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Our Electric-Assist Bicycle

Diana and I are passionate tandem bicycle riders. We live in The Villages in Florida, the largest retirement community in the world, and we ride every day with a group of serious tandem-bicycle riding couples. Last March we were riding our tandem very fast, drove into a deep pile of sand on the road and crashed. I was not hurt, but Diana broke her pelvis, hip, shoulder and wrist and surgeons had to install a significant amount of hardware in her body to put her back together. She has severe osteoporosis. This means that the next crash could have even more serious consequences.

We Bought a Recumbent Tandem Tricycle
We certainly were not going to give up riding bicycles. Bicycle riding is our passion. So our friend Larry Black, of Mt Airy Bicycles in Maryland, sold us a recumbent tandem tricycle, which is much safer than our regular upright two-wheeled tandem. It has three wheels (two in front, one in the back), so we cannot fall.

However, we immediately learned that the recumbent tricycle rides at least four miles-per-hour slower than our upright racing tandem with the same effort:
• It weighs 83 pounds, in comparison to our 26-pound upright bike.
• The friction caused by its long front timing chain and long derailleur chain loses a tremendous amount of energy.
• The smaller 20-inch wheels, compared to the upright 27 inch wheels, have greater resistance.
• The wheels do not turn on their hubs as smoothly and easily as the wheels on our upright tandem.
• We cannot stand up, so we get no help from gravity when going up hills or accelerating after a stop.


We Got Left in the Dust
We couldn't keep up with our group of tandem riders who average close to 20 miles-per-hour and go much faster than that when they start to sprint. So we spent the next four months riding alone and hating it. When we tried to ride with other serious tandem-riding couples, we would be dropped every time we had to pick up the pace after slowing down. On every hill climb, and on every stop at traffic lights and intersections, we could not increase our speed fast enough and the other couples would pull away from us. We needed extra help whenever we had to accelerate.

We Couldn't Train Properly
Even if we were willing to ride alone, we still had a problem. We are serious bicycle riders and understand training. We know that exercise prolongs life and prevents disease and that the more intensely you exercise, the greater the benefits. We know that an intense workout requires us to become short of breath and burn our leg muscles. The recumbent bike offered so much resistance to our pedaling that our legs would burn, but we could not spin the pedals fast enough to become short of breath. You need to train at your "lactate threshold", to be able to compete and to gain maximum health benefits. You can't really become short of breath on a bicycle unless you spin your pedals at a fast pace.

Bicycle racers know that to go fast, you have to spin your pedals at a fast cadence. Most knowledgeable bicycle riders try to spin their pedals at a cadence of more than 70 revolutions per minute. Most racers try to keep their cadence above 90 revolutions per minute. We tried to lower our gear ratio, to reduce the resistance of the pedals and be able to keep up our cadence, but that caused us to have such low pedal resistance that we would spin the pedals so fast that the bike would travel even slower so that we couldn't even get a decent workout. On hills, we would drop our gears as low as we could to raise our cadence over 70, and we would slow down to four or five miles per hour, which was incredibly painful to our minds as well as our bodies.

Electric Motor to the Rescue
Larry Black got us an electric motor from Falco Motors. They make motors that fit onto the hub (middle) of the wheel and can be put into any size of bicycle wheel. This motor has solved all of our problems and we are delighted with it. :
• We can keep up with our group.
• We get great workouts as we are the primary driving force on the pedals.
• We can stop safely at intersections because we know we will be able to catch up.
• The battery lasts about 25 miles on one charge,
• Carrying a second battery, we can go on 50-mile rides.


How We Use the Electric Motor
On our trike, Diana rides in the front (captain's seat) and controls the steering, brakes and shifting. I sit in the rear (stoker's seat) and control the motor with a throttle. On a tandem trike, the strongest person should sit in the back seat because the person with the strongest legs generates the most power, and the back pedals connect directly to the drive chain. The rider in front loses a lot of power from the very long timing chain that runs from the front pedals back to the rear pedals.

The motor stays off until I turn it on by twisting the control on my handlebar. We use the motor assist only when we have to accelerate when we:
• start up after stopping,
• increase speed after slowing down for a traffic light, circle or any other reason,
• climb hills, and
• when people riding with us start to pull away from us.
The rest of the time the motor stays off.

We start off with a short push from the motor. Then we adjust the gears to achieve a cadence of about 90 pedal rotations per minute. We do all our gearing by following the resistance on the pedals. If the resistance increases, we do not wait for the cadence to slow down; we immediately lower the gear ratio. We constantly try to keep the pedal cadence at about 90 by adjusting the gears to the resistance of the pedals. When we start to spin much over 100 pedal revolutions per minute, we increase the gear resistance. When the pressure on the pedals increases significantly and we realize that a change in gearing will not keep up the 90 cadence, I twist the throttle to turn on the motor and it makes the wheel spin faster so the cadence does not slow down.

How the Motor Give Us a Better Workout
By not having to slow down when the pressure on the pedals increases, we are able to keep a fairly-constant 90 cadence. This puts us at our "lactate threshold", the ideal training level. When we are barely getting enough oxygen to meet our energy needs, we are exercising at the maximum capacity that we can maintain and still not have to slow down or stop. If we go any slower, we will meet all our needs for oxygen comfortably and not gain the maximum training effect. When we exceed our needs for oxygen, we have to slow down to recover.


The Need for Interval Training
I also do interval workouts on my single bike without a motor. To gain maximum ability to take in and use oxygen, you need to go into severe oxygen debt and gasp for breath. However, when this happens, you have to slow down and recover. Competitive athletes do intervals in which they pedal, run, skate or swim a certain distance at near maximum effort, and gasp for breath. Then they slow down until they recover their breath and again repeat the maximum effort that drives them into severe oxygen debt. Three times a week, I do the following interval workout:
• a 5- to 10-minute warm up of slow riding followed by a gradual increase in speed,
• a 50-pedal-stoke interval so fast that it leaves me short of breath,
• slow pedaling until I recover my breath, about the same distance as my fast interval,
• repeats of alternating 50-pedal-stroke hard intervals followed by complete recovery of my breath until my legs start to feel heavy or hurt, then
• ride a few slow miles to cool down.

On my three-times-per-week interval workouts, I average between 20 and 35 very intense 50-pedal-stroke intervals. Diana does a similar workout on her single trike. The next day, we ride 25 to 30 miles on our motor-assisted tandem tricycle almost flat-out with our large group of tandem couples.

Who Can Benefit from an Electric-Assist Bike?
Anyone who has difficulty accelerating a bike will benefit from an added boost from an electric motor. Consider an electric assist motor if you have:
• weak muscles
• irregular heart beats or any condition that requires you to limit your exercise (check with your doctor)
• lack of conditioning from being out-of-shape
• fear that you will not be able to keep up with other people in your group

The key to using an electric motor for a fitness program is to use it only when you need it. It should not be used all the time. You can use the motor to help:
• start moving from a stop
• accelerate after you have slowed down
• go up steep hills
• catch up if you get left behind
At all other times you should use your own muscles to move your bike.


Caution: Intense exercise can cause heart attacks in people who have blocked arteries leading to their hearts, irregular heartbeats or other abnormalities. Heart attacks during exercise are more likely to occur when a person starts a new exercise program or increases the speed or duration of exercise. Check with your doctor.

Checked 11/22/15

January 25th, 2015
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About the Author: Gabe Mirkin, MD

Sports medicine doctor, fitness guru and long-time radio host Gabe Mirkin, M.D., brings you news and tips for your healthful lifestyle. A practicing physician for more than 50 years and a radio talk show host for 25 years, Dr. Mirkin is a graduate of Harvard University and Baylor University College of Medicine. He is board-certified in four specialties: Sports Medicine, Allergy and Immunology, Pediatrics and Pediatric Immunology. The Dr. Mirkin Show, his call-in show on fitness and health, was syndicated in more than 120 cities. Read More
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