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Old May 29th 08, 02:23 AM posted to rec.bicycles.tech
clare at snyder dot ontario dot canada
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Posts: 87
Default ebikes: lots of bad ideas

On Wed, 28 May 2008 08:58:31 -0700 (PDT), johns
wrote:

Before I start building my ebike, I'm reading everything I can find
on what is available. So far, I'm learning more about what not to
get ..

1. Front wheel hub motors can generate enough torque
to break the front forks. So that company only
recommends rear-wheel hub motors.
2. Most hub motors .. no matter what their "power
rating" don't have enough torque to pull more than
a 4% grade.
3. Only gear motors ... even low power ones .. can
generate enough torque to pull an 8% grade.
4. ( another group ) .. Gear motors weigh about 35
to 40 pounds. WHAT ???????????
5. Regenerative braking is a joke. To recharge a
battery using RB, you would have to coast downhill
for 20 hours. Ordinarily, RB can return about 3% of
your charge.
6. Hub motors are unsprung weight. They cause a
very uncomfortable ride. The emotor should go up
between the pedals, and drive the chain.
7. Battery ratings are for flat terrain at about 10 mph.
In real life, they get about half their rated milage per
charge.
8. The average finished ebike will weigh more than 60
pounds.
9. Some of the ebike "kits" require machining of your
bikes parts in order to fit. They also require calibration
of the hub motor sensors in order to get the motor to
rotate in the proper direction. These operations can
void your kit warranty.
10. An ebike can save you $20,000.00 over 3 years,
so it is worth the $14,000.00 they are asking for it.

Sounds to me like the ebike has a ways to go.

johns



Well, I'll respond to a few of these points.

1- If the hub motor can produce enough torque to break the fork,,
either the fork is so weal it is already unsafe, and/or Number 2 has
to be wrong.

2_ If this is the case, the fork must be extremely weak and unsafe,
even without the motor.

3- Even a low powered gear motor may not be able to pull an 8% grade.
And just because it is a hub motor does NOT mean it is not a gear
motor. There are planetary geared hub motors out there.

4- Look at a Currie 450 watt gear motor. Can't weigh much more than 5
lbs. Then again, a mobility scooter motor can weigh anywhere from 5
to 40 lbs (for an aproxemately 350 watt motor) I have motors at both
ends of the scale.

5- I'd agree. Regenerative braking is oversold. It is ONLY viable with
a direct drive hub motor. Any other setup gives away too much
efficiency by having to back-drive it whenever running without power
on.

6- Yes, hub motors are unsprung weight. So are geared motors mounted
at the wheel like the Currie.
And so are ANY motor mouinted to a non-suspension bicycle.
Yes, mounting them close to the bottom bracket and driving through the
chain (allowing use of the gears) IS the most efficient - and requires
a free-wheel crankset.

7- Rated mileage on mine says "with normal pedaling" These are
ELECTRIC ASSIST BICYCLES, not electric motorcycles. I have no doubt I
can get the rated mileage if I use the motor only as an ASSIST. I was
going to find out today by attempting a 35 KM jaunt (mile is rated,
IIRC, at 20 miles maximum range) but I ended up having to cancel
because I needed to take the truck and cxover a LOT more distance in
less time.

8- Yup.

9- Machining on the bike voids the kit warranty? You need to adjust
something on the motor to make it work, which voids the warranty?
Sounds like a rather halfassed kit with no support - likely an "import
it yourself" chinese box of junk.

10- You paid HOW MUCH for it???? The marketing hype has pushed a LOT
of E-Bike prices into the stratosphere. I just bought a pretty decent
fully equipped e-bike for just over $600, all taxes in.
It has fenders at both ends, a rear carrier, stand, lights, mirror,
bell, reflectors - everything I need. It IS heavy and has a "limited"
range - as advertized - but 8 tanks of gas for my van will pay for the
bike at TODAY'S prices.
That should be doable just going back and forth to the office for one
summer.
I'm adding a 26ah battery pack on the rack to supplement the 12ah pack
for longer trips - and possibly going to 36 volts instead of 24 for a
bit more power. I'll still have under a thousand dollars tied up in
it, even buying the heavier charger required for the "premium"
batteries.
** Posted from http://www.teranews.com **
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