Re: Great drafting

[gds]

On May 23, 11:55 am, Diablo Scott > wrote:
> gds wrote:
> > At 30 mph
> > these trucks can stop a lot faster than you can on your bike.
>
> No they can't. Reaction time is an issue but not stopping distance.
>
> Best drafting ever: a roofing truck, thing must have been 15 feet high
> and sat low to the ground ... I was coasting at 40mph.

What is your point?
My point is that if you are drafting closely to a big truck at 30 mph
and they brake hard without warning you have a good chance of running
into it. Stopping involves both reaction time and stopping distance
once braking is activated. Parsing out how much of the issue is
reaction time vs. the physical act of stopping doesn't seem the
important issue.

[Diablo Scott]

gds wrote:
> On May 23, 11:55 am, Diablo Scott > wrote:
>> gds wrote:
>>> At 30 mph
>>> these trucks can stop a lot faster than you can on your bike.
>> No they can't. Reaction time is an issue but not stopping distance.
>>
>> Best drafting ever: a roofing truck, thing must have been 15 feet high
>> and sat low to the ground ... I was coasting at 40mph.
>
> What is your point?
> My point is that if you are drafting closely to a big truck at 30 mph
> and they brake hard without warning you have a good chance of running
> into it. Stopping involves both reaction time and stopping distance
> once braking is activated. Parsing out how much of the issue is
> reaction time vs. the physical act of stopping doesn't seem the
> important issue.
>

My point was that your original statement was misleading; a bike can
decelerate at a higher rate than a big truck.

What this means is that any particular rider can draft a massive truck
more closely than he can draft a smaller vehicle, with the same factor
of safety.

This post is not intended to promote dangerous riding of course.

[gds]

On May 23, 1:02 pm, Diablo Scott > wrote:
> gds wrote:
> > On May 23, 11:55 am, Diablo Scott > wrote:
> >> gds wrote:
> >>> At 30 mph
> >>> these trucks can stop a lot faster than you can on your bike.
> >> No they can't. Reaction time is an issue but not stopping distance.
>
> >> Best drafting ever: a roofing truck, thing must have been 15 feet high
> >> and sat low to the ground ... I was coasting at 40mph.
>
> > What is your point?
> > My point is that if you are drafting closely to a big truck at 30 mph
> > and they brake hard without warning you have a good chance of running
> > into it. Stopping involves both reaction time and stopping distance
> > once braking is activated. Parsing out how much of the issue is
> > reaction time vs. the physical act of stopping doesn't seem the
> > important issue.
>
> My point was that your original statement was misleading; a bike can
> decelerate at a higher rate than a big truck.
>
> What this means is that any particular rider can draft a massive truck
> more closely than he can draft a smaller vehicle, with the same factor
> of safety.
>
> This post is not intended to promote dangerous riding of course.- Hide quoted text -
>
> - Show quoted text -

And my original point was to make sure that the truck driver knows
what you are doing and agrees to it. Then you shouldn't have to worry
(asmuch)about sudden braking.
As a matter of practice driver/rider cooperation is the key variable.
Look at motor pacing with a motorcycle as part of training for speed.
The motorcycle is much closer in size and weight to the bicycle than
(almost) and car or truck. Yet the bicyclist will ride right up on the
motorcycle. In fact once they have gotten speeds equalized the
bicyclist will actually be able to bump his front wheel with the
motorcyclist's rear wheel. Since they are turning at the same speed
this works out OK. And since the motorcycle driver is a partner in the
process and will drive in a manner consistent with the bicyclist's
safety the event is prettty safe.

[Leo Lichtman]

"gds" clip) In fact once they have gotten speeds equalized the bicyclist
will actually be able to bump his front wheel with the motorcyclist's rear
wheel. Since they are turning at the same speed this works out OK. (clip)
^^^^^^^^^^^^^^^^^
Where did you get that??? The rear of the motorcyclists tire is moving
UPWARD. The front of the bicyclists tire is moving DOWNWARD. If they
touch, the bicycle will be lifted upward.

[Leo Lichtman]

"gds" wrote: And my original point was to make sure that the truck driver
knows what you are doing and agrees to it. Then you shouldn't have to worry
(asmuch)about sudden braking. (clip)
^^^^^^^^^^^^^^^^^
There is a well-known rule, often posted on the backs of big trucks: "If
you can't see me in my mirrors, I can't see you." If you are drafting a van
or semi, chances you will be following too close, according to the above
rule.

[gds]

On May 23, 7:39 pm, "Leo Lichtman" >
wrote:
> "gds" clip) In fact once they have gotten speeds equalized the bicyclist
> will actually be able to bump his front wheel with the motorcyclist's rear
> wheel. Since they are turning at the same speed this works out OK. (clip)
> ^^^^^^^^^^^^^^^^^
> Where did you get that??? The rear of the motorcyclists tire is moving
> UPWARD. The front of the bicyclists tire is moving DOWNWARD. If they
> touch, the bicycle will be lifted upward.

I won't argue the physics. However, it is done all of the time. In
practice the bike is not lifted up, you simply bump and fall back a
small bit.I am not suggesting the bike tries to STAY in contact, just
a bump. I know it works because I've done it (successfully). My
earlier statement regarding theat it works becasue the wheels are
turning at the same speed is probably not the reason it works since as
you point out the contact is in different directions, so it is
probably that the two vehicles are at (nearly) the same speed and the
contact is short that this works OK.

[gds]

On May 23, 7:44 pm, "Leo Lichtman" >
wrote:
> "gds" wrote: And my original point was to make sure that the truck driver
>
> knows what you are doing and agrees to it. Then you shouldn't have to worry
> (asmuch)about sudden braking. (clip)
> ^^^^^^^^^^^^^^^^^
> There is a well-known rule, often posted on the backs of big trucks: "If
> you can't see me in my mirrors, I can't see you." If you are drafting a van
> or semi, chances you will be following too close, according to the above
> rule.
I agree! That is is accordane with my point that successfull drafting
of a motor vehicle implies a cooperative effort. The exception to yor
point "may" be when a coperting driver knows that a cyclist is
drafting closely and agrees to not brake for a given period of time or
to give a warning signal before braking.