Date: Thu, 27 Nov 1997 11:24:29 -0500 (EST)
Subject: Dutch bike with Sachs power-assist?

I'm new to the group - glad to be among such distinguished company.  I have
two things to share.
	Last year in Amsterdam I was passed by a woman riding a Dutch bicycle
with a Sachs power assist on the rear hub.	We were riding on a bike trail
and her machine was very quiet, and looked very sophisticated.	I stopped in
at a bike store and received a brochure.  30cc two stroke engine drives a 26"
magnesium wheel, quality components even has a catalytic converter.  Bike
weighs 32 Kg, normal Dutch bicycles weigh in at around 20 Kg, so it doesn't
add too much weight.  I don't remember them being too expensive.
	This year I was out in France in the Burgundy countryside and watched a
fellow ride by with one, pedaling without the engine.  I showed this to my
wife, who hates mopeds and she liked this idea a lot.  We are avid cyclists
but hate the hills.
	I didn't buy one because I don't know if it is legal in my home state.
 OK, I probably will never be stopped but you know I'm American, you know,
boy scout, obays laws, that sort of thing.
	Here are my questions on this.	Does anyone have experience with one of
these machines.  If it works as well as I have seen, why aren't they popular
in the US?
	Second item - I have trouble believing that an electric power assist is
the answer.  I live off the power grid on a sailboat.  We use solar power
extensively for lights and such but we cook with propane.  Trying to cook by
storing electrical power and then powering an electric stove is possible, but
not practical.	Batteries are very expensive in the US and ridiculously
expensive anywhere else.  I think powering a bicycle using electricity is a
similar problem, just doesn't seem efficient to my non-engineering mind.  You
need to pound a lot of power into a battery and then run it dry, these
charging cycles would be brutal on a storage battery.  I must be missing
something because it appears a lot of companies are developing electric
Mopower to you
Rich Haslacher

What would be my ideal vehicle?

This would be a near recumbent vehicle vaguely like a Honda Goldwing, but a
bit slimmer, smaller and with linear pedals. These would control the motor
with the same type of amplifier concept like the Velocity, except that no
shifting at all would be required, an inclinometer measuring the vehicle's
gradient and adjusting power and gearing accordingly. The software control
would also allow some user settings, like degree of amplification, top
speed, etc.

It would have two wheels plus two automatic "training" wheels for parking
and very slow speeds, or two rear wheels not very wide apart and arranged
for allowing the vehicle to tilt.

There would be a fairing which could be either hidden or deployed,
functional, good-looking, light and strong.

There would be a trailer concept allowing the attachment of both trailers
syled to the vehicle and utility trailers for real bulky stuff.

The drive would be electric and the range adequate. There would be hybrid
modules and solar cells available on the trailer for touring.

All of this could be made today with existing technology. The difficult bit
would be the fairing design and the price.

Theo Schmidt
Cris ( wrote:

I agree about the health issue and I feel that a
helper motor (helper only) on a bicycle doesn't create
less exercise.	In fact I like to cruise around the vacant
industrial parks on Sundays and head off road (using the
motor) along the railroad tracks looking stuff that may
have fallen off the trains and trucks that are around
during the week.

I've a mountain bike with two different weed-eater motors
that interchange depending what kind of riding I'm going
to do.	I use urethane as well as Delrin plastic which I
have threaded 4-40 socket head cap screws into and use their
heads to grip the tire.  I also have a home made electric
with two 24v motors driving the front wheel of a Schwinn
5-speed cruiser bike and another bike with a Zap motor on it.


John  ( wrote:

With your unique experience on both electric and
gas assist units would you help me understand the ZAP
unit's operation better?  How difficult is it to disengage
while riding?  And what's its real range and performance?

Cris wrote:

The Zap unit is a friction drive unit. It has two permanent
magnetic motors attached to each other (armature to armature)
with the drive roller in between.  This unit is attached to
the bike with a clamp that squeezes the seat stays.

The motor(s) hangs down underneath the seat stays just in
front of the rear tire. It must be positioned so it will not
contact the rear tire while hanging vertical via gravity.  When
the motor control (3 speed) is activated (using momentary finger
switch) the motor torque's back and swings into contact with
the rear tire.	The motor will pull itself into the back tire
and stay there until the power is turned off.

Motor position is very critical!  These motors (at least the
one I own) will not work on fat tires (2.125x26) due to a lack
of space between the motors.  Also, there is a bracket that can
be manually swung into place which locks the motor against the
rear tire (for down hill recharging of the battery).  Don't plan
on doing much battery recharging by pedaling faster than the
motor can propel you in low speed.

BTW, since I fried my first ZAP 17amp hr. battery (used it on
another project and smoked it, arrrrggg!), I'm using a 34 amp
hr. deep cycle gel cell battery mounted to a luggage rack on
the back of the bike.

My range is real good, with plenty of power. The battery
weighs 25 lb., but I don't really notice it after awhile. The
electric assist is a blessing!


John wrote:

That was the BEST description of how a ZAP works I've ever
run across. You cleared up my questions about it's mechanics.
Thank you for taking the time to put that together.

It sounds as if the ZAP could be used intermittently with
little trouble -- thus extending it's range. Hit the switch
for hills, turn it	off on the level and downhill slopes. No
interference to the tires  when it's off... Guess the
preceding is actually a question. Could it work that way
in real life?

Cris wrote:

To answer the question: Yes!  You don't even know the ZAP
is there (unless you rub your leg against one of the motors
while pedaling (no big deal)). It comes to life when your
push the momentary switch, though, and you know it's there!

Only the weight of the battery is a clue and it's something
that you get used to right away. Riding a heavier bicycle than
normal (26 pounds is normal, I guess) is not a bad thing.

Look at it this way, probably 40% of one's daily round trip
is down hill and the same amount is up. With more weight you
coast further down hill (unless you must stop often) and with
low gearing and the ZAP uphill is a breeze.

I rode downtown today (lots of hills) and didn't notice the
weight, except for bumps.

Feel free to post any of my messages to the list if you think
others might be interested.

John wrote:

How you compare the gasoline assists to the electric's?
Are they in different leagues from one another, or are
they interchangeable in function for you?

Cris wrote:

Since I have had the ZAP for almost 2 years, I guess I can
speak from experience.	I haven't had any "bad" things happen
with the unit, however, I think there is room for improvement.

At $500, the controls could use more durable switches for the
handle bars. The switches do not appear to be weather proof
and the plastic (yuck!!!) clamps that they are housed in are
fragile. This appears to be an off the shelf component (I
could be wrong about that).

The stampings that are used to hold the motor to the seat
stays function as a clamp and are not strong enough.  They
bend with little clamping force applied.

My motor has not slipped, but, that's because of the stick
on foam rubber pads applied to the clamp brackets.	The foam
will not last forever.... but maybe that's the idea.

The friction drive eats tires.	The size of the aluminum
oxide crystals (I think that's what they use???) or called
grit size needs to be more aggressive, that is, larger, but
not by much.

On the other hand, the motor, battery case, cables, and
finish are first class!!!

As far as comparing electric to gas, there is no comparison,
because my gas setup is home made and purely experimental.
The ZAP is more practical for the short ride to work and back.

It's quiet and doesn't attract attention.  That feature allows
one to concentrate on the road and surroundings (cars, dogs,

The gas (weed-eater motors) are noisy, vibrate, temperamental,
and stink (fumes).	But, they are light weight, not hindered
by having to recharge, and are fun because you can tinker with
them for performance modifications.

Until some well defined laws come into effect in this state
[ed. Texas], I will always be worried about getting busted by
the heat (thinking I'm driving a moped, motorcycle, etc.) for
not having tags, inspection, safety equipment (lights, horn,
etc.), insurance (real bad!!!), helmet (motorcycle, not bicycle)
and probably some other stuff.

I've got to go, but I'd like to add to this later.

... A speed limit for auxilary-powered bicycles makes a
world of sense if energy resource conservation and
personal health are important to us. A bike rolls downhill
under the influence of gravity. Along the level our muscle
power alone is more than sufficent to propel an vehicle at
reasonable speeds for hours at a time. That leaves inclines
and high winds as THE two major reasons for calling
on a helper power source. Both represent intermittant

Higher top speed for most HPVs will be most responsibly achieved
via aerodynamics and improvements in the human drive train.

More and more I'm begining to realize that people are not static
performance machines. Our output to the pedals, our individual
"horsepower" and "range" should not be fixed on a graph
like an artifical motor is. In other words, the average human
is a myth created by statistics. No two people have the same
physical ability or pyschological motivation. It is most important
to acknowledge that all humans can and do change their abilities
on a daily basis.

After spending the last 20 years needlessly locked in a chair
-- in a building or in a vehicle -- I've experienced a
transformation of sorts, a mid-life process of rediscovery.
Last January riding a normal bicycle 1 mile unassisted represented
a major physical effort. With the benefit of 7 months, nearly a
1,000 miles and a little TUTORING from an motorized assist I now
throughly enjoy -- unassisted -- 10 to 20 mile rides several times
a week. And, many of those rides (gasp) are on a $80 Huffy
21-speed. Squeak, squeak, squeal...

I was well below "average" fitness a short time ago, getting
closer to the middle of the curve for all humans. Hiding the
car keys provides drill-instructor-like motivation. And
a copy of John Tetz's principles for AHPV produces enough
"good guilt" to stay my hand from the engine controls. This
allowed the Dimension Edge kit to wither away from an
initial 85 MPG to over 400 MPG at the lastest milage reading.

My ultimate goals; no power-assist needed, no automobile slave
to feed, to cycle long distances (circle the globe?), laugh daily,
to meet my Great-great-grandchildren and to be happy in the
spirit of Jeanne Clament, 122-years-old, a cigerette-puffing,
beer/wine-sipping bicyclist.

john (with 80+ years to go)
I think the best power assist system would be modular.	This might help solve
many of the complaints or weakness' of each of the current systems.

By modular I think a design that includes:

1. A quick release motor.
2. Modular battery packs, several smaller batteries rather than one big one.

How would this systems solve the current problems faced by rides?

1.	I can use no system on many days when I ride to the office and don't need to
go elsewhere.  (No motor, no battery)  I have showers and carry a change of
cloths each day on my trike.

2. On days when I need to get there faster, run a short errand, or take a route
that includes many hills.  I can use the motor and one battery.

3. On days where I need to run an errand in the middle of the day in my work
cloths I can carry two batteries and be an ev during that part of the day.

Currently I ride most days, but find that I take a car when I have to run
errands.  This would let me use my trike almost all the time.

I don't think any one systems is right for all types of trips, but with a
modular system you may be able to ride more of the time.


Timothy Taylor, Ph.D.
Biological Engineering
University of Missouri-Columbia


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