High Sierra 2High Sierra 3High Sierra 4High Sierra 5
OwnerKraig Schultz
Owner's Other EVs1975 Honda CB-125S
Human-Electric Hybrid
Sail Trike
2008 Custom BugE
Tilting Delta Trike
Schultz Engineering Delta-11
Motorized Mtn Bike 1 - Hummer
1987 Kann Linear LWB
1990 Ford Festiva
2015 Nissan Leaf SV
LocationGrand Haven, Michigan United States map
Vehicle1987 Schwinn High Sierra
Modified to Mount Sparrow Hub Motor to chain drive crank
MotorCrystalyte Sparrow Permanent Magnet DC
Scratch and dent wider than normal "Rear" Sparrow Motor with Free wheeler on it.
DrivetrainSparrow Hub Motor
Batteries12.00 Volt, Lead-Acid, Gel
System Voltage48 Volts
DC/DC Converter
None Used.
InstrumentationShunt with volt meter
Top Speed25 MPH (40 KPH)
Easy acceleration in all gears, like going down a hill all the time.
AccelerationVery strong for a bicycle
Range15 Miles (24 Kilometers)
Watt Hours/Mile28 Wh/Mile
Draws 18 amps at 48 volts at 20mph
Draws 28 amps at 48 volts at 25mph
EV Miles
Current:50 Miles (80 Kilometers)
    As of 12/30/2012
Seating Capacity1 adult
Curb Weight100 Pounds (45 Kilograms)
60 lbs Lead acid
12 lbs Hub Motor
12 lbs Brackets
TiresStandard mountain bike
Conversion Time1 week
Conversion CostBrackets made from scrap metal. Had to borrow crank from another bike for experiment.
Additional FeaturesThe setup was direct drive to my front chain ring meaning if the motor was running the pedals were turning. This limits the max speed of the bike to the the max geared speed of about 25mph. The motor had plenty of power left and could spin the pedals faster than I could keep up. So, I'd either need taller gearing on the bike or need to setup the motor to drive the rear wheel directly.

With Motor off, there is a free-wheeler, so the bike can be pedaled with no motor power.

This was my second attempt a motorizing a mountain bike back in September 2009.

The only reason I was using such heavy and large batteries is because they were free and sitting around in my workshop doing nothing.

1. I tested this same hub motor when it was in a 20inch wheel on my LWB Linear recumbent. Acceleration was slow and top speed was not all that great.

2. This test was to see if this hub motor would work better when driving through a transmission. And the answer is yes. Acceleration and hill climbing are greatly improved.

3. However, it's max speed is still limited by the gearing on the bike (because if the motor is running the pedals must turn). And this makes it not work for what I want to accomplish. I want higher speeds (25-30mph) to reduce my commute time with no sweat on the trip to work.

4. I like the cruise control feature, but it should not be used with a direct drive system. It's too easy to forget to disengage the cruise when you want to stop pedaling.

5. The direct drive forced pedaling was good for exercising, but resulted in me being sweaty when getting to work which is what I'm trying to avoid.

6. The direct drive worked nice and was easy to control and made my average speed increase from 15mph without motor to 22mph+ with the motor

7. At 25mph motor was pulling 30AMPs! Way more than my electric moped at this speed. So, the upright riding position and poor aerodynamics of this setup are apparently killing me for power consumption

8. Need full suspension when riding with +80 pounds of stuff mounted on the bike

9. Weight was fine and although I could feel it when taking off or trying to lift the rear end of the bike when moving it around, when pedalling without the motor running, my average speed was about the same.

10. So, I can carry a lot of cargo on my bike on flat roads at a steady speed without much penalty. However, if I was doing a lot of starts and stops and hills the extra weight would be quite a drag.

11. Chain tensioner as part of system would be nice. I had some problems with chain jumping off. A nice spring tensioner would allow chain to be snug but not tight
Observation: When pushing full power on this setup I noticed a lot of chain ring deflection.

12. Bicycle chain and chain rings are not built for 2HP+ forces. Should use heavier components when using over 2HP motors.

13. It makes sense to pay attention to 100+ years of bicycle, moped and motorcycle development. Mopeds and motorcycles are equipped with heavier duty wheels, suspension and drive chains to match power and velocity.

14. Hub motor should be in wheel to give simple, quiet operation. I should just purchase a BRUTE hub motor and install it in place of the rear wheel of a fully suspended mountain bike. This would give me high speed commutes (30mph+), allow for pedalling and exercise on the way home.

15. I would still need to install larger chainrings on the bike to allow pedalling in the 25-30mph range.

16. Due to extreme heavy weight of the lead acid batteries, the drive system was removed from this bike to allow me to ride it in it's OEM form.

code by jerry