Look Ma! No hands!

Quoted message said:

carrying about 8kJ of kinetic energy,

While I agree wholeheartedly about the sentiment, how on earth did you
get 8kJ of energy? By my count, 20mph is roughly 8.9 m/s, and 15 stone
is roughly 95 kg... which means the bike would have to weigh another 15
stone or so to get 8kJ!

Brian said:

Quoted message said:

carrying about 8kJ of kinetic energy,

While I agree wholeheartedly about the sentiment, how on earth did you
get 8kJ of energy? By my count, 20mph is roughly 8.9 m/s, and 15 stone
is roughly 95 kg... which means the bike would have to weigh another 15
stone or so to get 8kJ!

They were about 4.55m above the ground? (If my GPE calculations were
correct)

-Alex

Paul Weaver said:

To the 7 cyclists I passed this morning riding through hyde park, who
seem to think brakes and steering are for wimps:

It might have been cute when you were ten and riding in a field, but
when you are 15 stones, hurtling down a shared use path at 15-20mph,
carrying about 8kJ of kinetic energy, and have no brakes or steering to
avoid dogs and children, as well as ignoring other pedestrians and
cyclists who are forced to scatter out of your irratic course in your
arrogant quest, it's not "cool".

Yet despite the problems lots of folk seem to not only get around Dutch
towns without bothering too much about the handlebars, but they seem to
be able to conduct conversations on their mobile phones at the same time
with no consequent carnage...

While not wanting to suggest that no-hands is a Good Idea, it's not
nearly as fraught with collateral damage as some might assume. Did any
of the 7 above crash into anything or anyone? Were they /really/
erratic (no-hands can be steered with leaning, but is typically quite a
straight-ahead operation, almost always straight ahead at 15+ mph)?

And unicycles /are/ cool, actually!

Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net [email hidden] http://www.dundee.ac.uk/~pjclinch/

Peter Clinch said:

And unicycles /are/ cool, actually!

What about a recumbent unicycle?

The following has some other wierd and wonderful contraptions...

http://www.geocities.com/rcgilmore3/ExtremeBikes.htm

-Alex

Alex said:

The following has some other wierd and wonderful contraptions...

http://www.geocities.com/rcgilmore3/ExtremeBikes.htm

The Unipsycho looks like a "concept machine" Cannondale took to a show a
few years back for fun. I think even for those that Know What They're
Doing (that doesn't apply to me), clipless pedals are generally felt to
be Not A Cunning Plan on unis...

The Schlumpf geared unicycle is a wondrous thing, even though I wasn't
good enough to change gear on the move when I tried it. If^H^HWhen I
win the lottery or my Premium Bonds come up I will spend the £700 or so
and have my own.

Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net [email hidden] http://www.dundee.ac.uk/~pjclinch/

Brian said:

Quoted message said:

carrying about 8kJ of kinetic energy,

While I agree wholeheartedly about the sentiment, how on earth did you
get 8kJ of energy? By my count, 20mph is roughly 8.9 m/s, and 15 stone
is roughly 95 kg... which means the bike would have to weigh another 15
stone or so to get 8kJ!

Havey rucksack 🙂?

(Forgot the half in 1/2mv^2). I blame the coffee.

Peter Clinch said:

And unicycles /are/ cool, actually!

Yeah, if you're Krusty the Clown! I Just spent the weekend learning
to ride one, and my right ankle-bone is bruised to shtie, a curse on
the inventor of the poxy yokes!

Alex said:

They were about 4.55m above the ground? (If my GPE calculations were
correct)

That would be potential energy, not kinetic energy.

OK, it's potentially kinetic energy ...

-dan

--
http://coruskate.blogspot.com/ why skate when you can talk about it instead?

Paul Weaver wrote on 02/08/2006 09:58 +0100:

Quoted message said:

It might have been cute when you were ten and riding in a field, but
when you are 15 stones, hurtling down a shared use path at 15-20mph,
carrying about 8kJ of kinetic energy, and have no brakes or steering to
avoid dogs and children, as well as ignoring other pedestrians and
cyclists who are forced to scatter out of your irratic course in your
arrogant quest, it's not "cool".

Wow, 8kJ of energy. Enough to boil half a cup of water!

--
Tony

"Anyone who conducts an argument by appealing to authority is not using
his intelligence; he is just using his memory."
- Leonardo da Vinci

Tony Raven said:

Paul Weaver wrote on 02/08/2006 09:58 +0100:

Quoted message said:

It might have been cute when you were ten and riding in a field, but
when you are 15 stones, hurtling down a shared use path at 15-20mph,
carrying about 8kJ of kinetic energy, and have no brakes or steering to
avoid dogs and children, as well as ignoring other pedestrians and
cyclists who are forced to scatter out of your irratic course in your
arrogant quest, it's not "cool".

Wow, 8kJ of energy. Enough to boil half a cup of water!

It takes 400J to fracture a skull, less to fracture ribs. While in a
collision we can hope that the errant cyclist will take the full force
and die, preferably slowly and painfully, sadly it's likely the child
he (or at that height the solid inflexible bike) plows into will be the
one sustaining the most damage.

Peter Clinch said:

While not wanting to suggest that no-hands is a Good Idea, it's not
nearly as fraught with collateral damage as some might assume. Did any
of the 7 above crash into anything or anyone? Were they /really/
erratic (no-hands can be steered with leaning, but is typically quite a
straight-ahead operation, almost always straight ahead at 15+ mph)?

Yesterday afternoon was a close call, fortunatly an aware parent
snatched their child out of the way of a no-handed cyclist (in the
process of moving his hands to the bars) as he uncontrolably drifted
onto the pedestrian side of the path.

Paul Weaver wrote on 02/08/2006 11:22 +0100:

Quoted message said:

It takes 400J to fracture a skull, less to fracture ribs. While in a
collision we can hope that the errant cyclist will take the full force
and die, preferably slowly and painfully, sadly it's likely the child
he (or at that height the solid inflexible bike) plows into will be the
one sustaining the most damage.

700-1000J actually and all that energy has to be applied to the skull.
Gurdjian, E.S., Webster, J.E. and Lissner, H.R., "Studies on skull
fracture with particular reference to engineering factors" Am. J. Surg.
78(5), 736-742 (1949)

--
Tony

"Anyone who conducts an argument by appealing to authority is not using
his intelligence; he is just using his memory."
- Leonardo da Vinci

sothach said:

Peter Clinch said:

And unicycles /are/ cool, actually!

Yeah, if you're Krusty the Clown! I Just spent the weekend learning
to ride one, and my right ankle-bone is bruised to shtie, a curse on
the inventor of the poxy yokes!

Ankles are self-repairing (within limits). You'll feel differently in a
few weeks. :-)

--
Dave...

in message <[email hidden]>, Paul

Weaver (') said:

To the 7 cyclists I passed this morning riding through hyde park, who
seem to think brakes and steering are for wimps:

It might have been cute when you were ten and riding in a field, but
when you are 15 stones, hurtling down a shared use path at 15-20mph,
carrying about 8kJ of kinetic energy, and have no brakes or steering to
avoid dogs and children, as well as ignoring other pedestrians and
cyclists who are forced to scatter out of your irratic course in your
arrogant quest, it's not "cool".

Oh, get a grip. If you're anything like a reasonable cyclist you're every
bit as in control of your bike no hands as with your hands on the bars,
and getting you hands onto the bars in order to brake is a matter of a
moment.

--
[email hidden] (Simon Brooke) http://www.jasmine.org.uk/~simon/
;; Our modern industrial economy takes a mountain covered with trees,
;; lakes, running streams and transforms it into a mountain of junk,
;; garbage, slime pits, and debris. -- Edward Abbey

Tony Raven said:

Paul Weaver wrote on 02/08/2006 11:22 +0100:

Quoted message said:

It takes 400J to fracture a skull, less to fracture ribs. While in a
collision we can hope that the errant cyclist will take the full force
and die, preferably slowly and painfully, sadly it's likely the child
he (or at that height the solid inflexible bike) plows into will be the
one sustaining the most damage.

700-1000J actually and all that energy has to be applied to the skull.
Gurdjian, E.S., Webster, J.E. and Lissner, H.R., "Studies on skull
fracture with particular reference to engineering factors" Am. J. Surg.
78(5), 736-742 (1949)

Is that for an adult skull?

How much to fracture the skulls of children?

--
Don Whybrow

Sequi Bonum Non Time

"Question with boldness even the existence of a god; because, if
there be one, he must more approve of the homage of reason, than
that of blindfolded fear." - Thomas Jefferson

Simon Brooke said:

Oh, get a grip. If you're anything like a reasonable cyclist you're every
bit as in control of your bike no hands as with your hands on the bars

Well, up to a point, Lord Copper, but the slaient point is it's
good /enough/ that the Daily Mail isn't conducting a Hate campaign
against these awful no-hands cyclists. Which means it /is/ pretty
safe! ;-/

Pete.
--
Peter Clinch Medical Physics IT Officer
Tel 44 1382 660111 ext. 33637 Univ. of Dundee, Ninewells Hospital
Fax 44 1382 640177 Dundee DD1 9SY Scotland UK
net [email hidden] http://www.dundee.ac.uk/~pjclinch/

Simon Brooke said:

in message <[email hidden]>, Paul

Weaver (') said:

To the 7 cyclists I passed this morning riding through hyde park, who
seem to think brakes and steering are for wimps:

It might have been cute when you were ten and riding in a field, but
when you are 15 stones, hurtling down a shared use path at 15-20mph,
carrying about 8kJ of kinetic energy, and have no brakes or steering to
avoid dogs and children, as well as ignoring other pedestrians and
cyclists who are forced to scatter out of your irratic course in your
arrogant quest, it's not "cool".

Oh, get a grip. If you're anything like a reasonable cyclist you're every
bit as in control of your bike no hands as with your hands on the bars,
and getting you hands onto the bars in order to brake is a matter of a
moment.

Hell, if you can drive a car using a mobile phone it should be easy peasy!

Peter Clinch said:

Simon Brooke said:

Oh, get a grip. If you're anything like a reasonable cyclist you're every
bit as in control of your bike no hands as with your hands on the bars

Well, up to a point, Lord Copper, but the slaient point is it's
good /enough/ that the Daily Mail isn't conducting a Hate campaign
against these awful no-hands cyclists. Which means it /is/ pretty
safe! ;-/

I'm sure that the pavement cycling tossers who slalom around elderly
pedestrians are awfully safe too, but is that the whole point?

Don Whybrow said:

Tony Raven said:

Paul Weaver wrote on 02/08/2006 11:22 +0100:

Quoted message said:

It takes 400J to fracture a skull, less to fracture ribs. While in a
collision we can hope that the errant cyclist will take the full force
and die, preferably slowly and painfully, sadly it's likely the child
he (or at that height the solid inflexible bike) plows into will be the
one sustaining the most damage.

700-1000J actually and all that energy has to be applied to the skull.
Gurdjian, E.S., Webster, J.E. and Lissner, H.R., "Studies on skull
fracture with particular reference to engineering factors" Am. J. Surg.
78(5), 736-742 (1949)

Is that for an adult skull?

How much to fracture the skulls of children?

What are you planning?