grab wildly, any powerful brake can be dangerous--but so can many
> things in life. Well adjusted brakes should be easy to modulate,
> provided you're not inebriated and have practiced a few panic stops,
> and shouldn't necessitate the purchase of a new bicycle.
>
> Be careful when posting questions like this, because you may attract
> 'bent riders, who are bearded hammers in search of nails--sometimes
> with orange flippy flags!



Yeah, I have a feeling a got one of them on the line right now.

Folks, obviously if I had known the rim had a problem I would have
factored that in, either readjusting the brakes, massaging the rim,
drove around instead of stopping suddenly,and/or all of the above.

TBerk

jobst.brandt@stanfordalumni.org

Doug Cimper wrote:

>>> Obviously I would assume they could if you clamp down fast enough.

>>> I ask because I bruised some rib bones this week when I stomped the
>>> front brake and *surprise* I found out later my front rim has a
>>> bubble bend in it from (I guess) a pot hole at some recent time.
>>> ....

http://www.sheldonbrown.com/brandt/over-the-bars.html

>>> it would have been funny if it hadn't hurt so much at the time

>> Don't laugh. I wouldn't be so ready to tell all that I used
>> bicycle brakes in such a clumsy manner. Skilled motorcyclists do
>> nose-down wheelies at high speed, often crossing the finish line on
>> only the front wheel. That takes a bit of extra skill. A
>> motorcyclist crashed fatally yesterday in East Palo Alto doing
>> that.

> As someone else noted, most recumbents are immune to this
> flipping-over-forward problem under hard braking. In my opinion
> this is another reason that recumbents may be safer for general
> use--in that during a panic stop, the brakes can be applied with
> wild abandon and while the bike may slide out and drop the rider
> sideways, at least it's not going to flip them over onto their
> head...

I think you should read the FAQ item first at:

http://www.sheldonbrown.com/brandt/over-the-bars.html

before giving the usual endless pitch about the superiority of
recumbents. Going over the bars, especially with disk brakes, is
highly unlikely to be caused by locking the front wheel, but rather
follows the scenario described in the FAQ.

Jobst Brandt

Jay Beattie

On May 1, 6:47*am, landotter <landot...@gmail.com> wrote:
> On Apr 30, 10:49 pm, TBerk <bayareab...@yahoo.com> wrote:
>
> > Obviously I would assume they could if you clamp down fast enough.
>
> Yes, if you don't brace yourself and are unfamiliar with the brake and
> grab wildly, any powerful brake can be dangerous--but so can many
> things in life. Well adjusted brakes should be easy to modulate,
> provided you're not inebriated and have practiced a few panic stops,
> and shouldn't necessitate the purchase of a new bicycle.
>
> Be careful when posting questions like this, because you may attract
> 'bent riders, who are bearded hammers in search of nails--sometimes
> with orange flippy flags!

Oooooh. You're gonna get it now! Those recumbent guys are mean --
head for the hills. Really -- and don't wait at the top.

For the OP: Properly adjusted mechanical discs are no more likely to
put you over the bars than properly adjusted dual-pivots with good
pads and straight rims. They have a different feel and they perform
far better in wet weather, but they are not scary strong -- at least
not the ones on my cross/commuter bike. Discs oviously are immune to
rim problems, but they have their own set of potential problems
including wharped rotors, bent pad clips, etc., etc. Like everyone
said, any good brake can launch you in a panic stop if you are not
properly positioned. -- Jay Beattie.

jobst.brandt@stanfordalumni.org

The Berk wrote:

>>> Obviously I would assume they could if you clamp down fast enough.

>> Yes, if you don't brace yourself and are unfamiliar with the brake and
>> grab wildly, any powerful brake can be dangerous--but so can many
>> things in life. Well adjusted brakes should be easy to modulate,
>> provided you're not inebriated and have practiced a few panic stops,
>> and shouldn't necessitate the purchase of a new bicycle.

>> Be careful when posting questions like this, because you may attract
>> 'bent riders, who are bearded hammers in search of nails--sometimes
>> with orange flippy flags!

> Yeah, I have a feeling a got one of them on the line right now.

> Folks, obviously if I had known the rim had a problem I would have
> factored that in, either readjusting the brakes, massaging the rim,
> drove around instead of stopping suddenly,and/or all of the above.

Wait a minute. You started this thread with the heading about "disk
brakes". How about getting the description consistent with the story.
Besides, unless a rim is offset so there is a significant step in the
alignment before and after a break, a ding in a rim will also not
cause the front wheel to lock.

You "went over the bars" in the usual manner and leave it at that.

Jobst Brandt

frkrygow@gmail.com

On May 1, 11:39 am, TBerk <bayareab...@yahoo.com> wrote:
>
>
> Folks, obviously if I had known the rim had a problem I would have
> factored that in, either readjusting the brakes, massaging the rim,
> drove around instead of stopping suddenly,and/or all of the above.

I'm surprised this happened to you, for several reasons.

One is, a minor ding in a rim should be noticeable the first time you
gently touch the brakes, maybe even sooner. If that happened,
wouldn't you know not to jam the brakes on hard?

A second is, hard braking should be a very rare occurrence, unless
perhaps you ride down lots of truly extreme hills. If there were room
to ride around whatever it was, wouldn't you do that instead of panic
braking?

I suppose it's possible that you had a really major ding in the rim,
and it occurred immediately before you hit the brakes, so your first
brake application was the one that threw you. But that seems
unlikely.

BTW, I don't think that readjusting the brakes would help. No matter
how much rim clearance they have when released, they're going to have
zero rim clearance when you apply them.

Disk brakes have their own problems. Rather than contemplating a
switch, I think it's better to learn to care for your bike, and pay
attention to the road. And I'm not trying to sound harsh. That's
just the way it is.

- Frank Krygowski

Michael Press

In article
<3d81ffd1-3ac3-4758-a96c-27a116cd271b@n1g2000prb.googlegroups.com>,
TBerk <bayareaberk@yahoo.com> wrote:

> On Apr 30, 9:48 pm, jobst.bra...@stanfordalumni.org wrote:
> > The Berk wrote:
> > > Obviously I would assume they could if you clamp down fast enough.
> > > I ask because I bruised some rib bones this week when I stomped the
> > > front brake and *surprise* I found out later my front rim has a
> > > bubble bend in it from (I guess) a pot hole at some recent time.
> > > Made for a portion of the rim that just wasn't going to get past the
> > > brake pads, not while I was trying to actually use said brakes.
> > > It would seem a better setup would be one unaffected by a slightly
> > > bent rim, or so I wonder.
> >
> > http://www.sheldonbrown.com/brandt/over-the-bars.html
> >
> > > it would have been funny if it hadn't hurt so much at the time
> >
> > Don't laugh. I wouldn't be so ready to tell all that I used bicycle
> > brakes in such a clumsy manner. Skilled motorcyclists do nose-down
> > wheelies at high speed, often crossing the finish line on only the
> > front wheel. That takes a bit of extra skill. A motorcyclist crashed
> > fatally yesterday in East Palo Alto doing that.
> >
> > Jobst Brandt
>
>
> Bite me Jobst.
>

TBerk, have you ever gone over your bars while braking?

--
Michael Press