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Turn any bicycle electric (dhruvvidyut.co.in)
350 points by samdung 1 day ago | hide | past | favorite | 195 comments





I love everything about the demo video on the homepage. It's always fun to see a creator beat up their product and see it withstand the abuse.

As far as "any bike can be an ebike" I'm surprised that Hilltoppers[0] haven't gained more traction over the years. You just pop off your current bike's front wheel and install theirs.

[0] https://hilltopperbikes.com/product-category/electric-bike-k...


You just pop off your current bike's front wheel and install theirs...

And then you remove your bottle cage to install their battery (hope you don't ride a small frame). And then you install the speed/cadence sensor. Then you install the display/swtich/throttle assembly. Then you wire it all up.

And then you get into all the compatibility problems - many e-bike conversion kits are sold with a freehub that's not the correct size for modern cassettes (comes with HG 9-speed, need an HG 11-speed, XD, XDR, or Microspline freehub). Axle widths and axle type (bolt, QR, thru-axle).

Granted, all the above is easier than it sounds, but it's not quite as simple as "swap wheel, done". You need a working knowledge of bicycles to do this.

Then there's the cost. Basic "unbranded" kits are $500 or so. Brand-name kits, larger battery, or mid-drive kits cost more. Is it worth putting a $500 kit on an old bike that's only worth $100? Or, are you better off buying a new bike with warranty and no need for service for years (which will cost $1500-$3000).


> And then you get into all the compatibility problems - many e-bike conversion kits are sold with a freehub that's not the correct size for modern cassettes (comes with HG 9-speed, need an HG 11-speed, XD, XDR, or Microspline freehub). Axle widths and axle type (bolt, QR, thru-axle).

To be fair, all of these problems exist when doing work on normal bikes too.


Yeah, I got so fed up with all that BS I just completely stopped riding bikes and went 100% longboard instead. They are so robust, simple and predictable.

I own bikes and a longboard and the later is not really a replacement for the former anyway.

You see a lot of skaters carrying their skate in a bikepack by bike to the skatepark. Surely if skating is their passion and the longboard would be a perfect medium/longer distance solution they would use one to carry their smaller skateboard to the skatepark. Yet you never see that.


Of course it depends on your commute and the quality of the pavement where you live. Right now I'm blessed with smooth asphalt pavement and a nice gentle slope most of the way to work, and then I can skate flat + walk a steep hill going home.

Previously I lived in London and commuted by longboard there as well. Obviously flat but the surface quality of the pavement was a lot worse, so my knees did complain more.


Doesn't that just shift the increased maintenance burden to your body?

My body tolerates water and mechanical stress significantly better than whatever poor excuse for metallurgy is coming out of Shimano these days. Apart from enshittification and MBA bullshit, there is absolutely no reason they can't make a bottom bracket last twenty years.

Not to mention the fact that the last place you want to add a bunch of mass is the front wheel of a bicycle.

I don't think it's that big a deal outside racing applications.

Is the entirely correct? When there is side wind, a big guy on deep wheels sure has an easier time than a little guy on deep wheels.

The amount of braking you can apply before flying over the handlebars decreases significantly the more you move the center of gravity forward.

People who can ride shift their entire body back when emergency braking, which is much more significant than some added weight on the front wheel.

People who can't ride usually don't go OTB because of the torque around the front wheel (i.e. the entire bike rotating), they go OTB because they can't handle (or aren't ready for) the sheer force of the deceleration, it makes their hands fold.


> hope you don't ride a small frame

That bike bottles are so small seems to be due to small frames. 750ml is about the max normal size. I’ve tracked down some 950ml ones, but I’m sure you could go larger with a decent sized frame.


They make 1L bottles, but that’s larger than normal and probably special order.

Most of the batteries for e-bike kits look to be at least the size of a 1L bottle, if not even larger.


Or a used one. I mean if part of the bikes old anyway. I got a used one for ~$250 though I've since spent $100+ fixing stuff.

Cassette compatibility isn't going to be a problem with a front wheel conversion kit.

Fair, though you still have axle standards to consider. If it's a QR bike, it's pretty straightforward. But, most new bikes (in the US) are through-axle and disc brake.

Yes.

Well said. And then... even after all that, it's probably not legal, and no insurance company will insure the bike or you if you get into an accident.

I’m sure if I get hurt on my bike, my medical insurance coverage will not care at all whether the injury is from riding an e-bike.

If I hit somebody else on my bike… I don’t think I have insurance for that liability? I don’t think my auto or homeowner’s insurance policy mentions me riding bikes at all, let alone an exclusion for DIY e-bikes.


Often, in the US, your normal home-owners/renters policy has some level of umbrella liability coverage. Check with your plan to be sure.

The problem is (IMO) e-bikes that are more "motorcycle" than "bicycle". Which includes a massive number of the kits.

There currently is no national framework for classifying e-bikes. There's the 3 tier system that some industry groups use, but it directly conflicts with most state's moped/motorcycle regulations.

Safe bet for an e-bike is a "class 1" bike from a major brand. 20mph cap, no throttle, the most "bicycle" of the 3.

Class 2 bikes keep the 20mph cap, but add a throttle (don't need to pedal). This probably makes it a moped or small (50cc) scooter in some states.

Class 3 removes the throttle, but bumps the top speed to 28mph. Again, this speed probably makes it a moped or scooter (or possibly even a full motorcycle).

And then there's the e-bikes that are more motorcycle than bike. 30+mph, powerful engines, and the pedals are truly vestigial. Supe73 and Surron bikes fall in this category.


US Law, i.e. Federal Law, for e-bikes is 15 U.S.C. 2085(b) and additionally Title 28 Chapter I Part 36 Subpart A § 36.105.

Pedaled vs throttle is an ablest issues; not everyone has picked up on this.


IIRC The 3-tier system is law in California. Of course, many people use more powerful bikes and there's little enforcement.

In my case (not US), home insurance cover bikes but not ebikes or escooters. For that you need a dedicated plan (<50€ per year). If I remember correctly, without that additional plan, I'm covered for my own injuries, but I'm on the hook for any injury I may cause in case of accident.

I _just_ went through this when my child had an ebike accident (AAA, southern california). You need specific ebike insurance. Auto/homeowners doesn't apply for different reasons.

Would it be different for non-e bikes?

Oddly, yes. A regular bike accident would have been covered. And it would have been covered on a moped as well even though she's too young to have a license.

Hilltoppers isn't alone in the market as well – there are no-name kits with the same target market of people who are handy with a spanner; Swytch [1] also offers kits, but their emphasis is on compatibility with the widest amount of bikes possible (i.e. they have a battery design that latches onto to tubes, racks, etc; and I'm told they provide a torque arm by default on kits so that people with used road bikes don't grind up their forks.)

[1] https://www.swytchbike.com


I installed a Swytch conversion kit on a couple of my bicycles in the U.S. I did have to file down the axles by about 1mm to get them to fit in the drops, but after that everything has been working pretty well. The ring with the magnets around the crank sometimes shifts out of alignment with the sensor, which results in the motor not kicking in sometimes. The extra weight on the front also makes it more squirrely, and I generally prefer to ride my mid-drive e-bike for distances longer than 3 or so miles.

Note that’s a front wheel not a front tire! When I first read your comment I was very curious to see how replacing just a tire could help here hah. But yeah that kind of product makes a lot of sense! I DIY’d my ebike using a BBSHD motor and an EM3EV battery. Including the bike the total cost was $3k but this type of setup could seriously replace a car in many locations, except the roads aren’t designed for it. I have plenty of experience riding bikes on public roads but I daydream about shutting down some of the roads and making them an independent bike network. The bike itself is fantastic it’s just cars that make it risky for the average person. We could absolutely accommodate more people biking if we commit to it! Would be lower costs than driving a car and I find it more fun not to be sitting in a huge metal box. My rear rack and panniers hold a lot of cargo and with good rain gear the weather doesn’t slow me down.

I have a bad habit of accidentally using "tire" and "wheel" synonymously, sorry! I updated it, thanks.

It's okay, these concepts are frequently conflated. For example when it comes to cars, it is advised to put on "winter tires", but people usually keep an entire set of 4 tires+rims so that they change the wheels instead of the tires.

To be needlessly pedantic: the wheel is the place where the non-rotating axle connects to the rotating body.

So for most automobiles, the tire (tyre) can be detached from the rim, which can be detached from the wheel hub, which encloses the wheel bearing, which is generally friction fitted to the axle (or steering knuckle/hub carrier).

Or said another way, both the tire and rim are subassemblies of the wheel, which is also constituted of a wheel bearing and hub. Some manner of brake is also generally attached to the wheel, but is not essential to the definition of a wheel.

Bicycles wheels are generally packaged along with the axle, which can be removed as one subassembly from the bike fork.

Of course the great problem with pedantry is that once you start down this road, each following step must be taken with great care. In other words, I've almost certainly said something wrong here, Muphry be praised.

What is the most technically correct definition of the "RJ45" connector that you can construct? Something something 8P8C EIA/TIA standard UTP termination something something.

https://www.researchgate.net/figure/Exploded-view-of-wheel-b...


>Muphry be praised.

Don't know whether your spelling was intentional or not, but anyway:

Muphry's law:

https://en.m.wikipedia.org/wiki/Muphry's_law

Murphy's law:

https://en.m.wikipedia.org/wiki/Murphy%27s_law

Edit: I just saw this one for the first time, after re-reading the one above:

Yhprum's law:

https://en.m.wikipedia.org/wiki/Yhprum%27s_law


Thank you so much for taking the time to explain things! By analogy from studying bicycle mechanical maintenance, I can understand that the wheel of a car has many components like you mentioned (tire, rim, bearing, hub, axle, etc.). Clearly I'm not well-versed in car terminology.

I know many people find pedantry to be viscerally repulsive, and feel that the pedant is acting self-important. I disagree with this because if you look deeper down, I think there is a reason for it: To be able to name and distinguish things. Let me give a few examples:

Some people think it's okay to abbreviate kilometres as "kms", whereas the standard is "km". By analogy, that would mean it's okay to abbreviate watts (a unit of power) as "Ws" and newtons (a unit of force) as "Ns". But now you can't distinguish them from actually useful units, like the watt-second for photographic flash output energy or newton-second for rocket impulse.

I've encountered people who call a laptop computer as a "laptop" (okay) but a desktop computer as just "computer". That makes no sense, as a laptop is a computer, and can easily be a desktop replacement especially if you attach an external monitor, keyboard, and mouse.

These days, it's common to ask "Do you want to buy the game disc or get the digital version?". But that's a misnomer because the data on the disc is digital! Ask anyone from the cassette vs. CD days about whether CD is digital music or not. Common speech ascribes qualities to digital that are not inherent in the definition. Digital does not imply electronic, high-tech, new, or immaterial; there are counterexamples to all of these. There can be digital logic made of plastic mechanical LEGO; digital signaling is as low-tech as a man writing numbers on a tablet; digital is as old as DNA (a 4-symbol code); digital information can be transmitted by physical objects like CDs or by energy like Wi-Fi radio waves.

I argue that the core qualities of "digital" are finite information and perfect copies. For example, you cannot measure the real-valued positions of every single atom in a painting, nor can you copy it perfectly. Technically, you can't copy every atom on a "digital" CD either, but by convention we all agree that the exact atoms are irrelevant and only the high-level interpretation is important. For example, no one argues that a file on a server's hard disk is any "better" than the same file transmitted over the Internet to some rando's flash drive; both files are equally good.

Pedantry means "pay attention to what these words are supposed to mean, not what you want them to mean".


> These days, it's common to ask "Do you want to buy the game disc or get the digital version?". But that's a misnomer because the data on the disc is digital!

I don't think that's really a misnomer.

You're ordering some food, do you want the combo or the sandwich? The combo has the sandwich of course, nobody is implying otherwise. But if you say "the sandwich" then you get just the sandwich wrapped up in a delivery medium.


Incredibly, some people don't have their winter tires on a second set of wheels and pay to mount and balance tires twice a year. Since a set of steel wheels can be had for 2-3x the labor of mounting and balancing tires, you're making money after perhaps as much as two years.

Needless to say, you save more money if you change the wheels over yourself. That's a 45 minute job for me, including finding the tools and putting them away.


Depends on how you value the time, space, and effort... and at those tires end-of-life, you'll need to pay for mount and balance anyway. I used to swap my wheels, but I got tired of the waste of real estate, dirtying a set of clothes, and busting my knuckles as its getting cold outside.

I have found the cheapest and most convenient solution for me is to buy high-end studless snow rated tires with a mileage warranty and run them all year.


The tires take up the same amount of space whether they're mounted or not, and if they're mounted, they aren't a trap for water and breeding ground for mosquitoes.

As for the time, I consider it an opportunity to have a look at the brakes and suspension, make sure the lug nuts are torqued appropriately, and that the wheel comes free without undue force. And it's practice for having to change a wheel at a time not of your choosing. If you're used to doing it, it's an irritation, not an emergency.

I'll admit to only having one honest-to-god pull-over-to-the side-of-the-road-and-get-out-the-jack flat tire in my life. I guess I've changed a couple for other people too though.

The rubber and tread patterns are getting more feasible for year-round running. I can't fault your choice, especially if you've done the changeover yourself in the past.


> pay to mount and balance tires twice a year

Depending on where you drive, it's a good idea to rebalance your tires on a regular basis anyway.

Incidentally, my tire shop said they've had people lose the balancing weights due to the current adhesive not being able to handle the heat this summer. Hopefully they switch to something stronger next year, but it looks like you may have to rebalance twice per summer...


No idea what prices you're referring. In Europe, the most popular car repairs franchise offers tire swap at less than 2 euro (per wheel) more than wheel swap. What steel wheel can you buy for 6 euro?

Where in Europe? Never heard of that pricing around where I live

In Germany ATU charges 22€ for tires (17"), 18€ for wheels [1]

In Italy Norauto charges 11€ for tires (17"), 10.50€ for wheels [2]

Other countries show higher differences, though.

[1] https://www.atu.de/pages/meisterwerkstatt/wartung-service/re...

[2] https://www.norauto.it/e/cambio-gomme.html?cod=PSNGOO00001IT...


I used to do this, but because I bought the tires from Discount Tire they performed the labor free each time. I thought this was great, except after a couple years the wheels inevitably got warped enough that the tires constantly leaked air.

I eventually got a whole new set of tires+wheels and the shop still swaps them for free.


Where did you live that your wheels warped from normal use? I've had alloys develop bead leaks from corrosion, but I've never warped a rim despite living in Cleveland, Boston, and now rural Vermont (unpaved roads and all).

It was from the tire shop repeatedly taking the tires on and off again over the years. They didn't sit right after doing that a few times

I'd be interested in something like the hilltoppers front wheel replacement, but the cheapest one being $550 with only 12 miles range seems like too much. The $899 specs are better, but then you're getting into deciding to maybe just buy a whole $1300 ebike instead of paying $900 for the front wheel replacement. I think if these prices were about half of what they're at they'd be selling quite well.

I don't disagree, however the 12 mile range assumes you won't pedal which of course you will. I have no investment here but I've been a happy customer. I think the ideal customer for these is someone who already has a bike and doesn't want to spend $1300 on a new ebike.

The very first time I rode a Jump bike in SF with the front wheel motor assist, I immediately ate shit and crashed as I crossed some railroad tracks. It turns out there are some downsides to having the motor in front, in this case the motor overwhelming the available grip caused the front tire to spin up, which removes your ability to steer, or indeed, keep your face off the tarmac.

Pretty sure there are zero roads in the SF ( or even in the US ) that are paved with tarmacadam.

That word does not mean what you think it means.

https://aerosavvy.com/aviation-terminology/


>Asphalt concrete (commonly called asphalt, blacktop, or pavement in North America, and tarmac or bitumen macadam in the United Kingdom and the Republic of Ireland)

https://en.wikipedia.org/wiki/Asphalt_concrete


Your own link contradicts you. See sibling comment and link for common use of the term.

The video is indeed very nice, it shows few things [1] not mentioned on the website:

- the chain is routed through the add-on device, so it should be longer than usual

- the pedals don't rotate when the chain and the wheel do, so there is a custom pedal hub with a ratchet mechanism

1. https://youtube.com/watch?v=SFsnS0Yb1Bs&t=83s


My first reaction was to just not bother when the large video appeared. Usually I hate those, so I almost closed the tab, but then I let the video roll. And I'm glad I did, it's great!

The design is pretty clever, I was expecting more work to make things happen. Also, the individual parts about mud and fireproofing etc. are quite illustrative.

However, for me the best part was the scenery. It just looks somehow... peaceful. Calm. I actually watched this several times just because of the scenery.

I don't know why it seems so peaceful. Maybe because the scenery and nature and the light (?!) reminds me of the late summers when I bicycled (not quite as effortlessly though) home as a child when the Sun was low. I mean especially the part when the dog is chasing him.

I was annoyed at one thing though: he casually throws the empty container of flammable liquid into the ditch. I hope he picked it up afterwards.


1. They're overpriced. A quick Amazon search will show comparable kits for half of the price. You can buy a whole prebuilt ebike for the same price.

2. They're dangerous. FWD ebikes have a tendency to break traction on corners.

3. They tend to destroy the dropouts in your fork.

4. Installation is much more complex than "pop off your bike's front wheel". I can't even find the axle compatibility specs on their website. You know that there are many standards for front axles, right?

Do not recommend.


Any bike can be an ebike. Not every bike can be a safe ebike. Many cheaper or older bikes have kind of crappy brakes which don't hold up well to frequent stops from high speed, especially with a heavy rider or cargo. This type of ebike conversion can be fine but know what you're getting into before you buy.

New ebikes from reputable brands come with good brakes from the factory.


ebike doesn't mean high speed.

In many countries ebike assistance is strictly limited. Sure an ebike weight more than a regular bike, but the stress in brakes is only an issue in hilly places.

If you ride a bike restricting assistance to 25kph (15mph)/like in most countries[1] and do not hit steep dow hills there are very little reason for you to go faster as going past the assistance limit feels like hitting a sudden headwind. In that case you are riding slower than most cyclists doing recreative cycling on road bikes and are less likely to need strong braking.

[1] in europe you can buy faster ones but they need to be registered like a moped (for those limited to 45kph) or motorbikes, have plates and you usually lose the right to use bicycle lanes. Having said that, a lot of people are breaking the law and never get issues until they are involved in an accident and lose insurance coverage and get fined.


I've got a 15 mph ebike used in a city center and there are lot of near misses with pedestrians stepping out in front. It wouldn't be a good idea to have poor brakes.

I have an off the shelf ebike (rad expand 5). I'd say that their stock breaks on this model are woefully under powered. I swapped them with hydraulics within the first year.

Ebikes are generally pretty heavy, even i this case where you are converting an old bike, that aluminum box of batteries is going to add a ton of weight.. and given that there are many older bikes with caliper breaks out there... that's pretty scary. At least the expand ships with disk breaks (still not up to the task but a caliper break would be totally ineffective).


The heaviest thing on a bike is the rider, generally by a pretty good margin. I've seen plenty of bikes with shitty brakes, but very few where the straw that broke the camel's back was the weight of the ebike componentry.

For most e-bikes, you're looking at maybe an extra 30lb/14kg. That's generally within the envelope of reasonable rider weights. If the combined bike and rider weight is too much for the brakes, it's probably also too much for the whole bike.

Again, not that there aren't worthless brakes in the world, but it's usually not the weight of the battery and motor that pushes a set of brakes over the edge.


A setup with a 220lbs rider on a stock "muscular bike" is still heavier and will stress bikes more than a setup with a 132lbs rider on an e-bike.

Fact is most department store bikes comes with shitty brakes, or brakes not setup by professionals (lacking cable tension, shitty stock brake pads) but the very same happen when an high end bike is badly maintained by its owner. But this is a tangential problem.

I rate Rad Power bikes as shitty department store quality bikes anyway. They are successful because they are cheap and people know they can easily bypass the set assistance limits. They are cheap because the brand spec them with the cheapest components available. It doesn't help that most bikes are delivered to the owner's door without being revised by professional and appart from googling how to change the assistance limit speed Rad Power owners are rarely knowledgeable enough in bikes to correct any setup issue.


Even when the brakes are good, the tires are thin and don't have enough traction to go from 40 to 0 in under 2 meters.. learned this lesson the hard way, but still very worth the ebike conversion.

To go with what you’re saying - my road bike runs 28mm 65-80PSI tyres. It has a patch of each tyre touching the ground which is about the size of the tip of my index finger, maybe less. Very easy to lock up.

> You just pop off your current bike's front tire and install theirs.

Nah, they're selling a complete wheel (wheelset?), which consists of: Axle, electric hub, spokes, spoke nipples, rim, inner tube, valve, valve core, tire.

(Addendum: To any downvoters, I was replying to the parent's original text as I first saw it. They made an edit after my reply, within their 2-hour window.)


What the what?! This is so cool. I love everything about the demo. No (spoken) words, just a cool functioning product, in its intended uses cases, in different situations -- on fire, soaked in water, soaked in mud.

Even if the product actually did nothing useful (which is not the case here), the video itself a great marketing copy. <3

As a product person, this excites me.

However... I'm curious. This was launched ~2 years ago (per the YT video [1]). What happened? Is this still working? How is the company doing? Any ideas?? I don't see any other videos on their channel. I see some action on their Twitter [2] but sporadic.

[1] https://www.youtube.com/watch?v=SFsnS0Yb1Bs [2] https://x.com/dhruvvidyut


The mortality rate for amazing ideas is higher in developing countries, for more reasons than incompetent or corrupt governments. For example, there are fewer networking opportunities by virtue of the network being small, or the poverty rate would put a product like this well into the disposable income/toy space.

I would bet this thing would be a mad success if the inventor had won the birthplace lottery.


Except that bicycles as everyday transport are much more common in the inventor's birthplace than in places typically thought of as "winning the birthplace lottery".



He should be the next Billy Mays

This is great.

Also interesting that they use .co.in (as in we are from "India") and their name is also very indian . As an indian I actually respect that

Vidyut means electricity in Hindi and dhruv means stars If I remember correctly.

Dhruv is a very common name in India , One of my 5th standard classmate was named dhruv , Like dhruv rathee is a youtuber.

As an indian I appreciate this project. I suppose I have seen it on the Indian shark tank as well but I am not sure!


Dhruv, rather its variation- Dhruv-ak means "constant" in mathematics in many Indian languages.

Dhruv Vidyut could be constant electricity, or Dhruv may just be the name of one of the founders or a relative of one of them.

Dhruva also means the Pole Star in many Indian languages.

It could also come from Indian mythology [0].

[0]: https://en.wikipedia.org/wiki/Dhruva


The demo video on the top of the homepage is awesome. Explains the use case, how it works, key specs and so on, all in a nice smooth video.

The acting, storyboarding, frame composition, colour contrast are all better than some movies.

i absolutely _wanted_ to watch this. And rewatch it. Showed it to others. This is awesome marketing of what looks like an amazing product, oh why isn't more marketing like this?!

Also transforms anonymous product to some specific cool inventor stuff who as you now know has a sense of humor, and actually understands product testing and target audience. Smart move, well done.

That's a quite a look, reminds me a bit of something from the Fallout universe. I'm a bit surprised at the "pedaling charges the batteries" bullet point. That's extremely rare in the e-bike world. 25,000 mph top speed seems somewhat optimistic however.

I assume it means 25 kph top speed, which is on the slower side for e-bikes.


> I assume it means 25 kph top speed, which is on the slower side for e-bikes.

This is the maximum speed for an e-bike in many European countries


slightly more nuanced, it’s the maximum speed for assistance to be classified as a pedelec.

>I'm a bit surprised at the "pedaling charges the batteries" bullet point. That's extremely rare in the e-bike world.

For the most part it doesn't make much sense for most e-bike users that have power easily available, the time required to charge a battery is a lot (average person puts out about 100-150W) and the average e-bike battery is 500Wh or so, 4+ hours to charge it by pedaling.

A normal mid-drive has clutches specifically to prevent this from happening so you don't get drag from the motor while pedaling without the motor running.

In countries where power is not as readily available it makes a lot more sense.


I would be more interested in a bike where braking charges the battery.

For commuting, every traffic light is wasted energy, and cycling on the flat doesn't need much once you're at speed. A commuter with regenerative braking could probably have a much smaller battery, making it lighter too.


A hub motor ebike can do this with the right controller, assuming the hub motor has no clutch in it.

But you don't gain much, there's not a lot of weight to slow down with an ebike so regen gives you very little back.

You do lose the ability to efficiently climb steep hills with a hub motor, and they add a ton of unsprung weight if you have rear suspension which ruins its performance, so if that's your kind of terrain they're a bad choice.

Would save on brake pads though.


> But you don't gain much, there's not a lot of weight to slow down with an ebike so regen gives you very little back.

But by the same token there's not a lot of weight to accelerate either, right? So while a moving bike has much less potential energy to recoup than a car, it needs much less to get back going again also.

So IMHO regen on a bike should be as useful as it is on a car, no?


>But by the same token there's not a lot of weight to accelerate either, right?

Right, most of the energy is used pushing air out of the way, which you don't get back from regen. Say you ride half a mile before stopping, the time to accelerate to 20mph is pretty small compared to the time you spend cruising at 20mph pushing all that air out of the way.


> Right, most of the energy is used pushing air out of the way

That's certainly the case once you're at speed (above 20km/hr is about the point where more energy is spent overcoming wind resistenace iirc). But I'm taking about taking off from the lights. Even to get you to 10 km/hr for free (or cheap) would be a bit boost for a commuter.


A friend of mine has an e-bike with regenerative braking using a rear hub motor.

It seems to have a recovery efficiency of about one third.

We once went up about 1200m in altitude difference, where it was completely empty. After having gone down again, it had recharged enough to work normally for the remaining 20km of our trip, driving in flat terrain.


> cycling on the flat doesn't need much once you're at speed

You need around 200 watt to hold 25kmph on a flat road without wind with a standard bicycle like the one in the video.

With moderate wind, it is between 350 and 400 watt.


> You need around 200 watt to hold 25kmph on a flat road

Most non-lycra cyclists I've observed seem to cruise at around 20km/hr; my personal experience is that 20km/hr is pretty easy once you're moving; 25 is a noticable bit more work. Also, for commuting where there are traffic lights involved (based on my own experience), you rarely have a chance to do more than 20, and if you do, any time advantage is killed by the next red light.


Regen braking is a thing for ebikes. I can't speak to OEM ebikes, but check out grin at ebikes.ca. They offer all the parts.

There are some cool features too like setting a speed limit after which Regen activates, so coasting down a hill will recharge you and add resistance to keep you at a safe speed.

The caveat is it doesn't make sense on mid drives because they freewheel when coasting


You might be interested in this: https://www.youtube.com/watch?v=bLu6H-K4L2Y

The video is long and the innovation is subtle, but once you understand it it's like a lightbulb moment - IMHO a really brilliant example of elegant engineering, and designed by someone who had never ridden an ebike.


This made me smile, but I looked it up anyway and it turns out it's a non-SI abbreviation for kilometres per hour.

https://en.m.wiktionary.org/wiki/kmph

Not common in my country, the UK, but maybe in India? I know the Indian language numbering system has different number groupings, so why not.


I mean, miles are so rare for non English speakers, that it didn't register to me as weird

In India, it is common to see "kmph" as an abbreviation for "kilometres per hour". "kph" is also used, of course.

25000 meters per hour would be 25 km/h...

0.25 ki-lakh-meters per hour

The correct abbreviation is "km/h", so kmph is closer to the correct one than kph. kph seems like a measure of insane acidity.

If it's about bikes it's obviously about pressure of the tires: kph means kilo-pascal hours. In other words, accumulated pressure over time.

This sounds like the opposite of my bikes, where the pressure vanishes suddenly, too often.

Am I missing something... it looks like the chainring is able to spin independently of the pedals, as if they moved the freewheel from the rear hub to the bottom bracket. Without that this would never work like he demonstrates. I've never seen the freewheel on the chainring/bottom bracket on a bike in the US, is this a common in other parts of the world?

I was very confused by that as well.

I studied the video, and the only thing that I can conclude is that he simply unbolted the pedals from the chain ring. The pedals would therefore not be doing anything at all except support the rider's feet.

The site says "pedaling recharges the battery." This would require re-bolting the pedals back on.

It's hard to see angles that can really make this clear. Maybe there are some freewheels that let the chain ring spin independently of the pedals, which makes no sense to me.


>> it looks like the chainring is able to spin independently of the pedals, as if they moved the freewheel from the rear hub to the bottom bracket

IMHO that would be a safety hazard if they removed it from the rear hub. Without that, the chain will always be moving when the bike is moving. If your pants or anything else gets caught in there it ain't stopping.

Leaving it in the back AND putting it in the front as well is probably viable if a bit redundant.


> Without that, the chain will always be moving when the bike is moving.

I have a much simpler kind of bike where this is also the case :)


It's not common but you'll see it on some trials bikes.

I was always told that that is so you can use smaller sprockets front and rear for the same ratio, giving you more bottom bracket clearance when you're hopping about the place.

Obviously that's a very specific type of bike for a very specific purpose though.


No idea how the e-bike guys here did it but Schwinn had a bike for a while (my wife owned one) where the freewheeling was in the bottom bracket, it was called "FFS". It's pretty freaky and wasn't popular. You can see it in action starting at 0:30 here:

https://www.youtube.com/watch?v=Dwpnxh_Vxpk


Shimano Front Freewheel System (FFS) for a while in the 1980s. The only bike I know of that had one was the Schwinn World Tourist. I only know about it because I found a World Tourist in the trash and rode it for many years but with a different drivetrain.

There are other more modern systems with a crank mounted freewheel for enduro and DH bikes, allowing the rider to change gear while coasting in anticipation of a pedaling section. Similar to gearboxes, the idea comes back once in a while but never really takes off massively.

There was a french company named HXR components which used to produce that, I think they went bankrupt. Nowadays there is the Rocksteady Magic from boutique euro brand Intend: https://www.intend-bc.com/products/rocksteady-magic/


Fitting all that (battery, motor, controller, voltage converter, charger) into a small package is pretty impressive.

Mid-drives are certainly superior to hub-drives, so that's another plus.

Can it pedal assist? i.e. only kick on when pedaling. That's often a legal requirement.

Doesn't mention cost, weight, or battery capacity.

I'm assuming most of the parts beyond the aluminum chassis are off the shelf. It would be a nice thing to open source, or at least sell the plans so anybody* can build.

* with access to a machine shop


In the video it appears to be only throttle controlled. I have no idea what kind of e-bike regulations India has, but I wouldn't be surprised if the answer is "effectively none". Hopefully they won't make the same mistake many other countries did with the pointlessly complicated class system for e-bikes.

> Can it pedal assist? i.e. only kick on when pedaling.

Looks like it drives the chain, so unless you have a freewheeling front hub pedaling may not be optional.


I was confused about that. It looks like it drives the chain, but then in the video after installing it or while riding it he's not pedaling.

But then when watching closely, I can see there's a cut in the video between the device being placed on the frame and him testing it and in the cut the entire bottom bracket has been replaced and the chain is now making a different path through the machine, so I assume the bottom bracket needs to also have a freewheel to make it work, plus you'll need a new chain (or to join a couple of chains) to make it fit.


The video is a bit strange: https://youtu.be/SFsnS0Yb1Bs?feature=shared&t=96 It appears to show the front sprocket spinning, but the pedals stationary.

I assume this is a "freewheel crank" https://en.wikipedia.org/wiki/Front_freewheel


It does say a 40km range, but ebike range estimates are often highly optimistic.

I converted my bike, do 36km per day and still have 40% left after that.

> Mid-drives are certainly superior to hub-drives, so that's another plus.

can you explain the difference for someone who never heard of either?


Mid-drives apply power at the pedal and therefore go through gears, and therefore can go up steeper hills for the power.

Hub drives apply power at the wheel hubs. They are cheaper and smoother (no backlash), so depending on application hub motors may be superior.

Personally I like help up all the hills so mid-drive all the way.


Agree, they each have benefits. I broke a chain with my mid drive in winter and really wished I had the redundancy of a hub motor. Also, many many bikes cannot easily fit a mid drive retrofit though I think the diy community isn't as large these days given the variety of ebikes available

Their website says it's about $162

Remember to get a strong frame, as a hub motor can shear a weak frame surprisingly easily. The front fork snapping off in a turn is no fun.

Edit: I said hub motor by accident, but it applies to these motors too.


This is an interesting alternative to existing kits where you need to replace a wheel (hub-drive) or do surgery on your bottom bracket (typical mid-drive). It also appears to not need an external charger (the charge port appears to be a universal C14, the same as a computer) which is very convenient.

On the downsides, I have severe doubts over the battery cell quality at that price point, and it looks significantly heavier than other options from the metal case alone (I don't see actual specs for weight).

Love the demo video. The mud and fire scenes made me cringe, which I'm sure is exactly what they were going for (as the motor keeps spinning regardless of the foul treatment)!

I will keep my standard mid-drive conversion kit (I've used TSDZ2 and DM-02 in the past) but always love to see alternatives coming online for other segments of the market.


It reminded me of the Sinclair Zeta[0][1]. I hope their product work out better.

[0]: http://rk.nvg.ntnu.no/sinclair/vehicles/zeta.htm

[1]: https://www.grantsinclair.com/vehiclehistory


Clive Sinclair is mostly remembered for his computers but he was incredibly ahead of his time in the electric vehicle and personal transport industry.

Too ahead of his time, unfortunately, because the battery technology to support his vision just didn't exist, and consumer sentiment wasn't really there yet.

I'm sad he didn't get to see his visions come true.



I think readers of hacker news That find the original post interesting might enjoy this as well:

https://bimotal.com/

It's a different product for a different market, but a really cool idea and the people who have been working on it are super smart.


Anyone particularly excited about this concept might be interested to know that it already exists (for a little less than $400).

PikaBoost[1]

It works. But not nearly as well as an ebike, of course. Here's a youtuber doing a fairly in depth review and test of one [2].

[1]https://livall.com/products/livall-pikaboost-2-electrify-you... [2]https://youtu.be/m_wVzoNrDL8?si=gCwvHZgrsV3klZ49


There is also that extra small friction system from velogical which has the advantage of allowing you to use a mudguard: https://www.velogical-engineering.com/velospeeder/product-in...

I'd have to forego my saddle bags and maybe my mudguard for that one.

The chain is spazzing out in every shot like it's tightening and loosening over and over again. Mid drives already wear out chains quickly. Seems like this is just asking to snap a chain

IANAEE but is the frame itself enough to dissipate heat of the internals while being sealed shut like this?

love the concept and would like them to succeed. just feels like that the relative ease of installation also means it might be easier to steal, especially with the battery integrated inside the kit.


I got a Zehus Halos [0] for my racing bike, a Commencal Stewart; I ripped out all of the gears and replaced the rear wheel with a wheel from Nfixed [1] who builds wheels with the Halos. Conversion couldn't have been easier -- just replace the rear wheel, take away the gears and replace the front blade. The result is an amazing bike, fun, easy, beautiful.

I still haven't pushed the range to the max, but with break regeneration and moderate assistance, it seems like the range would be 50-60 km, which is more than enough for me.

I highly recommend it!

[0] https://www.zehus.it/product-categories/all-in-one

[1] https://nfixed.com/products/gen3-0-zehus-halos-all-in-one-sm...


How are the pedals not moving with the chain?

Not even this would be incredibly dangerous (pants caught on the chain? the motor won’t be stopping at all), but it would make it an illegal e-bike in much of the world since it doesn’t qualify as pedal assist, it’s now a flimsy motorcycle.


I would think the pedals would stay in the same position because of the back ratcheting. Think of when you're going down a hill and you hold your pedals still while accelerating down. I'm no bike expert though, I may be wrong haha.

For most bikes this ratcheting mechanism is in the back wheel, so when going down a hill the pedals, the chain ring, and the chain are all staying in the same position. In the demo the chain ring and chain are moving under the motors power, but the pedals are remaining still.

Thanks for the clarification! The more you kbow I guess haha.

This is impressive engineering. So much better than the available ebike conversion kits. I want one!

That looks a lot less robust than a lot of the ones on the market but also a lot easier to install. Might be a solid approach because the install is off-putting to very many people.

Here is a HNer that made his own e-bike : https://news.ycombinator.com/item?id=29198205

That could be a really quick retrofit -- looks like only the chain and chainguard would need to change for the standard utility type bike.

Top speed would probably depend on the rear cog, unless they're doing something really sneaky.


I did this to my road bike using a comercial kit: https://boostbike.uk/

It completely changed my commute.


Let's check the numbers. They claim :

  Range: 40km
  20 min pedaling charges 50%
  Top speed 25kph
If a 70kg well trained amateur cyclist can output ~200W for an hour [1], so let's guestimate 130 for an average person. That would mean the battery has a capacity of at least: 130W * 2*20min = 86.6Wh. The efficiency of the motor/ESC is not considered.

So at 15kph, it would take 2.6 hours to reach the stated 40km range. 86.6Wh / 2.6hrs = 32.5W

A model based calculator [2] says that with 32.5W you indeed cycle at 15.5kph.

LiFePo batteries have an energy density of 325Wh/L, so we would need a battery volume of: 86.6Wh/325Wh/L = 0.27L, but a quick search for an example online reveals that a commercial 10Ah 12.8V takes up 1L. That would seem to fit within the product.

I was initially doubting the claims, but it seems to check out ?

[1] https://blog.2peak.com/en/what-are-the-average-watts-of-a-go... [2] https://www.gribble.org/cycling/power_v_speed.html


Unusual for ebikes to use lifepo as they are much larger and heavier than standard lithium ion. Especially in cylindrical formats that are needed to make bike friendly battery shapes.

Fair point, then even better for fitting the battery in the case.

Also curious what "50%" means in their specs; the top power for the motor is 250W and top speed of 25kph would take ~100W on flat ground, which would throw off your calculations considerably. (Not that I take issue with your calculations, they just haven't published enough data to know what you'd actually be getting.)

More than happy to learn something through a mistake in my calculations !

Regarding the 50%, I assumed that they stated this number because this is when the battery is in bulk charge and can suck up as much as you can give it.

For the 250W, I hadn't even seen that, good catch. Maybe 250W is the peak power that cannot be sustained for thermal or current rating reasons ? 250W for a 12.8V 10Ah battery is 2C, so that should not be the limiting factor. I do not know about the motor or the ESC

Also, for sure the maximum range is not achieved with the top speed !


Agreed on all points! Very plausible that 250W is peak; other motors on the market vary whether they state peak or sustained so the waters are a little muddy (e.g. I know that the popular BBS02 "750W" motor can put out over 1kW peak).

> with 32.5W you indeed cycle at 15.5kph.

With a perfect bike in a velodrome, maybe.

But on Indias rough roads with an old mountain bike, I suspect this number to be double.


I’m missing something, what’s unrealistic about 15.5kmh? That’s absolutely crawling on a bike.

What he meant was to go 15.5km/h with a good bike on a velodrome might require 32.5W, but it would require quite a bit more power on rough dirt roads with a shittier bike

It is a good point, but I highly doubt the stated 40km range was measured with a rusty bike off road. I think it is fair of a seller to state their range in good conditions.

In another video it says expected price 15000 - 20000 rupees which I guess is like £150 or $200. Quite cheap as these things go. (vid, not in English https://youtu.be/HoTucoz1Uro?t=111)

Cool hack if I've ever seen one in this place! I love how "steampunk" it looks (for lack of a better term). Though I feel like if they're gunning for global appeal they would have to streamline the looks a lot.

This is so awesome I might have to watch "3 Idiots" again.


Really cool product. Great Demo video. This guy is doing it right

Very cool concept. It’d be helpful if there was videos of it working or some details on the process you made to build it. Or even why you did.

> It’d be helpful if there was videos of it working

It was easy to miss, but the first image on the page is actually a fairly detailed video showing it working. Here's a direct link to the video.

https://www.youtube.com/watch?v=SFsnS0Yb1Bs


This is a simple yet slick video! It clearly highlights the benefits of this invention. It was interesting to see the use of the uncommon word "inlet" (2m05s), which is the correct word for a socket on a power sink that accepts a power cable.

On the other hand, I didn't like the non-standard use of metric units: At 0m34s, "25 KPH" should be "25 km/h" (k is not allowed as an abbreviation of km, and p cannot stand for per). At 0m38s, "170KG" should be "170 kg" (metric is case-sensitive). At 0m43s, "40 KMS" should be "40 km" because plural symbols are not allowed (and can be confused for the second, e.g. N⋅s is newton-second and not "newtons").

At 2m20s, the claim "20mins pedalling charges 50% battery" sounds too good to be true. For example, 20 minutes of vigorous pedaling on a manual bike will not let you travel a distance of 20 km (half of the claimed battery range).

At 2m29s, "8 crore bicycles & rickshaws running across India", meaning 80 million, seems like a very small number for a population of 1.4 billion.


>At 2m29s, "8 crore bicycles & rickshaws running across India", meaning 80 million //

That's a new word for me (en-gb native). I assumed it meant something like '8 brands of...'. Thanks for clarifying.


Yeah, I had to research "crore" today due to the word being mentioned. Another Indian number word is lakh = 100,000, which I only knew since a few years ago (living in Canada for 30 years).

https://en.wikipedia.org/wiki/Crore , https://en.wikipedia.org/wiki/Lakh


The home page is a video of it working. Including throwing gasoline on it when it's already on fire. While it's running.

The practical demonstration in the video are fun and memorable. Realistically I'd take a lighter case without ability to submerge the whole thing in mud and set fire to it, but I'm in urban UK. It seems to be built for a warzone, milled out of solid aluminium?

Or built for a place with only dirt roads, heavy muds during a rainy season, probably very limited ability to get spare parts, and a desire to use it for years after buying it.

Which was cool until he littered the bottle of gas into the irrigation ditch behind him

totally missed it at first but just watched it. badass. Inventions that build upon what is already in the market are the most ingenious

okay, the 20 mins of pedaling charging the battery to 50% is a nice feature. there's plenty of time I'm pedaling my bike without pedal assist that could be recovering some of the battery on all of my trips.

Every bits of the demo video is awesome. I want to make friends with you.

That's neat retro styling, maybe part Flash Gordon?

Love it. I want my product to have a video like that.

8 crore = 80 million.

Misleading title - this won't work on a recumbent.

Video makes it look like you can just drop it in and go. No. You have to change out the chain for a longer one.

Bike chain is fairly standard - the kit could ship with a chain tool and an extra few inches of chain.

I have four bikes, they all need a different kind of chain.

The only _fairly standard_ part in a bike is the saddle.


That's really easy, you can also just add some links since bicycle chains are pretty standard.

Why? Does the chain wrap around anything, or is it just driven from a sprocket on one side?

I assume minor deflection could be handled by the tensioner inherent in geared bikes.


this wont work on several lady bikes because how their frame is designed

Tongsheng tsdz2 750W mid drive torque sensor motor conversion kit is $310 on aliexpress.

For readers, see also Zehus hub motor, I've seen it used in higher end e-bike conversions.

Why would i? "Analogue" (pure mechanical) tech is king.

If your livelihood depends on 50+ miles travel every day, and you're 55 years old, you may well appreciate the assistance.

Given the specs, this product is absolutely not an help for this kind of constraints.

My take in the ebike/bike debate is just this: if you're not sitted in yet another car, you're winning.


I prefer "accoustic" (as in guitars)

I'm mystified at the multitude of "this is great" comments on an essentially unspec'd and implausible product. Is this elaborate joke that everyone's in on?

HN has been an engineering-oriented forum and bicycles are "real engineering". Every kind of modern bike is engineered for it's intended use and the idea you can add power and weight without consequences should be suspicious to the engineering mind.

Note: The video shows a USB cable for a charger, which couldn't charge a large-ish battery in an acceptable period, at one point it seems to show power imparted direct to the tire (which would lose a lot of power) but really, how this thing works at all is hard to tell, it's kind of silly to take seriously, even but jeesh.


If you were as attentive as you might think you are, you would have noticed that the USB plug being inserted was the host side, so it's the side generally which charges the connected device.

USB-C does 240W, what makes you think it can't charge an E-Bike battery? Most are under 500Wh and would take at most 2 hours.

Also it looks to be a USB source, for charging your devices, not the other way around.

It's a nice bit of engineering, making it an all in one package that can bolt onto a frame with minimal effort is quite neat.

I'd love to know why you think it's implausible, from all my work on ebikes it looks legitimate.


Do you believe it's fake? There are many kits on the market to turn old bicycles into e-bikes.

As to the USB charging - that's an outlet for charging things like mobile devices, not for charging the battery on the bike.


The right side is what seems like a C13? C14? plug.

It has also a USB outlet to charge your phone.


Sure there are tradeoffs to not having a nicely integrated system, but there's nothing wrong with having other options for people to pick from.



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