Electric Expectations – What to Expect from a Bike Friday Electric Assist System (BF EAS)


Design Goals At Bike Friday we start with the end goal in mind. Bicycles are already so special and refined it makes no sense to add things that do not add to or enhance the wonderful experience of cycling. We usually think of cycling as self-powered, so efficiency takes more thought than when designing powered things. Since electric assist is adding power the handling of this needs to be very careful so as not to destroy the magic and joy of the cycling experience. Our list of requirements is lightweight, quiet, unobtrusive to our cycling skills and to those around us also cycling. To make it better. The goal then is to make it possible for any cyclist to ride as a strong cyclist without a major downside.

Do you need an assist? – Ask your average capable cyclist and they will tell you, they do not need a motor. For over 40 years of my 50+ years of cycling, I would have said that also. Turns out it was because I was human, selfish, and ignorant. I was a strong cyclist. Being strong I have come to understand is to be able to ride at 15 to 17 mph without undue effort for an hour or two at a time. (24 to 27 kilometers per hour) The kind of speeds you would see on Cycle Oregon by those finishing each day in the middle of the finish times. (40 to 90 miles a day) This I found was my preferred commute speed also. For me that range optimizes travel time, cooling effect, ability to ride & talk with others & the safest speed with others on shared routes. (Bikeways to appropriate roads with light car traffic.) Turns out one of the most cycling experienced areas of the world also agrees. European electric assist laws allow motor assist to 25 kilometers per hour. If above that you must supply the power yourself. Or get licensed and insurance!

How much pedal assist is needed? – This can be pretty simple. The best way to measure human power is in watts. Average Humans on a bicycle are producing in the range of about 50-150 watts for 1 to 8 hrs. Tour de France heroes are not average. They can support from 200 to 300+ watts for many hours. They are working really hard to do so! Those 20-30 second 40 mph sprints at the end of the stages? About 1000 watts. World hour record, about 400 watts! Aerodynamics plays a huge role in your speed at 20 to 40 mph. The hour record was about 30 miles! The faster you go the more your power goes to the wind. Your important number.

How fast can you comfortably ride? That is your personal optimal wattage. Here is how to find that. Based on a 150 lb rider, on a well-fitting lightweight bike, with good tires on flat pavement. Can you ride 9-11 mph? You produce about 30-50 watts. That is 3 times faster than walking, making you the most efficient mover on the planet! 11-13mph? You produce 50-75 watts. 13-15 mph>75-100 watts. 15-17mph>100-125 watts. 16-18mph>125-150 watts. 18-20mph.>You are putting out about 150-200 watts, & for regular riding probably do not need an assist. But if the friends you regularly ride with do ride this fast &regularly drop you, some assist might enhance your experience as it is more enjoyable to be able to keep up. If people you ride with have trouble keeping up then some lightweight assist might be good for them! How about your spouse? Sound familiar?

So what does a Bike Friday Assist System look like? – Researching electric assist and electric bicycles can be quite confusing. A Bike Friday systems’ #1 goal is to get you into the 125-watt range or to the 25kph (15.5mph) speed if you are pulling a trailer, heavily loaded, or on a cargo bike with kids, or special hills and challenges on a route you struggle with.

That means you may need an extra assist of 25 to 100 watts plus the potential of maybe another 75watts in some conditions. Online research will see suggestions of 750-1000 watts needed. And many folks say you need a throttle. A throttle & over 500 watts means an electric motorbike! At best you would be assisting the motor. More likely your 50 watts are irrelevant & no need to pedal at all! Motors and batteries to achieve 1000 watts are large and heavy. Motors and batteries for Bike Friday assists are small & light. Adding typically only 10-11 lbs (5kilo) to your bike. On a typical Bike Friday assist, you can easily remove the wheel with the motor and put in a standard wheel when the assist is not needed or wanted. Same with the battery. Easy to take off when not wanted. There is no throttle in sight. In fact, no controls really. The system needs to be turned on like turning on a bike computer.

Your regular bike skills do everything else. When you start to pedal, the BF EAS adds the necessary watts you need to get to your goal. It does this while it seems to you that you are doing it. You are just feeling especially good today and strong! A Bike Friday with assist is typically well under 40 lbs and can be under 30 lbs. Typical Electric bicycles are over 50lbs. Even very expensive so-called light ones are in the 40s. The lightweight means they ride well even when the power is not on. It means they are lift-able. It means they are more useful and fun and easier to take with you.

In addition to being light & quiet, BF EAS is designed to be legal. – Most of the world where electric assist is popular have specific laws for them to be on the road as a bicycle rather than a motor vehicle. The core restraint is 25 kph maximum speed with an assist. Not surprising to find it is in my sweet spot above. Some laws talk about different wattage limits. Higher wattages can accelerate faster but the speed limits are usually similar. In the US we still have areas with no law, or they are illegal, or the laws have 20mph, 28mph, and 750-watt limits. Still the wild west. None of these will be problems for the BF EAS because its intention is just to assist you to be a strong cyclist and to be able to travel. One of the most difficult legal restraints for electric assist is traveling by air with them. The problem here is batteries and flight safety. Bike Friday systems are all available with airline legal certified batteries! And many packed Bike Fridays with assist will fit within the 50 lb weight limits for a minimal or free check on.

Control System

Design is personal. – why the use of an assist might be relevant for you. I have been a bicycle commuter, a sport rider, and a tourist most of my adult life. Cycling was core in raising my children, both in pulling them in a trailer and riding with them in tandem. I feel their confidence as adults and their connection with me has been much enhanced by raising them close to the concept of personal power that cycling has at its core. There are times looking back where a little assist would have made it so much better or have been essential if I was not such a strong cyclist. No wonder more haven’t found that child raising magic.  But they could with an assist!

A couple of years ago I started having issues with hips and a leg and for a time I wondered if I would need to give up cycling to work and give up my core exercise and social/ fitness outlet. I lucked out and was able to find the wonderful secret that appropriate assist was for me. What it has allowed me to do is continue to ride to work and back on a predictable schedule. Sometimes pulling a trailer that I need to get things from my home shop and back from Bike Friday Central. Some days I am better than others. The BF EAS allows me to dial in 25 watts or 100 watts or 150 watts. Whatever I need that day based on how I feel, how much I am carrying, & whatever the conditions. Because I can, I actually ride more & make more trips than I used to do, because I can add a bit of assist to bring me to that normal joyous sweet spot. My design is personal & I want the best for you also.

Best in Cycling,

Alan Scholz

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