Unsprung weight ?

Retrobob- Yeah, but you can _purchase_ the bike. Fitness is much harder to
come
by. BRBR

reality, what a concept.

Peter Chisholm
Vecchio's Bicicletteria
1833 Pearl St.
Boulder, CO, 80302
(303)440-3535
http://www.vecchios.com
"Ruote convenzionali costruite eccezionalmente bene"

SuperSlinky wrote:

However, rotating weight is more
important than static weight, so reducing the weight of tires, tubes and
rims is the best place to shave grams for pure performance. Other than
that, a pound on you is going to have the same effect as a pound on the
frame. Having the pound on the frame might actually be better, because
the pound on you results in a higher center of gravity.

1) The bicycle is only a small percentage of the bike + rider system
weight. And weight at the perimeter of the wheel must be accelerated
to a maximum of twice the bike's linear speed-- mass inside the outer
diameter get accelerated less. And bicycles spend only a tiny
fraction of their time, and an even tinier fraction of the rider's
energy, accelerating.

So even of the small amount of energy that a cyclist uses to
accelerate, it's a miniscule portion that gets allocated to the
wheels. For instance, assume a 180lb rider on a 23lb bike with 5lb
wheels. Assume that the wheels require 1.6x the energy to accelerate
that an equal non-rotating mass would. That means that only 1.4% of
just the work required to accelerate is used to spin the wheels.
Considering that the work required to accelerate is no more than a
single-digit percentage of the rider's output even in stop-and-go city
riding, that isn't very much.

Then any weight you save in the wheels will be at most a very small
percentage of the previous wheel weight.

If you had, say, a 400g chunk of cheese in one hand, and a 400.04g
chunk of cheese in the other, could you tell which one was lighter?
(Answer: the one with the carbon fiber wrapper. :^D ) That's more
or less the proportional difference in output required between the
hypothetical bike I mentioned, and one with 10% lighter wheels.

2) High center of mass helps handling in a bike. The reason is that
the bike must be moved between the center of mass and the center of
mass's impact point on the ground in order for the system to remain
balanced. For bikes of equal overall weight, the one that carries its
mass closer to the rider (that is, higher) will handle better.

Low C of G is car-think. Single-track vehicles (bikes) benefit from
having the mass centralized for better rotation about the longitudinal
axis.

Chalo Colina

Blair P. Houghton wrote:

Ah. The question is, "what's the difference between 5 lbs
bolted to the bike, and 5 lbs in my backpack?"

I think the answer is, "You'll suffer from the weight
on you more, because there's a lot of motion your body
undergoes that adds nothing to the transfer of energy to
the cranks."

Plus carrying a heavy backpack is a pretty sure-fire way to get a sore
arse (as we call it this side of the Atlantic). When you're riding,
that extra weight is resting on your sit-bones instead of your bike.

Chalo wrote:

Low C of G is car-think. Single-track vehicles (bikes) benefit from
having the mass centralized for better rotation about the longitudinal
axis.

I've seen a theory that high-up weight is better on a bike because the
bike balances like an inverted pendulum, and extra weight increases the
period of oscillation. That may be true in theory, but anyone who's
ridden with an occupied child seat will disagree that high-up weight
alone is beneficial for handling!

Jim Blackburn suggested that the weight should lie around a diagonal
line roughly between the front hub and the top of the rear rack - so
front lo-riders are better than a front rack, but it's OK to have the
load carried higher at the rear (so you can use the top of the rack with
impunity).

Zog The Undeniable Wrote:
Blair P. Houghton wrote:

Ah. The question is, "what's the difference between 5 lbs
bolted to the bike, and 5 lbs in my backpack?"

I think the answer is, "You'll suffer from the weight
on you more, because there's a lot of motion your body
undergoes that adds nothing to the transfer of energy to
the cranks."

Plus carrying a heavy backpack is a pretty sure-fire way to get a sore
arse (as we call it this side of the Atlantic). When you're riding,
that extra weight is resting on your sit-bones instead of your bike.




Every time that you get out of the saddle you can have that additiona
5lbs
adding to the pressure on the pedal instead of looking for a free rid
when
bolted to your bike

--
n crowley

Blair P. Houghton wrote:

Retro Bob wrote:

Yeah, but you can _purchase_ the bike. Fitness is much harder to come
by.

I just bought 2 years at LA Fitness for $595 flat. $100/year
to renew thereafter. (The salesguy actually said people turn
this deal down. Nutbars is all I can think.)

Yeah, why go to the trouble of preparing fresh food when kibble is so
much easier?

Working out in a gym is a terrible substitute for, say, riding your
bike. It's exercise, but that's all it is. No transportation, no
change of scenery, no fresh air or sunshine, no exploration involved.
You can't stop to smell the flowers when the only smells around are
other jocks' sweaty funk and air "freshener".

Going to a gym reminds me of the "dating simulator" games that are
popular in Japan. It's missing out on the real thing, and paying for
the privilege!

Chalo Colina

On Fri, 17 Sep 2004 06:39:46 +1000, n crowley
wrote:


Zog The Undeniable Wrote:
Blair P. Houghton wrote:

Ah. The question is, "what's the difference between 5 lbs
bolted to the bike, and 5 lbs in my backpack?"

I think the answer is, "You'll suffer from the weight
on you more, because there's a lot of motion your body
undergoes that adds nothing to the transfer of energy to
the cranks."

Plus carrying a heavy backpack is a pretty sure-fire way to get a sore
arse (as we call it this side of the Atlantic). When you're riding,
that extra weight is resting on your sit-bones instead of your bike.




Every time that you get out of the saddle you can have that additional
5lbs
adding to the pressure on the pedal instead of looking for a free ride
when
bolted to your bike.

Dear Norman,

Regrettably, you first have to hoist that additional 5
pounds up into the air when you stand up.

You also have to repeat the process each time the pedal
reaches the bottom.

This illustrates some of the difficulties with perpetual
motion theories, but rest assured that an army of interested
parties is working tirelessly on fixes.

Carl Fogel

"Zog The Undeniable" wrote: I've seen a theory that high-up weight is
better on a bike because the bike balances like an inverted pendulum, and
extra weight increases the period of oscillation. (clip)
^^^^^^^^^^^^^
Nope, not even in theory. An inverted pendulum does not have a period. It
falls over. For a pendulum to hav a period, gravity must act to OPPOSE the
swing of the pendulum. An inverted pendulum, or a bicycle, falls over
because gravity aids the swing.

carlfogel wrote: (clip) This illustrates some of the difficulties with
perpetual motion theories,(clip)
^^^^^^^^^^^^
What a shame! If this worked, helmets could be made heavy instead of light.
Riders in the Tour de France would all be seen wearing backpacks.

Chalo wrote:
Blair P. Houghton wrote:
I just bought 2 years at LA Fitness for $595 flat. $100/year
to renew thereafter. (The salesguy actually said people turn
this deal down. Nutbars is all I can think.)

Yeah, why go to the trouble of preparing fresh food when kibble is so
much easier?

Working out in a gym is a terrible substitute for, say, riding your
bike. It's exercise, but that's all it is. No transportation, no
change of scenery, no fresh air or sunshine, no exploration involved.
You can't stop to smell the flowers when the only smells around are
other jocks' sweaty funk and air "freshener".

Going to a gym reminds me of the "dating simulator" games that are
popular in Japan. It's missing out on the real thing, and paying for
the privilege!

1. Aerobics instructors in halter tops.
1. Aerobics instructors in halter tops.
1. Aerobics instructors in halter tops.
2. I have some upper body muscle and I want to keep it.
3. If I get hurt, whether due to riding or lifting or running
from jealous husbands, I can still go to LA Fitness to swim.
4. There's research showing that older men whose only real exercise
for several decades was cycling will have significantly higher
incidence of osteoporosis; the cure? Weight-bearing exercise.
Turns out, using your legs that much for that long eats bone
from your upper body the same way it eats muscle.
5. Legs need days off, too.
6. 3 days on the road, 1 day at the gym; 4 days on the road,
1 day at the gym; 2 days on the road, 1 day at the gym;
3 days on the road, 1 day at the gym; and so on...
1. Aerobics instructors in halter tops.

--Blair
"And some of them are chicks."

P.S. Honestly, almost any woman looks good at the gym. I'm
old enough to know that the effort is the really sexy part.