Skarper E-Bike Conversion Kit Simplifies Electrifying Your Bike

If you’re a Hackaday reader, it’s a good bet you could figure out how to convert your bike to use an electric motor. But you might have more important things to do, so a start up company, Skarper, wants to help you with a conversion kit and the folks over at [autoevolution] took a closer look at how it works. The interesting part is that it transfers power from the motor to your wheels through a disc that substitutes for the bike’s disc brake. You can see a promotional video about the product from the company below.

Unlike some conversions, it looks like with this kit you can easily snap the assembly on the bike when you want it powered and take it off when you want it to function normally or if you want to take the electronic part inside with you.

The company claims that the 250-watt motor can to propel a bike to nearly 20 miles per hour. But we’re willing to bet you can’t go that fast and get the claimed 37-mile range. On the plus side, a 30-minute charge will net you another 12 miles and a full charge only takes 2.5 hours. The battery and motor weigh a bit more than 7 pounds. Obviously, you’ll need a bike that has disc brakes.

Cost? About $1,200, so it isn’t quite an impulse buy. Especially if you have the time and wherewithal to roll your own solution. For example, try a skateboard motor. Makes it easier, too, if you have a 3D printer.

65 thoughts on “Skarper E-Bike Conversion Kit Simplifies Electrifying Your Bike

  1. “The interesting part is that it transfers power from the motor to your wheels through a disc that substitutes for the bike’s disc brake.”

    This is the piece of information one is expected to to extract from this article and the product. A disc power transfer which is uncommon on ebikes.

    1. One reason this beats hub conversions is that it couples the reactive torque into the frame, rather than trying to rely on having a weird tight-fitting squared off axle jammed into the dropouts and trying to lever them open. The last conversion I did, we had to grind the dropouts deeper to fit the axle because it was significantly deeper than a stock 10mm threaded rear axle. I also like that because this uses the disc brake edge, which is 160 or 180mm, you get inherent gear reduction that hubmotors have to do with heavy planetary gearsets to get the motor RPM up high enough to start producing real power.

      1. Higher powered hub motors do exactly what this unit does. The have an arm that attaches forward on the frame. But not with nylon pull ties like this ‘cute’ little motor. At 250W I doubt it needs it, except it’s bodged on so badly.

        The main problem with most hub motors is the terrible Walmart grade wheel they come with. Smart move is to buy them bare and just rebuild a wheel around them.

        Electric motors have great torque, don’t want to run them stalled for long or they’ll burn, but anything with decent power will get you going in no time.

        Not all hub motors have gears, only the lame ones. Get someone outside the EU to order it for you and ship it. Rules are just suggestions.

        Get a snell helmet. Eggshells pass DOT.

        1. SNELL historically hasn’t been the best, at least for motorcycle helmets. While typically indicative of higher quality, its dual-impact methodology leads to overly-stiff foam, which decreases energy absorption in realistic impacts. Not sure how it is in bicycle helmets.

          It’s been a while since I’ve bought a helmet, but I know that at least for moto helmets, European standards were a much better indication of how one’s head would be cosseted in a crash.

        2. From what i read this is not intended for speed but to assist in comute travels but the price tag is an absurd for such simplified tool. The concept of the power transfer is similar to motorcycle gear discs.

    1. To clarify, Menno is probably talking about the Netherlands as his name is Dutch. We have a lot of bikes here and most common are brake pads, or internal brakes inside the wheel, not disk brakes.

  2. Whenever I see an article about an E-bike, especially an E-bike conversion, I want to rush to my keyboard and pour out all the bad language I have ever learned. The bicycle is perhaps one of the worlds most perfect inventions. Converting it to use a motor is an incredible monument to the laziness and stupidity (did I mention laziness?) of modern man. Just pedal the thing! Get some exercise and work off those ugly pounds. No wonder there is what some call an epidemic of obesity. If you are going to put a motor on it, go the whole route and use a gas burning 2 stroke with worn rings that belches out clouds of black smoke and makes all kinds of racket.

    I restrained myself. You’re welcome.

    1. There are use cases for both manual and electric bikes. I normally commute on a manual CitiBike for the exercise. When I’m in a hurry, I choose an electric CitiBike.

      If it takes an e-bike to get someone out of their car (or out of their house), I think that’s a plus.

      1. Absolutely agree. I have rheumatoid arthritis at a pretty young age, I was always athletic but healthy. Now my body has gone through muscle wasting and my joints… Fugetaboutit. My physical therapist suggested an ebike and I never looked back, I rarely use my own car now and the extra sunlight wis a bonus! Health is noticeably improving.

        1. I to have a few health issues and the most difficult is the deterioration of the bone, muscle and nerve commonly referred to as CMT and before the ebike I was almost completely homebound and was in the worst case of depression and anger but I found out about the electric bicycle and I purchased one and it has totally changed my life for the best and people who like to judge others and don’t even know what the situation is are basically big headed hypocrites and should really find a way to understand that they have absolutely no rights to judge others and keep their arrogance on silent mode so nobody has to hear the nonsense.

    2. Best not to judge before knowing how it’s used.

      I wouldn’t want to replace my bike which only gets used for fun with an e-bike for exactly the reason you wrote. It would defeat the purpose.

      OTOH, if I had a lot of coworkers biking on their lunch breaks or if I was in a big city somewhere that bicycles were commonly used for errands then by mid-afternoon I can imagine e-bikes could deliver an appreciable reduction in office BO.

      I did once work in an office with an excercise room and showers. If you brought a bike and were fast you could get in some excercise on lunch break and then shower up before returning to the cube. That was pretty nice. The actual job… not so much… so I moved on.

    3. Instead of thinking about Ebikes as replacements for standard bikes, think of them as a replacement for commuting by car. Some people work 20-30 miles away and are never going to bike that distance every day whereas an Ebike might make it doable. Many ppl with mild physical disabilities who otherwise might not bike at all can do so with an Ebike. People going to the store and carrying lots of cargo might only be able to lug it home, especially with uphills with E assist. Sometimes even while towing kids! Bikes are great and of course it’s better for the environment and for getting exercise to go without electric, but Ebikes have their place. It’s not a threat to the standard bike, calm down lol

      1. What does a standard bike do? I’m Dutch. I almost never use it for fun as I am not particularly fond of biking; I use it almost exclusively for commute.

        I live 21 km from my workplace, so each day [that I don’t work from home], I bike 3 km to the train station and take the train. I occasionally take the bike to work but that takes quite a while. I would bike (almost) everyday to work if I had an ebike.

        1. I really really wish my commute had the infrastructure for a safe bike trip. There is no question in my mind that there would be a bike-car/truck collision in my future if I commuted to work on a bike. I think most places in the US are the same. It really is a shame.

    4. I also restrained myself. I wanted to make a smart-ass retort to your comment, but I will try to be a bit more empathic.

      Ebikes are *very* useful. Both me and my wife ride e-bikes daily. Neither of us are overweight. We’ve moved away from the city last year and we need to ride at least 5km somewhat downhill to get (almost) anywhere useful. Obviously it’s 5km uphill to get back. It’s not a big challenge, but it gets boring and tiring really quick, especially carrying any kind of load (every and every day).

      Have I mentioned that we don’t have a car?

      You can go around calling people lazy, but maybe relax a little and try to imagine that people have various life circumstances. Am I lazy to bring groceries home on an e-bike instead of riding a bus? Is my wife lazy because she takes our daughter to pre-school on an ebike instead of having her walk all the way on foot, or taking a bus? Or should we buy a car instead?

    5. Simple minded narrow perspective. Not being able to formulate an intelligent opinion based on factors that are not only true for you but also and additionally true to others. You do you, leave others to do their thing and the world is a better place.

    6. Yikes. Must be nice living in an area that is flat to be able to get an opinion like that.

      I e-biked 12 miles to work and back for years. About 9 of those miles along a train track turned bike trail. I wouldn’t want or need a motor for that most days. On the way there, I would be fighting directly against the wind most days. On the way home, the 400 foot climb over 1/2 mile at the start of the ride and 200 foot climb over 1/4 mile at the end destroyed me, even with the assistive electric motor.

      Nothing like working to the bone all day and then watching the sky go dark and start raining 10 minutes before you leave for the day and having to make that freaking monster climb out of the river valley.

    7. Severe Tire Damage has Severe Myopia. I live in a rural area of Colorado. I own a Yeti FS, a Specialized Crux, a Specialized Roubaix, and a Townie. I like them all. They have different uses. But I also have a Trek hardtail that I converted to an e-bike myself (Bafang kit). The other bikes are for pleasure and exercise. Weather permitting, the ebike allows me to keep my truck in the garage, and run my errands in steep terrain and stiff wind without needing a shower the moment I get off the bike. Severe Tire Damage: If you don’t want an ebike, don’t get one. But suggesting people like me need to lose weight and exercise is really insulting, and my case, just plain wrong.

    8. I’m certain the vast majority of e-bike converters are neither fat nor lazy. As for gas conversion and other unpalatable options, I’d give the puritan bicyclist in you a rest

    9. Rather thoughtless comment, STD, one that demonstrates your lack of familiarity with how many people use e-bikes. I have two bikes. I ride my road bike 100kms or so for pleasure, and I saddle up my electric assist with panniers and packsack and ride to market to do my shop. I also put the motor on regeneration mode and charge the battery when I feel like getting *more* exercise. If you think riding a 42lb bike with 30lbs of groceries is “lazy and stupid” I don’t know what to say. Just getting out on a bike is a win for a lot of people, and yea, for many just pedalling any bike is exercise they wouldn’t otherwise get, not that that is any of your business. Snobby attitudes aren’t helpful.

    10. You suck. Judge before knowing. I have degenerative back disease, six herniated, disks three fused disks, 4 bulging disc’s,knee surgery’s and scoliosis. I could not ride a regular bike without extreme pain. With my “E-BIKE” I have been able to gradually use more and more of my own effort and get out to enjoy the scenery at the same time. Not every one can just hop on a bike and ride for miles when they haven’t had the chance to in years, well except for STD HIMSELF.


    11. Your logic is flawed. I have used and sold ebikes for 12 years and what they do is simply expand your range beyond what a person could reasonably cycle. If you could only cycle 10 miles you now can cycle 15-20 meaning it gives people another alterntive to commuting without cars and petrol. It gives older people or disabled people the ability to enjoy a pastime they couldn’t enjoy before and most of all it gets ‘lazy’ people off their backsides and into cycling. Fresh air, exersise as you still have to peddle but not be so worried about hills.

    12. Extremely ignorant comment. I and many others who have not ridden a bike for many years are once again riding. I have a bad knee(6 knee surgeries), lower back issues(thankfully no surgeries)and the power assist and throttle have allowed me to ride again. Presently I’m building strength, stamina & working on coordination.

      I restrained myself. You’re welcome.

      P.S. You’re still ignorant

    13. A parody perhaps? 1 less car starts with 1 less car journey. And it’s probably best to start with something physical before doing something physically challenging. Personally I think all cars should be fitted with a pedalec system ie feet have to be turning for the engine to work. But this will do for now. The concept is elegant and adaptable. Eg FWD, Cargo, Trailer, Multitrack, All ability. It is a lot money for a neat way to power bike with cordless angle grinder(?).

  3. If you’re anywhere near one of those cities that had the bike share company disappear I’m guessing motor parts will be available shockingly cheap. At least I’d hope so… be a shame if all those ride share bikes became e-waste.

    1. They did, there are pics and videos of all those lime bikes just piled up at the dump… Just gotta talk to the dump worker, and go strip them down for free rather than pay for the parts lol…

  4. Looking more closely, it appears that the actual motor is within the disc brake. If you look at the pictures from the linked article, and then examine the back of the battery unit at 0:53 within the video, it’s clear that there’s no mechanical transfer from the outboard unit to the disc. The attachment points may provide electrical contacts.

    As long as there’s a way to attach this motor to your wheel, your bike probably doesn’t need to actually have disc brakes.

    1. Looking at some pictures, maybe the magnets are on the disc, so the coils might be in the clip-on unit. Interestingly, if that is what’s happening, there look to only be 2 magnets covering 2/3 of the round, so it would be an intermittent drive.

    2. He says it has a pinion in it in the Eurobike video. You will notice a round hole between the two keyholes.
      So I am guessing that inside the disc adaptor it has a ring gear, and a pinion behind the plastic cover, and something like a square drive from the box to the centre hole of the pinion.
      The pinion would have a bunch of side thrust so you would need large diameter bearings, or possibly use a planetary gear or bearing arrangement only driving a single pinion.
      There’s not so much space when you consider the disc centre lock nut, or the 6 bolt holes.
      Keeping lubrication on that gear, dirt and water out, and not getting grease/oil leaking onto the disc, might be issues.
      Seal drag might only be when the motor is attached. When detached the whole assy rotates with the disc, so no drag in pedal only use.
      I looked at a similar idea at the front chain ring, where the pedal torque sensor and final drive planetary are permanently attached to the bike, and the motor,batt,elx detach.

  5. The “hack” part is when I find one of these unattended and get to cannibalize it for parts… Nah. Wouldn’t do that to a fellow cyclist. Not when there’s hundreds of scooters down in the gulch, ripe for harvest.

  6. To roll my own solution? Not likely with the strict legal requirements for control. The electronics are easy. Their DynaClimb is supposed to only help when actively pedaling in the legal range, but their explanation about a “host of wireless sensors” to do so makes me wonder.

  7. Many buy an ebike and think they will get exercise but become seduced by the ease of just using the throttle. I have to say that is so tempting at times. But with 9 levels of PAS on my bike, I hardly ever go past level 3. At that level I no longer need to plan my rides to avoid hills, of which there are many around my area. I still get one hell of a workout but now my 71 year old body doesn’t have to come close to having a heart attack on the endless climbs. A thirty something year old told me I was cheating as he passed me on his ultra light carbon framed two wheeler. Perhaps, but better to be out and about on an ebike than to be sitting in front of the TV.

  8. its not at obvious as other ebikes cons. but at that price id be more paranoid its just gonna burn out in under 100 hours.

    but if you cant turn off the pas and use manual control; thats crap. so….

  9. I ebiked to work for 6 years. 14miles each way. I was 67 yrs old when I changed jobs and started working from home. Now I ride my old road bike non powered 14 miles every morning before work because I enjoy it. I am getting close to 70 and will ride till I die.

  10. If im still having to pedal then its not fully electric. Amd thats not worth 1200 when i can get a fully electric scooter thats compact now days for just a few $$ more. I dont have to carry my ride with ne ill chain it up.

Leave a Reply

Please be kind and respectful to help make the comments section excellent. (Comment Policy)

This site uses Akismet to reduce spam. Learn how your comment data is processed.