Electric-Assist Bikes and Trikes

Dr. Gabe Mirkin

I predict that in the next few years, virtually all cyclists will have motors on their bikes. I think that you can get a better training effect with a motor than without it. 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
• any condition that requires you to limit your exercise, such as irregular heartbeats (check with your doctor)
• lack of conditioning for any reason
• fear that you will not be able to keep up with other riders

Electric-assist bikes can improve the training programs for cyclists at all levels. They can usually be adapted for people with special needs or disabilities, and can make it possible for people who have not ridden in years to get all of the benefits of cycling.

Our Tandem Trike
Diana and I have been passionate tandem bicycle riders for 28 years. I am 84 and Diana is 77. We ride more than 150 miles a week. Five years ago, in March 2014, we rode into a pile of sand while going about 20 miles an hour, and crashed. I was not hurt, but Diana broke her hip, pelvis, shoulder and five vertebrae, and surgeons had to install a significant amount of hardware in her body to put her back together. She has osteoporosis and rheumatoid arthritis, which means that another crash would probably have even more serious consequences.

Gabe and Diana Mirkin ride their tandem bicycle.

We certainly were not going to give up riding bicycles, so our friend Larry Black, of Mt Airy Bicycles in Maryland, sold us a recumbent tandem tricycle. It is much safer than a regular upright two-wheeled tandem, since it has three wheels (two in front, one in the back), and is much lower to the ground. However, we immediately learned that the tandem tricycle went at least four miles per hour slower than our upright tandem with the same effort:
• It weighs 83 pounds, compared to our 26-pound upright bike
• The friction from its long front timing chain and long derailleur chain cause a tremendous loss of energy
• The smaller 20-inch wheels, compared to the upright’s 27-inch wheels, have greater resistance
• We cannot stand up, so we get no help from gravity when going up hills or accelerating after a stop

Diana and Gabe Mirkin on their recumbent tandem.

We Got Left in the Dust
We couldn’t keep up with our group of tandem riders who average 17-20 miles per hour and go much faster than that when they start to sprint. So we spent the first four months riding alone and hating it. On every hill climb and on every stop, 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.

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 lives and helps to prevent many diseases, 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 tandem trike 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, they have to spin the pedals at a fast cadence. Most knowledgeable bicycle riders try to spin their pedals at a cadence of more than 70 revolutions per minute, and most racers try to keep their cadence above 90 revolutions per minute. I tried lowering the gear ratio, to reduce the resistance of the pedals so we could 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 and prevent us from getting 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 4-5 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 of the wheel and can be put into any size of bicycle wheel. This motor has solved our problems and we are delighted with it.
• We can keep up with our group
• We get great workouts because we are the primary driving force on the pedals
• We can stop or slow down safely and know we will be able to catch up
• Carrying two batteries, we can go on 70-mile rides

Diana rides in the front (captain’s seat) and controls the steering and brakes, while I sit in the rear (stoker’s seat) and control the shifting and the motor. 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. I turn the motor on by twisting the throttle on my handlebar. We use the motor assist only when we have to accelerate when we:
• start up after stopping,
• climb hills, or
• if other riders start to pull away from us.
The rest of the time I keep the motor off.

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

How the Motor Gives 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 didn’t have a motor, our pedals would slow down so much that we would not gain the maximum training effect.

The Need for Interval Training
We ride with our group of PANTHERS Tandem Club members three days each week. On the other days, I ride my upright single bike without a motor, and Diana rides on her single trike.

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. Two or three days a week, I do the following interval workout on my single bike:
• a 5-10 minute warm up of slow riding followed by a gradual increase in speed
• a hard interval of 25 pedal rotations (about 30 seconds), fast enough to leave me short of breath
• slow pedaling until I recover my breath, usually about the same distance as my fast interval
• repeats of hard intervals followed by complete recovery of my breath until my legs start to feel heavy or hurt
• 5-10 minutes of slow miles to cool down
In my interval workouts, I usually finish between 20 and 30 hard 25-pedal-rotation intervals.

My Recommendations
Electric-assist bikes or eBikes are now widely available in all styles and price ranges, or your local bike store can probably retrofit your existing bike with a motor.

I think that the key to using an electric motor for a fitness program is to use it only as much as you need it to maintain a cadence of 70-90 rpm. 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
You should be using your own muscles to move your bike, and just get that extra help from the motor. If you have a pedal-assist type of bike, use it at a setting that challenges your muscles and helps you when you need it. You can do intervals (decribed above) on an eBike, but you will need to experiment with the settings and timing to get the most out of your workout.

If you have not yet ridden on an eBike, go to your local bike shop and try one out. I predict that you will love it.

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.

Dr. Gabe Mirkin is a Villager. Learn more at www.drmirkin.com