Who-hoo!

Tony B said:

I was just giving my Cannondale a bit of TLC and happened to notice the
max speed on the cycle computer has got up to 63.7 kmh!!!

Wonder when that was?

Of course it's about now I remember the speeds the really fast riders
get to, hmm...

http://www.speed101.com/now/fastest_0127_1.htm

now that's fast!

bfn,

T

My Cateye Velo 5 has registered over 190mph, but I think that was
caused by interference from something passing. Would be nice to claim
that, but...

Imagine sustaining that and overtaking a Eurostar or whatever!

PhilD

--
<><

In news:[email hidden],
Tony B <[email hidden]> tweaked the Babbage-Engine to tell
us:

Quoted message said:

I was just giving my Cannondale a bit of TLC and happened to notice
the max speed on the cycle computer has got up to 63.7 kmh!!!

Wonder when that was?

Of course it's about now I remember the speeds the really fast riders
get to, hmm...

http://www.speed101.com/now/fastest_0127_1.htm

now that's fast!

And out of date...

http://www.wisil.recumbents.com/wisil/whpsc2007/speedchallenge-2007.htm

--
Dave Larrington
<http://www.legslarry.beerdrinkers.co.uk>
Kinder surprise! What's the surprise? Your children are now dead.

Tony B said:

I was just giving my Cannondale a bit of TLC and happened to notice the
max speed on the cycle computer has got up to 63.7 kmh!!!

<yeahbut> for it to be recognized by the u.r.c. committee you need to
have done it twice in opposite directions within a certain time frame.

--
Membrane

Tony B said:

I was just giving my Cannondale a bit of TLC and happened to notice the
max speed on the cycle computer has got up to 63.7 kmh!!!

Wonder when that was?

Of course it's about now I remember the speeds the really fast riders
get to, hmm...

http://www.speed101.com/now/fastest_0127_1.htm

now that's fast!

bfn,

T

Really? I hit nearly that every single day ... I did that on the
single speed on Sunday.

My record is 87kph on a MTB ... Always wanted to return to Ditchling
Beacon with a geared up road bike ... am sure I'd break 110kph ..

Now that'd be fast ...

elyob said:

Tony B said:

I was just giving my Cannondale a bit of TLC and happened to notice the
max speed on the cycle computer has got up to 63.7 kmh!!!

Wonder when that was?

Of course it's about now I remember the speeds the really fast riders
get to, hmm...

http://www.speed101.com/now/fastest_0127_1.htm

now that's fast!

bfn,

T

Really? I hit nearly that every single day ... I did that on the
single speed on Sunday.

My record is 87kph on a MTB ... Always wanted to return to Ditchling
Beacon with a geared up road bike ... am sure I'd break 110kph ..

Now that'd be fast ...

My best speed ever was on a mountain bike - 79kph. I only managed 75
down Ditchling. I think the extra weight of a fully loaded touring MTB
made more difference than the better aero of the road bike.

Good luck!

Pete

"Tony B" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

I was just giving my Cannondale a bit of TLC and happened to notice the max
speed on the cycle computer has got up to 63.7 kmh!!!

Wonder when that was?

Dunno, but it reminds me of the lovely Helms cartoon, the one where the
smiling cyclist is setting out, and his wife is explaining to the neighbour
that "he's been a happy man since I reprogrammed his computer by 10%"

Membrane said:

<yeahbut> for it to be recognized by the u.r.c. committee you need to
have done it twice in opposite directions within a certain time frame.

Or be Alan Holmes

-dan

Pete said:

elyob said:

Tony B said:

I was just giving my Cannondale a bit of TLC and happened to notice the
max speed on the cycle computer has got up to 63.7 kmh!!!

Wonder when that was?

Of course it's about now I remember the speeds the really fast riders
get to, hmm...

http://www.speed101.com/now/fastest_0127_1.htm

now that's fast!

bfn,

T

Really? I hit nearly that every single day ... I did that on the
single speed on Sunday.

My record is 87kph on a MTB ... Always wanted to return to Ditchling
Beacon with a geared up road bike ... am sure I'd break 110kph ..

Now that'd be fast ...

My best speed ever was on a mountain bike - 79kph. I only managed 75
down Ditchling. I think the extra weight of a fully loaded touring MTB
made more difference than the better aero of the road bike.

I'm not sure if you're saying the extra weight helped or hindered you. In
any case, unless I'm missing something, I don't think it would make any
difference[1], but the aero drag of luggage would probably slow you down
quite a bit.

[1] Heavy things fall at the same speed as lighter things:
http://www.jimloy.com/physics/galileo.htm

"Jim Higson" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

I'm not sure if you're saying the extra weight helped or hindered you. In
any case, unless I'm missing something, I don't think it would make any
difference[1], but the aero drag of luggage would probably slow you down
quite a bit.

[1] Heavy things fall at the same speed as lighter things:
http://www.jimloy.com/physics/galileo.htm

Where I ride a bike, I normally find this thing called "air". It's quite
useful in some ways, since my body is designed to use it as a source of
oxygen to keep me alive. In other ways it's a bit tedious, air resistance
being the thing I spend most of my riding energy on.

The thing is, due to the presence of this "air", it is no longer true to say
that heavy things fall at the same speed as lighter things. Trivial example
: coin, feather.

Who will descend faster - a rider with empty bottles on the bike, or one
with lead-filled bottles on the bike? Obviously the extra weight won't make
any difference[1] - or would it?

cheers,
clive

Clive George said:

Who will descend faster - a rider with empty bottles on the bike, or one
with lead-filled bottles on the bike? Obviously the extra weight won't
make any difference[1] - or would it?

Jean Robic thought so; see 1953 in this article
http://observer.guardian.co.uk/osm/story/0,,966185,00.html

Clive George said:

Quoted message said:

[1] Heavy things fall at the same speed as lighter things:
http://www.jimloy.com/physics/galileo.htm

The thing is, due to the presence of this "air", it is no longer true to say
that heavy things fall at the same speed as lighter things. Trivial example
: coin, feather.

Force = mass * accelleration, or f=ma

a is constant (gravity), m you can change.

The faster you go, the greater the force you need to overcome (air
resistance mainly, but some other resistances as well). Therefore,
for pelting downhill, all other things being equal, you+bike needs to
be heavier to achieve higher speeds.

PhilD

--
<><

PhilD said:

Clive George said:

Quoted message said:

[1] Heavy things fall at the same speed as lighter things:
http://www.jimloy.com/physics/galileo.htm

Quoted message said:

The thing is, due to the presence of this "air", it is no longer true to say
that heavy things fall at the same speed as lighter things. Trivial example
: coin, feather.

Force = mass * accelleration, or f=ma

a is constant (gravity), m you can change.

The faster you go, the greater the force you need to overcome (air
resistance mainly, but some other resistances as well). Therefore,
for pelting downhill, all other things being equal, you+bike needs to
be heavier to achieve higher speeds.

PhilD

--
<><

Yeahbut......

Surely as you increase mass then your acceleration (for a given
force ) will be less?

BigRab said:

PhilD said:

Clive George said:

> [1] Heavy things fall at the same speed as lighter things:
>http://www.jimloy.com/physics/galileo.htm

Quoted message said:

The thing is, due to the presence of this "air", it is no longer true to say
that heavy things fall at the same speed as lighter things. Trivial example
: coin, feather.

Force = mass * accelleration, or f=ma

a is constant (gravity), m you can change.

The faster you go, the greater the force you need to overcome (air
resistance mainly, but some other resistances as well). Therefore,
for pelting downhill, all other things being equal, you+bike needs to
be heavier to achieve higher speeds.

PhilD

--
<><

Yeahbut......

Surely as you increase mass then your acceleration (for a given
force ) will be less?

Yes, but the miracle of gravity is that it automatically applies a
bigger force to something with a bigger mass.

Air resistance on the other hand doesn't. The force it applies depends
on speed (squared, about) and frontal surface area (roughly).

So although gravity on its own results in exactly the same accelerations
on the heavy and the light bikes, air resistance results in a greater
deceleration on the lighter bike (same force, but less mass, so more
deceleration) at a given speed assuming both bikes have about the same
frontal area.

So the heavy bike ends up going faster down hills.

Ben C said:

BigRab said:

PhilD said:

On Sep 5, 12:32 pm, "Clive George" <[email hidden]> wrote:

>> [1] Heavy things fall at the same speed as lighter things:
>> http://www.jimloy.com/physics/galileo.htm
> The thing is, due to the presence of this "air", it is no longer true to say
> that heavy things fall at the same speed as lighter things. Trivial example
> : coin, feather.
Force = mass * accelleration, or f=ma

a is constant (gravity), m you can change.

The faster you go, the greater the force you need to overcome (air
resistance mainly, but some other resistances as well). Therefore,
for pelting downhill, all other things being equal, you+bike needs to
be heavier to achieve higher speeds.

PhilD

--
<><

Yeahbut......

Surely as you increase mass then your acceleration (for a given
force ) will be less?

Yes, but the miracle of gravity is that it automatically applies a
bigger force to something with a bigger mass.

Air resistance on the other hand doesn't. The force it applies depends
on speed (squared, about) and frontal surface area (roughly).

So although gravity on its own results in exactly the same accelerations
on the heavy and the light bikes, air resistance results in a greater
deceleration on the lighter bike (same force, but less mass, so more
deceleration) at a given speed assuming both bikes have about the same
frontal area.

So the heavy bike ends up going faster down hills.

For a very long hill with a fixed gradient, a heavy bike
will go faster. However a lot of the initial acceleration
will come from the cyclist putting k.e. in with his legs.
E=(1/2)mv^2, so for a fixed energy input, a lighter bike
will go faster.

If you are going down hill, and hit an up hill section, a
heavy cycle will decelerate faster than a light cycle if
both are being pedalled, as lifting up the heavy bike
needs more energy than the light bike.

Martin.

"Martin Dann" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Quoted message said:

Yes, but the miracle of gravity is that it automatically applies a
bigger force to something with a bigger mass.

Air resistance on the other hand doesn't. The force it applies depends
on speed (squared, about) and frontal surface area (roughly).

So although gravity on its own results in exactly the same accelerations
on the heavy and the light bikes, air resistance results in a greater
deceleration on the lighter bike (same force, but less mass, so more
deceleration) at a given speed assuming both bikes have about the same
frontal area.

So the heavy bike ends up going faster down hills.

For a very long hill with a fixed gradient, a heavy bike will go faster.
However a lot of the initial acceleration will come from the cyclist
putting k.e. in with his legs.
E=(1/2)mv^2, so for a fixed energy input, a lighter bike will go faster.

Doesn't take that long a hill to reach the steady state, so even assuming
you mean "fixed energy input from the cyclist", rather than taking into
account the PE change, the heavier bike wins fairly soon.

cheers,
clive

Martin Dann said:

Ben C wrote:

big snips

Quoted message said:

Quoted message said:

Yes, but the miracle of gravity is that it automatically applies a
bigger force to something with a bigger mass.

Air resistance on the other hand doesn't. The force it applies depends
on speed (squared, about) and frontal surface area (roughly).

So although gravity on its own results in exactly the same accelerations
on the heavy and the light bikes, air resistance results in a greater
deceleration on the lighter bike (same force, but less mass, so more
deceleration) at a given speed assuming both bikes have about the same
frontal area.

So the heavy bike ends up going faster down hills.

For a very long hill with a fixed gradient, a heavy bike
will go faster. However a lot of the initial acceleration
will come from the cyclist putting k.e. in with his legs.
E=(1/2)mv^2, so for a fixed energy input, a lighter bike
will go faster.

If you are going down hill, and hit an up hill section, a
heavy cycle will decelerate faster than a light cycle if
both are being pedalled, as lifting up the heavy bike
needs more energy than the light bike.

Martin.

yes i notice that on things like club runs where i'll move up the group
on downhills partly weight and partly wider tires that are less likely
to wash out on gravel etc, but any uphill bits, tend to knock one back.

still it is a club run not a race etc.

roger
--
www.rogermerriman.com

Quoting BigRab <[email hidden]>:

Quoted message said:

PhilD said:

Clive George said:

>[1] Heavy things fall at the same speed as lighter things:
>http://www.jimloy.com/physics/galileo.htm
The thing is, due to the presence of this "air", it is no longer true to say
that heavy things fall at the same speed as lighter things. Trivial example

for pelting downhill, all other things being equal, you+bike needs to
be heavier to achieve higher speeds.

Surely as you increase mass then your acceleration (for a given
force ) will be less?

"For a given force" is where you go wrong. What matters is the net force.
If I am at terminal velocity on a given hill, the net force is zero; if I
magically exchange an empty water bottle for a lead-filled one, the air
resistance does not change but the gravitational force does. The net force
is now positive; I accelerate to a higher terminal velocity.

However, generally you aren't increasing mass without changing air
resistance. The square-cube law means heavier riders tend to have a higher
ratio of mass to frontal cross section, so they descend faster. A tandem
has added an extra rider's mass almost entirely in the wind shadow of the
first rider; they descend _much_ faster. But the original question, loaded
or unloaded bike; the panniers are partly in the shadow of the legs,
partly not, probably less dense than a human rider - it's not all that
clear whether they will increase or decrease terminal velocity.
--
OPTIONS=name:Kirsty,menustyle:C,female,lit_corridor,standout,time,showexp,hilit
e_pet,catname:Akane,dogname:Ryoga,fruit:okonomiyaki,pickup_types:"!$?=/,scores:
5 top/2 around,color,boulder:0,autoquiver,autodig,disclose:yiyayvygyc,pickup_bu
rden:burdened,!cmdassist,msg_window:reversed,!sparkle,horsename:Rumiko,showrace

Clive George said:

"Martin Dann" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Quoted message said:

Yes, but the miracle of gravity is that it automatically applies a
bigger force to something with a bigger mass.

Air resistance on the other hand doesn't. The force it applies depends
on speed (squared, about) and frontal surface area (roughly).

So although gravity on its own results in exactly the same accelerations
on the heavy and the light bikes, air resistance results in a greater
deceleration on the lighter bike (same force, but less mass, so more
deceleration) at a given speed assuming both bikes have about the same
frontal area.

So the heavy bike ends up going faster down hills.

For a very long hill with a fixed gradient, a heavy bike will go
faster. However a lot of the initial acceleration will come from the
cyclist putting k.e. in with his legs.
E=(1/2)mv^2, so for a fixed energy input, a lighter bike will go faster.

Doesn't take that long a hill to reach the steady state, so even
assuming you mean "fixed energy input from the cyclist",

Yes that is what I meant. Have you ever started at the top
of a hill and just freewheeled without any pedalling, it
takes a while to get going. The lighter bike will have a
better initial acceleration, the heavy bike will have
fight wind resistance better, and have a higher terminal
velocity.

rather than

Quoted message said:

taking into account the PE change, the heavier bike wins fairly soon.

Where I live I am rarely on hills like that, and when I do
get up to terminal velocity, I normally have to slow down
for traffic lights, bends, cars etc, or I hit another up hill.

In article <[email hidden]>, Martin Dann
[email hidden] says...

Quoted message said:

Yes that is what I meant. Have you ever started at the top
of a hill and just freewheeled without any pedalling, it
takes a while to get going. The lighter bike will have a
better initial acceleration,

Why?