hilly terrain

Regenerative Brakes on Ebikes

April 20, 2013

Regenerative braking is very common on electric cars, and rare on electric bikes. Regen means that the electric motor is used to slow you down when stopping and generating electricity which is fed  back into the battery pack which increases your efficiency and increases range. That is how a Prius is able to get almost as good of gas mileage in stop and go traffic around town as it does on the highway.  Obviously, the regen braking system offered on electric bikes is much less sophisticated than the ones offered on electric cars. Ebike regen is usually just on or off and has mild stopping power and is used in addition to manual brakes. Usually on an ebike regen happens when you softly apply pressure on the brake handle and you feel the regen brake kick in….compress the brake handle more and the regular brake activates. Variable regen for an ebike where you have variable amounts of regen based on how hard you hit the brake handle does not exist as of this writing.

Regenerative Braking and Efficiency

The efficiency gain of your regen system will largely be dependent on how hilly your riding environment is, and the style in which you ride.  Basically:  how often do you stop-and-go and how hard do you stop? Regen can add anywhere from 5-20% efficiency but average rider on the average terrain will get  about 10% further distance per battery charge.

What about drag?

Regenerative brakes on an ebike create a bit of extra drag, even when not using the brake. This is because the motor is always engaged in an ebike with  a regen system, so the motor is always turning even when coasting.  This drag is so small its imperceptible when riding. However it does cut down a small bit on the efficiency of the bike.  However, the positive effect on efficiency of a regen system, greatly outweighs the small negative effect created by this drag.


Regenerative Braking and Brake Wear

Regenerative braking can drastically reduce your brake wear and also keep your brakes from getting to hot on extended down hills. Also regen never squeaks and has a nice smooth feel to it. Its a nice and  liberating  feeling to be charging your battery while riding, rather than creating friction and heat with traditional brakes.


Which bikes are capable of adding Regen?

The easiest motor set up to add regen too would be a gearless hub motor. Geared hub motors have freewheels and therefore cannot have regen. Mid drives could possibly have regen but its harder to implement.

How easy is for a manufacturer to provide regenerative brakes?

classic cruiser

None of the Pedego gearless hub powered bikes have regen…what a shame

On a gearless hub motor very easy. Its suprising that manufactures such as Pedego that sale their best selling bikes with direct drive hub motors have not implemented regen.  You would think it is expensive and complicated but it is not. It would literally costs these companies less than $10 to implement it, by just changing to a slightly more expensive controller.

How is Regenerative braking implemented?

It is a simple circuit inside an ebike controller. Since the controller on a production bike already has wiring going to the ebrake (all production electric bikes must have an ebrake cut off), it requires no additional outside wires.

Which production electric bikes have regen braking?

With most modern production bikes choosing small geared motors, regen on a production bikes has been  rare. The big exception to this is any Bionx powered production ebikes (Ohm, Smart, Grace, Trek, etc)

Although it is very easy for any electric bike with a gearless hub motor to have regen braking, only a few companies have implemented it. However most of the high end bikes with direct drive hub motors have implemented it such as:

stromer st1

The Stromer St1 has regen brakes and Magura Hydraulic Brakes…sweetness


The Smart bike with its Bionx motor has regen



Speciailized Turbo has Regen


The Stealth Bomber has Regen




Grace electric bikes have Regen


Ohm bikes have Regen


What if i want to build my own electric bike with Regen?



It is easy. Just be sure you buy a direct drive hub motor such as the Crystallyte or 9c hub motor, and make sure the controller you buy has regen ability. The easiest way to build a bike with regen is invest in the Bionx kit (read review) which comes stock with regen.

 What about variable Regen?


Variable regen is a real sweet spot for an electric bike and is not available yet. Ebike regen is usually a  simple on or off.

The one exception to this is the Bionx kit which you can control the amount of variable regen on the dashboard if going down an extended hill.  In the above photo you can see four bars of pedal assist, and if you hit the minus key on the dashboard, you can get 4 levels of regen. Pretty sweet.  Bionx seems one step away from adding this to the brake lever where you can get different levels of regen depending on how hard you apply the brake.  Kudos to Bionx for having the best regen system available for electric bikes.

Here is a video of how the Bionx variable regen works:


 Technical testing information about Regenerative Braking

Justin Lemire Elmore, one of the worlds leading ebike engineers, did a great technical test piece on regenerative braking.   You can read his findings regarding regen on this thread on endless-sphere.


justin lemire elmore



Eric has been involved in the electric bike industry since 2002 when he started a 6000 square foot brick and mortar Electric Bike store in downtown San Francisco. He is a true believer that small electric vehicles can change the way we operate and the way we think.

  • http://www.PTVshow.com/ PTVshow.com

    Thanks for the explanation of regen braking. I’m not a big fan of regenerative brakes on bikes. They work well on cars due to the weight of the car and the amount of braking most car drivers do. Bicyclists don’t have the weight factor, plus they do far less braking for numerous reasons.
    The added drag factor, no matter how small, makes the benefits of bicycle regen braking a wash, at best.
    As always, your blog-post was awesome, but I’m not a regenerative braking convert.

    • ElectricBIke

      That’s ok :) not everyone has to believe. Take a look at this link and read through the thread if you have a chance: http://endless-sphere.com/forums/viewtopic.php?f=2&t=7891

      • juner

        i m using magic pie2 front hub motor . Regen braking good when braking softly you can brake without using brake pads either on flats or going down long steep hills . as generator this type of motor on battery plugs gives approximately as much Volts as your speed (rim is 700C) .On 48 V system may be not significant difference on distance per charge . but on 36 or 24 it may could a bit charge battery when going downhills .

  • http://www.facebook.com/dondico Don DiCostanzo

    All of our research and development support the opinion that regeneration is not effective on an electric bike. We believe that the amount of energy captured by even the best of systems is irrelevant to extending range. Claims of it by manufacturers is purely hype and I would question the integrity of those that make the claim.

    • ElectricBIke

      Don (owner of pedego) thank you for checking in. Regenerative braking is not hype…it is used on other high end electric bikes which use direct drive hub motors such as the Stromer St1, all bionx bikes and the Specialized Turbo. I really encourage you to read the testings and findings done by Justin in this thread http://endless-sphere.com/forums/viewtopic.php?f=2&t=7891. Interestingly in that thread he says that the negative stigma of regen was created by the manufacturers who do not offer regen. I am not saying this is you at all…but i think regen would be a great addition to your Interceptor and Comfort Cruiser lines. Seriously read that post and consider it. And please dont call me “Pete”. 😉


    • Joe Blow

      It’s not hype but rather a mathematical certainty. The kinetic energy you (or the battery) expend to get up the hill gets converted to potential energy at the top of each hill that can can be harnessed going back down the hill. The only thing that comes into question is the efficiency of each component used to harness the potential energy. Hilly terrain offers the greatest efficiencies, assuming you make it to the top.

    • http://www.electroportal.coom sun-energy

      I tend to agree with Arizona. With a high speed car or motorcycle using large batteries more able to absorb high amperage from regen it makes far more sense than what smaller e-bike cells are able to handle without overheating. Heat is the battery cell killer…especially cells that don’t have proper cooling jacket and heat (or cool) unevenly. Using lithium is technically more challenging than lead acid also, due to the need for sophisticated BMS that’s also got to prevent shorts.
      Put another way, 12Ah lead acid battery shouldn’t be charged with more than 3A unless you’re

  • http://www.facebook.com/SidewalkAstronomer Brad Sloan

    Thanks but no thanks I will take my freewheeling geared hub over regen any day. I bet the amount of battery charge saved by being able to coast freely is greater than regen to the battery for total range of the battery. Also here is another opinion on regen.


    • http://www.facebook.com/SidewalkAstronomer Brad Sloan

      I reread both articles both talk about 10% regen. I would like to have seen a graph line show the charge level of the battery before and after regen. If 10% regen only equates into .7 miles extra miles it sounda more like tech overkill and a sales gimmick to justify the high price on some of these bikes that use it. I have seen Justin’s videos before about motors and water. Long video, but low on useful information other than don’t let your motor get wet. Face it we are not reinventing the electric motor here. Electric motors have been around for a long time. Most of this has already been figured out. Also what is telling is Justin’s bike ODK 2 that he designed has no regen because it uses a geared hub.

    • Joe Blow

      That article assumes you are riding in Saskatchewan. If I use the 75 stops x ~15 seconds/stop, that equates to about 20 minutes of equivalent downhill braking while draining the battery going uphill. Regenerative braking will provide significant gains on undulating terrain, particularly if slighter grades are manually pedalled uphill.

  • hcrider

    Falco offers 5 levels of assist and 5 levels of regen, variable regen on braking, and regen that kicks in to keep speed from topping 20 mph on U.S. models. By pedaling down hills at 20 mph or more in rolling terrain, I do see the voltage drop staved off and the range extended on my Trek 7300 with a Falco 500 watt motor, running a 36 volt,
    11.6 ah battery.

  • DaveD

    I really only care about smoothing out the hills – to have a system that will save my brakes on the downhill and get me up the next hill. I don’t care about riding faster or plugging in to ride with less effort. Has anyone optimized a system to do this?

  • ReVolt

    To the folks who take the position that Regen is useless or miniscule on an electric bike I say, Get your facts or get some experience. I am looking for a replacement for my BIONX PL350 which has rolled the odometer over two times (>13,000 miles). The batteries are still going strong with over 500 charge cycles and range more than 30 miles with me pedaling and the thumb throttle full bore at 20mph. The only reason I need to replace it is the Hub aluminum case broke out the center where the freewheel screws on. If you ride hard and need to slow down the way I do then you will need aggresive braking which the PL350 has. Four levels of regen braking to be precise. I test rode a Stromer and be aware that there in no regen braking on the Stromer while the battery State of Charge (SOC) is above 50% what’s with that? The Stromer designers have not figured out how to regulate DC Buss voltage. I would have bought a Stromer if I had not discovered that on a test ride. Sadly none of the E-Bike manufacturers have been able to do this. Yeah right, if you listen to tha “Also Rans” they pooh pooh the idea. Too bad they don’t waste the few bucks it would cost them to implement regen. On a brushless synchronous motor the hardware required is minimal. I think the detractors are just not smart enough to manage the technical part of implementing Q4 motor operation.
    Regen makes a difference. Get over it folks. Electric cars would never be without it. Someone said “What about the Huge Amps that might kill your battery while regening?” Come on people I suppose those Huge amps are insignificant out one side of your mouth and mega destructive out the other side of your mouth.
    Too bad BionX is the only one out there that can do this. I keep looking.
    Someone please educate me about why it is preferable to turn up your nose to this technology and shun Regen braking.
    Or Else if you see any other companies finally getting it together let me know who they are.

    Cheers, Rich

  • Shaun Dobbie

    The vast majority of electric bikes with direct drive hubs actually have regen. You just have to be going faster than the motor can go at the current battery voltage. The freewheel diodes in the mosfets rectify the power to DC back into the battery but you usually won’t notice it unless you are going really fast down a hill and have a voltage readout.

  • bobolicious1

    I bought my first E-bike in 2007 and it was PAT, it had 5 modes of pedal assist 750 wat motor and also had regen brakes. I have nothing bad to say about the regen because i NEVER noticed it lol, but it has been around for long time now. At least 8 years. It’s nothing new but for a bicycle like others stated its not enough to notice or even care about. With the 90 + volt batteries and over 100+ mile range i find it hard to believe anyone is gonna notice or care about saving 1 mile on regen if that.