Another scary crash video



On Jun 19, 10:05 pm, Michael Press <[email protected]> wrote:
> In article
> <[email protected]m>,
>
>
>
>  "[email protected]" <[email protected]> wrote:
> > On Jun 19, 7:26 am, [email protected] wrote:
> > > On Jun 19, 8:23 am, John Forrest Tomlinson <[email protected]>
> > > wrote:

>
> > > > Yeah. Perhaps rider error, perhaps oil. If I heard later his tire
> > > > flatted just then I wouldn't be surprised either.  But NOT severe
> > > > frame flex for those bikes specifically.

>
> > > not severe flex, but just enough under load- or something else about
> > > the frame- last year at the tdf there were a couple of occaisions
> > > where the csc rider was unable to negoiate the curve on a descent,
> > > whereas other riders did-  anyone re-watching the tdf2007 dvds might
> > > just take a note of the number of times a csc rider had trouble on a
> > > curve

>
> > Side load on a head tube, or just about any frame
> > part, during a descent is essentially zero.  Bicycles
> > lean into corners rather than scrubbing tires like cars.
> > I could see issues from either an ultra flexy fork or
> > flex in a really long steerer and headtube (which can
> > contribute to shimmy), but hardly any of these guys
> > ride such a frame.

>
> I do not think it is that simple.
> What you describe is true for a constant curvature turn.
> Descents require very hard changes in the
> bicycle's aspect. This puts forces every
> which way on the front of the bicycle.
>


I don't think it's that complicated. Although the bike lean
angle changes as you enter and exit turns, it does so
gradually. Turns are initiated by small amounts of
countersteer and your COG is more or less in plane
with the wheel. While descending, you never turn the
handlebars very far, even if you really have to slow
down to enter a turn. The majority of the force on the
headtube is not side load, but fore-aft from braking
force. There are exceptions, like if you are doing a
slow-speed technical MTB descent, but they're not
relevant to Schleck's Cervelo.

You can put a side load on the head tube while climbing
or sprinting when you lean the bike and pull on the
handlebars. When descending, you would rarely
put that kind of force on the handlebar. I think if you're
descending on the road and you manage to put a large
side load on the head tube, you're going to fall down,
and it has nothing to do with magical frame-flex
properties.

Ben
 
M

Michael Press

Guest
In article <[email protected]>,
John Forrest Tomlinson <[email protected]> wrote:

> On Sun, 22 Jun 2008 08:24:42 -0700 (PDT), Scott
> <[email protected]> wrote:
>
> >On Jun 22, 9:11 am, John Forrest Tomlinson <[email protected]>
> >wrote:
> >> On Sun, 22 Jun 2008 07:12:20 -0700 (PDT), Scott
> >>
> >> <[email protected]> wrote:
> >> >I've never spoken to another racer who understood
> >> >that a bicycle has a natural tendency to upright itself and go
> >> >straight when applying front brake forces.  Lot's of folks may do it
> >> >intuitively, but aside from the folks who've written the articles
> >> >which I've read on the matter, I haven't found anyone who was aware or
> >> >or understood the physics behind the phenomenon.
> >>
> >> So what?  Good riders know if they hit the braks the bike goes up, so
> >> they try not to do it mid-turn.  They dont' udnerstand the physics -
> >> so what?
> >>
> >> Well, I guess you're smarter and better read than most.  Congrats.

> >
> >Help me out here, why are you so argumentative this morning?

>
> People bragging about how they know stuff that others don't annoys me.
>
> >
> >FWIW, if you were to take a poll on your next group ride, I think
> >you'd be very surprised how few riders, or racers for that matter,
> >know anything at all about how trail is determined,

>
> Who cares? I don't. I know if I hit the brakes when leaned over hard
> in a corner I'll either slide out or the bike will jerk upright.
> That's enough. Good racers know that.


Does Schleck know that? Or did Schleck spill for some
reason other than what Scott says?

--
Michael Press
 
J

John Forrest Tomlinson

Guest
On Sun, 22 Jun 2008 23:55:44 -0700, Michael Press <[email protected]>
wrote:

>In article <[email protected]>,
> John Forrest Tomlinson <[email protected]> wrote:
>
>> On Sun, 22 Jun 2008 08:24:42 -0700 (PDT), Scott
>> <[email protected]> wrote:
>>
>> >On Jun 22, 9:11 am, John Forrest Tomlinson <[email protected]>
>> >wrote:
>> >> On Sun, 22 Jun 2008 07:12:20 -0700 (PDT), Scott
>> >>
>> >> <[email protected]> wrote:
>> >> >I've never spoken to another racer who understood
>> >> >that a bicycle has a natural tendency to upright itself and go
>> >> >straight when applying front brake forces.  Lot's of folks may do it
>> >> >intuitively, but aside from the folks who've written the articles
>> >> >which I've read on the matter, I haven't found anyone who was aware or
>> >> >or understood the physics behind the phenomenon.
>> >>
>> >> So what?  Good riders know if they hit the braks the bike goes up, so
>> >> they try not to do it mid-turn.  They dont' udnerstand the physics -
>> >> so what?
>> >>
>> >> Well, I guess you're smarter and better read than most.  Congrats.
>> >
>> >Help me out here, why are you so argumentative this morning?

>>
>> People bragging about how they know stuff that others don't annoys me.
>>
>> >
>> >FWIW, if you were to take a poll on your next group ride, I think
>> >you'd be very surprised how few riders, or racers for that matter,
>> >know anything at all about how trail is determined,

>>
>> Who cares? I don't. I know if I hit the brakes when leaned over hard
>> in a corner I'll either slide out or the bike will jerk upright.
>> That's enough. Good racers know that.

>
>Does Schleck know that? Or did Schleck spill for some
>reason other than what Scott says?


You're playing both sides. On the one hand you say you're not
bragging, you're only saying you're one of the few people who
understand on a conceptual or theoretical level the problem.

And on the other hand there's youre comment above, which suggests mor
than that.

And yes, Schleck knows that. Doesn't mean he can't make a mistake.
 
D

Donald Munro

Guest
Paul G. wrote:
> Yes, that's a bold statement but where are the equations to support it?
> Every competent racer of Category 1 and most of the Cat 2's can do the
> math in their heads, real time. The leaning equation is:
> http://tinyurl.com/5rpp6k
>
> and the steering equation is:
> http://tinyurl.com/3wr9mf
>
> where
>
> * θr is the lean angle of the rear assembly, * ψ is the steer angle
> of the front assembly relative to the rear
> assembly and
> * Mθ and Mψ are the moments (torques) applied at the rear assembly
> and the steering axis, respectively.
>
> Most of the rider-error crashes in turns you see in pro races are due to
> poor math skills.


Dumbass,
Why do you have a bike computer if you can't use it to do the math for
you ? My computer can even generate a naked view simulation of the hot
chick in front of me's ass.
 
S

Scott

Guest
On Jun 23, 3:18 am, John Forrest Tomlinson <[email protected]>
wrote:
> On Sun, 22 Jun 2008 23:55:44 -0700, Michael Press <[email protected]>
> wrote:
>
>
>
>
>
> >In article <[email protected]>,
> > John Forrest Tomlinson <[email protected]> wrote:

>
> >> On Sun, 22 Jun 2008 08:24:42 -0700 (PDT), Scott
> >> <[email protected]> wrote:

>
> >> >On Jun 22, 9:11 am, John Forrest Tomlinson <[email protected]>
> >> >wrote:
> >> >> On Sun, 22 Jun 2008 07:12:20 -0700 (PDT), Scott

>
> >> >> <[email protected]> wrote:
> >> >> >I've never spoken to another racer who understood
> >> >> >that a bicycle has a natural tendency to upright itself and go
> >> >> >straight when applying front brake forces.  Lot's of folks may do it
> >> >> >intuitively, but aside from the folks who've written the articles
> >> >> >which I've read on the matter, I haven't found anyone who was aware or
> >> >> >or understood the physics behind the phenomenon.

>
> >> >> So what?  Good riders know if they hit the braks the bike goes up, so
> >> >> they try not to do it mid-turn.  They dont' udnerstand the physics -
> >> >> so what?

>
> >> >> Well, I guess you're smarter and better read than most.  Congrats..

>
> >> >Help me out here, why are you so argumentative this morning?

>
> >> People bragging about how they know stuff that others don't annoys me.

>
> >> >FWIW, if you were to take a poll on your next group ride, I think
> >> >you'd be very surprised how few riders, or racers for that matter,
> >> >know anything at all about how trail is determined,

>
> >> Who cares? I don't. I know if I hit the brakes when leaned over hard
> >> in a corner I'll either slide out or the bike will jerk upright.
> >> That's enough.  Good racers know that.

>
> >Does Schleck know that? Or did Schleck spill for some
> >reason other than what Scott says?

>
> You're playing both sides.  On the one hand you say you're not
> bragging, you're only saying you're one of the few people who
> understand on a conceptual or theoretical level the problem.
>
> And on the other hand there's youre comment above, which suggests mor
> than that.
>
> And yes, Schleck knows that.  Doesn't mean he can't make a mistake.- Hide quoted text -
>
> - Show quoted text -


Merely stating that I've never spoken with anyone who was aware of the
WHY behind a bike behaving the way it does when you apply the front
brake while turning is not in any way bragging. If I'd called you a
dumbass first, then maybe. But I didn't. I merely stated the fact
that of all the people I've spoken with (not many, mind you...
steering geometry and braking while turning rarely comes up in polite
conversation) none were aware that the steering geometry of the bike
influenced it's behaviour while braking or that the solution is to
apply more down-force on the inside bar before starting to brake.

And, how can you be so sure that Schleck knows anything at all about
trail and braking? He might, but then again, he might not.
 
P

Paul G.

Guest
On Jun 23, 2:24 am, Donald Munro <[email protected]> wrote:
> Paul G. wrote:
> > Yes, that's a bold statement but where are the equations to support it?
> > Every competent racer of Category 1 and most of the Cat 2's can do the
> > math in their heads, real time. The leaning equation is:
> >http://tinyurl.com/5rpp6k

>
> > and the steering equation is:
> >http://tinyurl.com/3wr9mf

>
> > where

>
> >     * èr is the lean angle of the rear assembly, * ø is the steer angle
> >     of the front assembly relative to the rear
> > assembly and
> >     * Mè and Mø are the moments (torques) applied at the rear assembly
> > and the steering axis, respectively.

>
> > Most of the rider-error crashes in turns you see in pro races are due to
> > poor math skills.

>
> Dumbass,
> Why do you have a bike computer if you can't use it to do the math for
> you ? My computer can even generate a naked view simulation of the hot
> chick in front of me's ass.


( | )

Oh yeah... and she's wearing red Silca pumps, right?
-Paul
 
P

Paul G.

Guest
On Jun 23, 7:07 am, Scott <[email protected]> wrote:
> On Jun 23, 3:18 am, John Forrest Tomlinson <[email protected]>
> wrote:
>
>
>
> > On Sun, 22 Jun 2008 23:55:44 -0700, Michael Press <[email protected]>
> > wrote:

>
> > >In article <[email protected]>,
> > > John Forrest Tomlinson <[email protected]> wrote:

>
> > >> On Sun, 22 Jun 2008 08:24:42 -0700 (PDT), Scott
> > >> <[email protected]> wrote:

>
> > >> >On Jun 22, 9:11 am, John Forrest Tomlinson <[email protected]>
> > >> >wrote:
> > >> >> On Sun, 22 Jun 2008 07:12:20 -0700 (PDT), Scott

>
> > >> >> <[email protected]> wrote:
> > >> >> >I've never spoken to another racer who understood
> > >> >> >that a bicycle has a natural tendency to upright itself and go
> > >> >> >straight when applying front brake forces.  Lot's of folks maydo it
> > >> >> >intuitively, but aside from the folks who've written the articles
> > >> >> >which I've read on the matter, I haven't found anyone who was aware or
> > >> >> >or understood the physics behind the phenomenon.

>
> > >> >> So what?  Good riders know if they hit the braks the bike goes up, so
> > >> >> they try not to do it mid-turn.  They dont' udnerstand the physics -
> > >> >> so what?

>
> > >> >> Well, I guess you're smarter and better read than most.  Congrats.

>
> > >> >Help me out here, why are you so argumentative this morning?

>
> > >> People bragging about how they know stuff that others don't annoys me.

>
> > >> >FWIW, if you were to take a poll on your next group ride, I think
> > >> >you'd be very surprised how few riders, or racers for that matter,
> > >> >know anything at all about how trail is determined,

>
> > >> Who cares? I don't. I know if I hit the brakes when leaned over hard
> > >> in a corner I'll either slide out or the bike will jerk upright.
> > >> That's enough.  Good racers know that.

>
> > >Does Schleck know that? Or did Schleck spill for some
> > >reason other than what Scott says?

>
> > You're playing both sides.  On the one hand you say you're not
> > bragging, you're only saying you're one of the few people who
> > understand on a conceptual or theoretical level the problem.

>
> > And on the other hand there's youre comment above, which suggests mor
> > than that.

>
> > And yes, Schleck knows that.  Doesn't mean he can't make a mistake.- Hide quoted text -

>
> > - Show quoted text -

>
> Merely stating that I've never spoken with anyone who was aware of the
> WHY behind a bike behaving the way it does when you apply the front
> brake while turning is not in any way bragging.  If I'd called you a
> dumbass first, then maybe.  But I didn't.  I merely stated the fact
> that of all the people I've spoken with (not many, mind you...
> steering geometry and braking while turning rarely comes up in polite
> conversation) none were aware that the steering geometry of the bike
> influenced it's behaviour while braking or that the solution is to
> apply more down-force on the inside bar before starting to brake.
>
> And, how can you be so sure that Schleck knows anything at all about
> trail and braking?  He might, but then again, he might not.


I've been braking thru corners for many years. When I do, I'm using
both brakes and therefore gripping my bars. The bike does exactly what
I want it to do, (the technical term for this is "bike handling") and
I don't have to think about it. If it suddenly "uprighted itself" when
I braked while cornering I'd have been killed long ago.

So what you're saying has no relevance to my cycling experience. I'm
going to automatically do whatever is necessary to cut a smooth arc
thru the turn. I'm not going to be thinking about "putting a bit more
force into the inside handlebar", I'm strictly focused on cutting that
arc, hitting the apex of the turn, and if I'm lucky and Munro isn't
blocking the view, the ass on that hot chick.
-Paul