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Comment by milesvp | Hacker News Reader

A word of warning. I started looking a little into motor assist bike mods a few years ago, and very quickly you find that the biggest mistake people make in this area is not altering any of the other systems of the bike. That is, they'll put in the motor, and then just ride. Which works, but then you find that your brakes aren't quite good enough to stop quickly at the new higher speeds. Shocks are no longer good enough to prevent certain issues as well. Maybe the frame needs reinforcing... I don't quite remember the whole laundry list.

I don't know how important some of these improvements are, I just remember reading this advice more than once, and safety is important. So be smart and do your research.

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I made an ebike from a brand new Decathlon "rockrider" MTB 3 years ago, and have ridden about 10k km on it since. I changed brake pads often, and tires a couple of times, etc. but the frame is fine.

It's really life changing. I used to ride a motorcycle, and I still own one, but I seldom use it anymore; the ebike is absolutely perfect for short commutes (under 20 km each way).

That said, complete ebikes are more available now, and at good prices, so conversion kits are becoming less relevant.

Don't complete ebikes cost as much as used cars?

I bought a decent e-bike for $1800. It’s got good components (shimano) and disc brakes. I’ve put about 2000 miles on it so far and use the pedal assist 30% of the time, turn it off to get more of a workout when riding home.

You can get cheaper and way more expensive but I think this is the sweet spot. (For comparison My non ebike is a hybrid commuter which was about 600)

Not if you factor in insurance (especially for young males) and budget ebikes start at $1000 and even at entry level they are still very capable. Plus car repairs and gas.

Besides people always get suckered into getting way nicer/newer cars than they really need (myself included). Financing is a difficult thing to keep at the low end. So in practice it’s not really comparable. But cars obviously have plenty of other benefits.

High-end complete ebikes cost as much as a car.

So do high-end non-e bikes.

There is a hugh market for a reasonably powerful ebike.

The ones I like are $2000 to $12,000.

I'm waiting for a Henry Ford type of guy to bring those costs down. I guess the lithium batteries are a big factor in costs?

In the mean time, I'm sticking with my old Zapp bikes. I need a battery though.

When someone does come along and create an e-bike that's fast and comfortable enough to coexist with cars on every road short of a limited access highway it will instantly be regulated into oblivion with a bunch of hand wringing about road safety. See mopeds for an example. As soon as they got both good and cheap they got regulated to the point where a crappy car has a better value proposition.

You can already see a litany of comments expressing support for regulating ebikes so they remain a novelty niche in this very thread.

In trafic a moped is better than a car, and an ebike better than a moped, regardless of regulations. If they impose a full helmet for ebikes I will hate it, but still choose that over a car.

In my locale, mopeds / scooters had a very narrow niche, among college students and some employees, because they could be parked for free. You didn't want to be driving through the campus in between classes because of the scooter traffic. When the university started restricting and charging for scooter parking, the scooters vanished. At the same time I've seen practically no e-bikes in the racks on campus. Most student housing has no indoor bike storage, and they're hard to carry up stairs so it's a problem to find a way to charge them. On the other hand, as I've told my kids, "you were born with feet, you can pedal a bike." Conventional bikes have returned to their proper place at the top of the student transportation food chain.

I'm really baffled at (e-)bike prices remaining so high. There's certainly not more research than what goes into cars, admittedly amortized over smaller production runs, and battery packs should (should, but don't) cost very little (at 100$/KWh, my bike's pack should be a whopping 43 bucks, let's say 100 if we include the frame mount, the lock, the wiring and the charger).

There is SO LITTLE material overall in a bike, with 99% of the tech having changed little since the '70s, so I guess it's not patents or IP either. It's not the wheels, I can buy replacements for little. It's not the shifting system, a crappy one is 100 EUR and a decent (low-end) Shimano is under 200. It's not the chain, those are 10 bucks, maybe 25 for the higher strength ones appropriate for an e-bike. It's not the motor, as I can get a conversion kit off ebay for 150-200, which includes a wheel and electronics.

Yet, 25kg of ebike costs 12% of 1000kg of a low end city car, while using 40 times less material and not having to undergo all the same rigorous testing, homologation and what else.

What am I missing? Is it all in the frame? Is it all profit? Am I looking at this from a completely wrong perspective ?

Regular non-electric bike pricing gives some good clues. There are decent bikes made by Asian ODMs quite affordably, with simpler but good enough parts like steel frames and 3 or 7 speed IGH. They're not that easy to find on the market because it's hard to tell them apart from the crap ones, and this state of affairs is profitable to people selling bikes.

Also there's been a lot of consolidation, and there aren't many big bike manufacturing companies, so some illegal collusion is not out of the question.

Another factor is used bikes. It's hard for a company to compete with that on price.

I completely agree with you on prices for bikes being to high. I think the reason for it is that bicycles are considered luxury items. They cost so much because people are willing to pay more and there isn't enough volume in bike sales to justify large economies of scale that drive down the price - used bikes eat up that part of the market.

If you look at bicycle parts then it seems like half the parts get updated once or twice a decade. Yet the old stuff was mostly fine.

Retail batteries are not $100/KWh. If you source high capacity cells from China, you can get maybe $140/KWh. That doesn't include a BMS, enclosure, labor, etc.

Depends on what kind of used car you're thinking of. (I'm being anal; it's a weird analogy given you can probably get a used car for <$100)

Anyway, the cost of ebikes has gone down a lot over the years, especially as more and more competition shows up and production of various parts (batteries, motors, control units) has scaled up. I just had a quick boggle, ebikes start at around €1200 at the moment (cheaper too, but those are folding bikes).

You can buy a shitty car for the price of a decent e-bike.

The e-bike has maintenance costs close to 0.

Cars need insurance and fuel at the very minimum.

> The e-bike has maintenance costs close to 0.

Not perfectly true. You have to renew brake pads, tires, chain and cassette at regular intervals if you ride a lot. They cost way way less than car maintenance though.

In France they start at about €800, or €500 when they're on offer.

Depending where you live, how much paperwork you can cope with and how much you earn, the government will give you up to 50% of the purchase price back.

Most of the cost of a used car comes after you purchase it, though : )

> Most of the cost of a used car comes after you purchase it, though : )

Very true! French cars are certainly no exception to that rule :-)

> how much paperwork you can cope with

This. I gave up after reading the list of documents I would have to produce.

Vive la paperasse ;)

It varies by metropole. Here in Nice it seems straightforward.

Possibly. Sky's the limit, as usual...and there are some dirt-cheap _very_ used cars available, so that's not a very useful comparison.

I'm reminded that my college roommate traded his unworking truck for a case of good beer.

He got the better part of that deal. (You have to put a price down on the title when you sell. In this case it was technically $1...)

An Ancheer ebike from Amazon cost around $1k, and while possible, it would be hard to get a car for that price. It seems pretty well made for the price, but it doesn't include the best quality shifters. I can set the saddle high enough for my 6'5" self, but I do want the handle bars raised as well. I suspect that for people 6' and under, it would be fine as is.

I think ebike is a misnomer. These things are really e-(motor)cycles. This confusion is making it really hard for me to search for what I need. All I want is an assist to take the edge off of hills. Don't need to cruise at 30mph for an hour.

Search for a 750 watt motor. That is the upper limit in many countries for a standard commercial ebike. Bafang and Tongsheng both produce popular motors.

Google says those cruise at ~30mph.

You can get really nerdy and calculate this the way triathletes/time trialists do with a tool like this[0]. I plugged in what I think my numbers are for mass and my relaxed ride CdA and on my road bike and you're on the money.

[0] http://www.aeroweenie.com/calc.html

That's really helpful. It predicts 534 Watts to get me (110kg, 0.4 CdA) to the 45kph limit for Class 3 California bikes.

The Grin Technologies motor simulator https://ebikes.ca/tools/simulator.html predicts (the "Load Line") 837 Watts for "MTB upright", 648W for "MTB, Tuck" and 570W for "Road, Tuck".

I do find that in an upright position it takes 100-200W of human power in addition to 750W power measured at the input to the motor controller. The controller's pretty efficient, but the motor (GMAC) is only 85% max, so there's maybe 570W at the axle. The US CPSC and California laws aren't clear whether the 750W/1 horsepower limit is power in or power out, but power in is what shows on the display, so I limit it to that. Also, even a mild grade will cause the motor to approach the 70 deg C limit I chose after 1 minute. I live in the flattish Santa Clara County, but I'd definitely want a mid-drive if I lived in a hilly area. A 250 or 350W Riese & Müller Delite https://www.r-m.de/en-us/bikes/delite/ I test rode needed a lot of human power to hit the 45 kph max, but it climbed hills in Larkspur like a goat.

750W will have no problem getting a recumbent bike to 30MPH, but don't count on it for an upright.

Oh, and to see what 700W from a human looks like, an Olympic track cyclist toasts a piece of bread: https://www.youtube.com/watch?v=S4O5voOCqAQ

Yep. Bradley Wiggins's 2015 velodrome hour world record was 440W (since eclipsed in distance but not power). This puts into perspective how cheap power is in the industrial age. His hour record was the equivalent power of 35 grams of gasoline. Or it's about 5 not great power tool batteries (eyeballing eBay listings). It's gonna be tough when we have a world built for nearly free energy and we don't have the free energy anymore.

I had guy in lycra overtake me at that speed (slight downhill). He smiled and took off.

It's plausible. Pro riders put out 400-500W to do ~30 mph, but are likely in a more aerodynamic position than most ebike riders (or drafting).

Pro riders can do 30mph at around 270-300W on a flat surface as they’re typically very skinny. I need about 350-450W to do 30mph as an 88kg/1.88M male.

Hm. You’re right. Bad suggestion. Overkill.

I think the phrase e-bike generally refers to a bicycle, with operable pedals, that also has an electric motor to assist when peddling, and possibly a throttle.

When I think electric motorcycle, I think of something that does not have pedals at all.

One issue is that the pedals could be practically cosmetic, if the power added by the motor is such that pedaling is unnecessary. This was true with some early mopeds too -- the pedals were pretty much good for starting the motor and nothing else. I'm seeing more of this as e-bikes evolve towards smaller diameter, wider tires and heavier frames.

The US "class" system seems useful, inasmuch as it more or less specifies the capability of the bike with and without pedaling. I'm all for adding a new transportation / recreation option, and have adopted a wait-and-see attitude for how the technology and its use will evolve. So far, e-bikes have not affected my use of a conventional bike, except for people asking me when I'm going to get an e-bike.

Huh, I've never seen a moped that you could pedal like a bike even in a photo. Apparently the "ped" is from "pedal," not "pedestrian." I wonder if eBikes will follow the same path? I don't think they will, a gas motor is already disruptive enough that you may as well become a motorcycle.

I've never seen a moped that you could pedal like a bike even in a photo.

As an example, https://en.wikipedia.org/wiki/Puch_Maxi

I wonder if electric starters killed the pedals. I grew up in an area that was pretty heavily car-centric, so we didn't see a lot of alternatives. The Schwinn store got the Solex Horse, which had pedals, but they were really only useful for starting as there was one gear with a low ratio.

The only next thing we saw was the Honda Spree, which as I recall had an electric starter and whatever qualified as an "automatic transmission," and I think that class of scooter is still more or less the standard today. It seemed like a big step forward in terms of ease of use.

In Sweden there are different classes depending on if the motor can drive when you are not pedaling.

EPAC or Pedelec is a term used for bikes that meet the EU regulations, assist should cut off beyond 25kph (15.5mph) and you only get power when you cycle. I think there's a motor wattage maximum too so that might help your search.

Those seem to be the magic words to find what I'm looking for, thanks!

yup, and 250W continuous

And the great bit is that if you are ignorant of these laws and get caught on an electric bike doing higher speeds then you get a penalty as if you are riding a motorbike without insurance or a license - aka penalty points on your regular driving license, plus all the other court shenanigans.

I'm all in for sensible regulation, but don't structure in a way that it's impossible to buy mid-speed ebike because no one knows how to certify or suddenly it costs 4x more for no apparent reason.

We call it a class 1 ebike and they are easy to buy in USA.

This could be a market problem, like trying to buy a small car these days. People are demanding bigger, faster, more range. I know several people with e-bikes, and most of them are on their second or third bike in pursuit of more speed and power, fatter tires, shocks, etc.

A used bike might fit your bill. Or the DIY route. The friction motor might be a bit iffy, but you might be able to buy an electric front or rear wheel for not too much and use the same electronics.

Friction motors are not great in the rain. The tire tread type and width, the pressure on the tire and the material of the friction drive surface are all difficult to get right. These kinds of motors are very noisy too.

This distinction is becoming a big problem in our local mountain biking community.

Most of us really wouldn’t mind if people who needed a little extra help (older people, injured people, people new to the sport) were riding bikes that provided a small assist to help out with the hills. It’s actually great to see older people being able to ride again with some help from a motor, for example.

But instead, we’re seeing a lot of e-bike builders abusing the concept to hack or build bikes that are basically electric motorcycles. It gets old fast when your local mountain bike trail is now crowded with kids motoring up the mountain on their modified e-bikes without even pretending to pedal. It’s even worse when they end up deep into trails they’re not qualified to ride with a dead battery and no natural ability to pedal back out.

The end result has been a blanket ban on e-bikes on most trails and a lot of animosity toward e-bikes. I wish there was a better compromise, but after watching all of the dumb outcomes play out on my local trails from a small handful of people abusing the concept, I understand why it had come to this.

Do bans work? I could probably build a bike that you really couldn't tell unless you took it apart.

Partially. My local trail bans e-bikes and off-leash dogs, but I still run into both on a regular basis.

Occasionally there will be someone waiting at the trailhead writing tickets to people who come off the trail with an e-bike or an off-leash dog. This seems to work as word spreads through Facebook groups and people stay away. Also generates some decent revenue when someone can write tickets for an hour and hand out a couple thousand dollars in fines for blatant violations (they stand right next to the very clear signage at the trailhead)

If it's indistinguishable from a regular bike, it's probably not one of the 1500kW bikes their organization had a problem with.

1500kW bike, that's a beast.. with wings and a pocket fusion engine, I presume .. xD

It powers the neighborhood.

58 year old MTB’er here. I was looking forward to getting an eMTB in a few years to keep riding. Feels like the window is closing as many place around me ban eBikes for the same reasons you describe. It’s going to be pretty disappointing if I can only ride at the “eBike Park” full of kids on Sur Rons (basically an electric dirt bike). Oh well, I can still ride for now.

if you get your doctor to right you a note, it can be an assistive device which is not covered by a ban. i am not a lawyer, this is not legal advice, but i am middle-aged.

I think if this is true it highly depends on who owns and mamages the land.

I am pretty sure this is not currently true on almost all US National Forest land. Anything with a motor qualifies as for motor vehicle there and you will only be allowed on trails marked for motorized use on the MVUM maps. This includes mobility devices

The shocks on most cheap bikes are questionable at best. Lots of stiction and you're lucky if there's any dampening at all.

Downhill mountainbikes are popular conversions. They are designed with high speeds and impacts in mind. The cost may be prohibitive to many DIYers though.

For high speed (50km/h), adequate tires are also necessary. E50 rated tires are now widely available that can handle the speeds and loads.

DIY downhill ebike is around $4000 NZD, while the cheapest, lowest spec downhill ebike from manufacturer is $6000 or so. There's a sizeable savings to be made.

Yeah I think you don't need to do this to an expensive bike. Mechanical disc brakes and just a front shock are probably fine if you want to go 50km/hr. A heavier sturdier frame and burlier tires are ok because it is powered.

I wouldn't recommend converting a road bike as they are more fragile.

I’d love a utility ebike but afaik they just don’t have enough weight and hence - the grip at high speeds to be safe.

I’d guess e-scooter/moped is next best thing tho parking is an issue in some places.

They are fine at 45-50 km/hr. That keeps pace with car speed on residential roads fairly well. Any faster and I agree you could look at scooter or moped.

Mechanical grip is entirely a function of tire compounds. In fact, ebikes can have even more tractive grip because you can make them AWD! This makes them much safer in snow and ice compared to other two wheeled vehicles.

What is this "shock" thing you speak of? Is this a nasty side effect of "e" bikes?

A "cheap" bike is just a rigid frame with rigid forks.

Imperfections in the road at 30mph are very different than at 15mph. Especially on a cheap frame.

A fat tire can stand in for a shock, but "cheap" bikes don't usually fit 3" of rubber either.

Relatively cheap electric fatbikes like [1] are currently very popular in Italy, as far as I have seen on a recent holiday:

[1] https://elettrica-bike.it/en/product/fat-bike-vulcano-s-tipe...

Shock absorbers = Suspension

I don’t see any ebikes being sold without at least a 50mm front shock. The added weight of the battery+motor makes it essential

I have a Trek Allant+ 9.9S that is shockless.

Wow carbon fibre, and the tyres don't seem too thick.. How does it ride?

Ahhhh I think I understand - it's a "speedbike" right? So only for driving on roads like a car, so there's no question of forest tracks or gravel walkways.

I upgraded from a Trek xm700+ with a front shock. Both served me well but I don't miss the shock.

Yep, they're both commuter/cruiser type bikes, so probably not best offroad.

Both have the top end Bosch Class 3 motor, so they're usually against the rules on trails in my area.

Being pedantic, the suspension of the xm700+ doesn't have a shock. Its a simple coil spring that gives the wheel some room to wiggle. Shock absorbers actually dissipate that energy with oil/air/rubber.

If you ride it like a bicycle and try to avoid potholes and curbs, simpler designs work great.

In the US midwest at least, almost everyone who buys a cheapo bike from Walmart, Target, etc buys what is basically a terrible hardtail mountain bike. Front fork suspension, wide knobby tires, etc.

My assumption is that people buy them since they are a touch more comfortable than a full rigid bike frame.

"Downhill" mountain bikes is a term of art and, as an avid mountain biker, I'd guess not actually the type being used for conversions to commuter bikes.

You're much more likely to target a "trail" full suspension mountain bike or fixed tail bike. You'll have a lot more cost options and they're more suitable for a commuting purpose, they'd still have plenty of travel and braking compared to a standard commuter or utility E-bike. As a note, my mid-level trail bike came with a better set of brakes then my high end cargo hauler e-bike which weighed about 10 times as much.

Yeah there’s no way you could use a DH bike as a daily rider, even with an electric conversion. The geometry and shock travel is just wrong (when you try to pedal a DH bike on the flat, you look like you’re riding a chopper with the added bonus of your knees going up to your waist)

The implication is that most DIY ebikers don't bother with pedalling. Hand throttle keeps you at 50km/h fine.

Long seatposts that bring you up to a typical height are fine. The suspension is doing the work, no need to leave the saddle.

Another big issue is stealability - as a cycle commuter I considered an electric conversion right up until I remembered my office is in one of Oxford's black spots for bike thefts (the whole area is bad to be honest, but I'm in one of the worst places for it). The key to preventing your bike from being stolen by some fifth generation product of inbreeding isn't to have the best lock, it's to make it less worthwhile to steal than the bikes around it. The crappier your bike looks the less likely it's going to be stolen, an obvious electric bike parked with any regularity is going to vanish pretty quickly to a thief with a bolt cutter no matter how good your lock is.

So true. I spray painted my bike a flat black and put crappy looking fenders on it for wet riding. It looked like hell on the bike rack.

Put a lojack into the frame and have fun catching them.

Yeah so fun to have to figure out a way home, how to get to work the next day, having to deal with the police, retrieving the bike, hours spent on fun

The police don't want to help retrieve your bike, even if you know exactly where it is.

Or AirTags.

#1 rule people forget is: how fast can you stop. You see it with young car guys vs old ones. Old dudes upgrade the brakes before the turbo and visa versa

Some of that may be because brakes on old cars (drum brakes, undersized discs, etc) were often terrible. I think stock brakes have been quite good on most cars in the last 15 years or so.

For example, a 2021 Chevy Surburban is a HUGE SUV, but does 70mph-0 in 166 feet. Better than a 1999 Camaro Z28 or Mustang GT, at 184 and 182 feet, respectively.

Are those numbers with threshold braking or engaging the ABS?

Not sure, but here's the sources:

The article with the Suburban data: https://www.caranddriver.com/features/a35048882/tahoe-yukon-...

Mustang and Camaro:

https://www.caranddriver.com/reviews/comparison-test/a151408...

I wonder how the 20 year old GT cars would do on modern tire construction and compounds?

Probably pretty good but not better than modern cars.

In the 2000s one of the car magazines tested top trim (big engine, race package, etc) classic muscle cars on modern tires and they put down respectable numbers, not better than 00s cars, but respectable.

Suspension and chassis stuff hasn't come all that far since the 90s so high end cars of that era should be able to handle very respectably compared to modern stuff. The differences are more apparent at the low end. Modern crossovers handle very respectably for what they are.

Obviously modern stuff will always win in a straight line because power levels increased massively over the past 20yr.

It's a trope from the days when you could still get vehicles with manual brakes with no power assist. As you can imagine enabling such a vehicle to go faster greatly increases the workout the operator is going to be getting to the point where if you want to drive aggressively in stop and go traffic the operator is the limiting factor.

Your statement reminds me of my concerns over electric scooters. They don't go superfast - maybe 30kmhr(18mph) - but the centre of mass(hips) location compared to the front wheel looks like a bad braking scenario...

You learn to shift your weight appropriately, but yes - definitely something to be aware of as it throws you if you're not expecting it. I'm speaking from experience on an electric longboard, but ridden both. I find the scooters you're more instinctively likely to brace on the handlebars.

#1 rule people forget is how fast you can stop isn't determined by the brakes as long as they're already strong enough to lock the wheels or cause loss of control, which they always are on cars and often on bikes.

The bigger concern on cars is, how many times can you apply the brakes before experiencing fade or overheating. But yeah - there's a reason old guys use expensive tires too!

I really, really, really, really hate this trope.

You have to go back to the days of drum brakes and no power assist for this to even be close to true. Yet it gets tossed around in every comment thread about modifying anything that rolls because it gets easy virtue points from the safety crowd.

OE brakes on damn near every vehicle made in the last 50yr from a Walmart bike up to a semi truck are more than capable of stopping harder than even nice tires can grip the road. Will you go through more consumables if you use the vehicle harder (enabled by having more power on tap) sure? You'll also go through more tires too. That doesn't mean the brakes are insufficient.

I did a couple of conversions but mostly just replaced the rear wheel with a built in motor. It is a dirt cheap mod and it is very modest optics wise. Unlike other options. In general it is very advisable to look for spots on the frame where the power of the motor will be attacking. Most parts are designed to handle stress just from one direction only. That is why I am not a fan of conversions that utilize front wheel motors and/or big guns like 500W+ motors - even for the rear wheel.

If you limit yourself to like 25mph thats a nonissue though, all bikes are built to handle that speed.

You'll add approx 20-30 pounds with the battery and a hub motor to the frame and that can make stopping more difficult, it's not the same as a heavier rider.

Not sure what you mean. The range of weights on any given adult bike beyond, say, extra small, are much wider than 20-30 lbs. It's exactly the same as a heavier rider as far as stopping distance.

The handling of the bike with weight added on the frame (especially if it is high) is quite different under a hard stop than just adding a heavier rider with the same weight.

You can shift towards the back of the bike with your body for instance.

> especially if it is high

Like the body of a larger person or a person wearing a backpack?

I mean where you mount the battery pack on the bike. On a rear rack above the tire is probably the easiest but its not great for stopping or handling, especially if its more than ten pounds.

On the down tube is better. Carrying the batteries in a back pack can be done. I did that for a few months.

Since the battery and the motor are usually low on the bike, it's actually a little better than a heavier rider.

European city bikes are most definitely not built to go 25 mph. A Dutch step through bike with a backpedal brake at 25mph would be very sketchy.

This is a good point. I bought a used bike for about $100 online and have now done about 5K KM using a cheap conversion kit online, with minimal maintenance. However, I was lucky and also bought a low power kit (250W, while 1000W kits are available). It is a great way to get around but some caution is required. In the wost cases, front wheel drive motors can bend/break the front fork on a ride - not a good situation.

I think the biggest mistake people make with eBike conversions is putting in too powerful of a motor. If your motor lets you bike faster than the brakes or other components can handle, then it's too much motor.

Get an electric moped/scooter/motorcycle if you want to ride faster than you can pedal.

Yes, also include the added weight though. The converted bike will take longer to stop at the same speed just because you added a motor and battery.

Safety is definitely important but I have a hard time lining up this advice with how I ride my current bike. I ride downhill at up to 40 mph and my brakes, frame and shock work fine. On my mountain bike, I jump off 6 foot drops regularly. Maybe it's a matter of wear and tear over time being greater because your average speed is higher? I have a hard believing it's the added weight of the motor and battery either since I'm 50 pounds heavier than my brother in law and we have swapped biked a few times with neither bike having issues.

It can actually be much worse and void your insurance.

There are kits available to convert a low performance e-bike into a high performance one, which runs much faster and needs a registration and a number plate.

But cause an accident, which doesn't even needs to be your own fault with such a revamped bike and your insurance will tell you that you're shit out of luck and you will have to pay for the whole damage. Potentially ruining your life.

Also, at least in the UK, unless the e-bike meets certain conditions it is legally a motorcycle - which comes with the requirement for a licence, insurance, vehicle approval etc.

https://www.bbc.co.uk/news/uk-england-london-51707616

Yes this is a better link.

https://www.gov.uk/electric-bike-rules

Yes, another important one is the chain, if used for transmitting motor power. The additional torque can severely shorten it's life span if it is not adequately strong.

Hopefully your motor will also work as a regenerative brake. But perhaps not every controller offers that?

As I understand it, that's actually rare.

It is. Motors that can regen also 'cog' if you're out of power, which sucks. It turns out it's a lot more comfortable to just have a freewheel system that can coast without any extra friction. The extra energy recoverable otherwise just isn't worth the tradeoff.

It should scarcely cost any power to cancel the cogging torque though, wouldn't it? Can't you just keep a small percentage of the battery in reserve for that purpose?

No matter what you do, you still have the ultimate potential endpoint of being stuck out somewhere with a dead battery pack and an annoying ride home compared to a freewheel system.

(It's worth mentioning that the other main reason you don't see regen used much on bikes is that freewheel systems allow the use of gearing, which greatly improves starting torque, which really is what matters for ebiking comfort. Direct drive systems are less efficient, so they are already starting from behind the curve with regards to making regen worthwhile.)

https://www.bikeberry.com/pages/direct-drive-vs-geared

Not rare at all. Most direct drive motors, which is almost all over 750w, can do it, and their associated controllers generally have a setting for that.

Absolutely. The weight of batteries and increase speed will quickly tell you you need hydraulic brakes, and not a crap system either.

I was thinking, the one in the linked article uses friction against the back wheel. What happens the moment you get a good chunk of debris in there? It could get painful very quickly.

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