suggested second hand speed pedelec?

[frugal]

Hi!

I've been lurking here sporadically for a year or two, but this is my first post. Please bear with me.

I'm looking for a safe, maintainable speed pedelec with as low a lifetime cost as possible. That's the important bit I guess.

Some less important bits, in random order...

To get to work, shop and friends a few times a week. I have some experience with 30km one way on a 25km/h ebike, and that tastes like more. My best client is over 60km away. I rented a local shop's dual battery bike to get a feel. No hills, but it took me an hour and 45 minutes. Batteries were nearly empty by the end of each leg though.

I'm absolutely allergic to manufacturers deciding what I can do with my things. I've heard horror stories about ebike batteries refusing to work because they need to be blessed by a mechanic or the manufacturer. Not with my bike. Forget it.

I've also heard and read a bit about absurdly strict EU rules. I'm fine with ignoring these as long as it's safe. As long as I don't get into expensive trouble with insurance or police.

My bicycle repair skills are limited, but a good friend has been tinkering with mechanical bikes since the age of six. He's very much willing to help on anything mechanical.

Electronics and software don't scare me. I enjoy them. I play with those all the time, as long as it's free software.

How would you tackle this? What type of motor would you use and why? Questions! Questions! Questions!

frugal

 

[amberwolf]

Some questions and thoughts below to narrow down specifics to help choose a bike, and system, etc.:

I'm looking for a safe, maintainable speed pedelec with as low a lifetime cost as possible. That's the important bit I guess.

Safe may need defining to ensure you get what you need: what specifically needs to be safe about it? No risk of battery fires? No risk of injury in a crash? Great braking? Great traction? Handling? Etc?

Some things you may not get in combination with each other, depending on budget, weight limits, size, usage, riding conditions, bike type, etc.

To get to work, shop and friends a few times a week. I have some experience with 30km one way on a 25km/h ebike, and that tastes like more. My best client is over 60km away. I rented a local shop's dual battery bike to get a feel. No hills, but it took me an hour and 45 minutes. Batteries were nearly empty by the end of each leg though.

Knowing the capacity of the batteries, the speed travelled at, actual distance travelled under what road and wind and terrain conditions, etc., you can work out what your wh/km was and what it will be at a faster speed (assuming you need to take less time for the same trip). This will help you make sure you get a big enough battery for your worst-case needs (I'd also recommend adding 25-50% to the worst-case estimate to allow for detours, poor conditions, and aging of the battery.

I'm absolutely allergic to manufacturers deciding what I can do with my things. I've heard horror stories about ebike batteries refusing to work because they need to be blessed by a mechanic or the manufacturer. Not with my bike. Forget it.

That's a good way to make sure you can maintain a system. It does usually mean more work to integrate everything in the beginning, but leaves you knowing everything in it and how it's connected and needs to work together, making it easier to troubleshoot (and fix) later. Probably will cost less, too, for the same capabilities.

How would you tackle this? What type of motor would you use and why? Questions! Questions! Questions!

That depends on your budget, bike type, riding style / needs, riding conditions, etc.

Some thoughts:

For ease of maintenance and reliability, a DD hubmotor is better, but makes for a weaker wheel, and is heavier and less efficient under some conditions, like stop/start traffic, slow non-flat riding, etc. Usually needs a bigger controller and more capable battery to do the same job in those conditions.

A geared hubmotor might be lighter / more efficient for some usages, but has more wear parts.

A middrive is more capable of being efficient in more riding conditions, but is a lot less potentially reliable, has more stuff to fail between motor and ground, and more wear parts than either of the above.

Friction drive could be even smaller and lighter, but is useful under less riding conditions and requires more frequent maintenance depending on design.

 

[frugal]

Thank you amberwolf for your suggestions!

Safe may need defining to ensure you get what you need: what specifically needs to be safe about it? No risk of battery fires? No risk of injury in a crash? Great braking? Great traction? Handling? Etc?

All of those, to the extent they don't overly impact the budget. Def not haggling with myself on braking.

Knowing the capacity of the batteries, the speed travelled at, actual distance travelled under what road and wind and terrain conditions, etc., you can work out what your wh/km was and what it will be at a faster speed (assuming you need to take less time for the same trip). This will help you make sure you get a big enough battery for your worst-case needs (I'd also recommend adding 25-50% to the worst-case estimate to allow for detours, poor conditions, and aging of the battery.

That puts me at 1.5-1.9 kWh in battery capacity.

That's a good way to make sure you can maintain a system. It does usually mean more work to integrate everything in the beginning, but leaves you knowing everything in it and how it's connected and needs to work together, making it easier to troubleshoot (and fix) later. Probably will cost less, too, for the same capabilities.

That philosophy has become the rule for me, not just for bikes.

For ease of maintenance and reliability, a DD hubmotor is better, but makes for a weaker wheel, and is heavier and less efficient under some conditions, like stop/start traffic, slow non-flat riding, etc. Usually needs a bigger controller and more capable battery to do the same job in those conditions.

Thanks to you, I know I need a direct drive hub motor.

So second hand, safe, direct drive hub motor, 1.75 kWh battery capacity and maintainable.

The bike itself. Major brands are out. Locked, expensive or both. Yay! I've cut my options down to under 5% of the second hand market already. Easy. Or difficult. Depends on who you ask.

The motor. No Bosch. And maintainable. I heard Bafang is slightly better? Are their hub motors maintainable? What if my second hand one breaks? New ones are CAN, old ones serial. Can I replace old with a new? Is replacing with scoured old my only option?

1.75 kWh battery capacity does not come with used bikes. I need new generic ones. Recommended models or sellers in/to the EU? Safest and easiest to mount in the frame's triangle, dual drink bottle style?

Lots of questions to your answers.

frugal

 

[amberwolf]

Probably it would be best for your purposes to avoid any prebuilt ebike, and just build one around a regular bike that already does the things you want other than not having a motor to help you ride.

There are dozens to thousands of options for converting an existing bike, depending on your requirements and limitations.

There's two ways to proceed with that: Pick a motor/controller/battery setup that can do the work you need, then find a bike it will fit on that will physically do the things you need to do, or pick a bike that does what you need, then find a motor/controlelr/battery that fits on it and does the work you need.

There's probalby going to be some compromises here and there, but since safety while riding is a concern, I'd pick a bike that can do all the stuff you need first, and then we can figure out how to convert it to electric.

If you need up to 2kWh of battery, that's a pretty big pack, physically--it could weigh 10-15kg and be the size of a decent stack of hardback books. If that is only for occasional long trips, and you can use half that (or less) most of the time, you can setup a main pack mounted more or less permanently to the bike, and add-on packs (panniers, etc) as needed in parallel to that, or simply switched to when the first runs out.

I don't know that you can fit that much battery in a couple of bottle-style packs--those are typically very small and low capacity.


For brands, if you are looking for a DD hubmotor, it doesn't really matter--they are all virtually the same for the under 1kw motors. The wheels they usually come in, regardless of brand, are not usually built that well, with cheap rims, and usually use the wrong size spokes (too thick), so I would reocmmend ordering your own 14-15g spokes and nipples to build the motor into a rim of your choice, even if the motor already comes built into a wheel.

There are many kits with controller, motor, and accesories (throttle, pas, display, ebrake levers, etc) that are quite cheap and "maintainable" in that you can just replace parts as needed, more or less, with other "generic" parts (some things can be fixed but many have to be replaced if they fail).

Or you can buy each part separately to get specific functions and features you want, or particular styles or qualities you want them to have.

I recommend defining the specific things you want the bike to do for you and how you want htem to work, to figure out if a kit will work, or if you need to get specific parts to do those things.

For instance, do you want throttle only, or PAS only, or both? (presumably as a pedelec you do want some some form of PAS control). Do you want torque-controlled PAS? or just cadence-controlled? Do you mind it only being on/off (meaning, the PAS just turns the assist on at whatever level you have chosen at that moment, when you are pedalling, regardless of how hard or fast you pedal), or do you want to actually have control over the motor power by how hard or fast you pedal?

Most systems with PAS are only that on/off type, some have a throttle override that gives you direct control, some don't...but you can use a throttle-only controller, modulated via the Cycle Analyst from ebikes.ca, to have pretty much any kind of PAS control you would prefer; for example, I use the CA to control the speed of my SB Cruiser trike via pedal cadence).

 

[amberwolf]

Batteries...safety is relative, since all batteries have the potential for catastrophic failure under the wrong conditions.

The safest batteries are built from good-quality well-matched cells that are used within the middle of their capabilities, not pushed to their limits.

Longer lasting batteries (that stay safe for longer) are not discharged to empty or charged to full (but this means a battery significantly larger and heavier and more expensive than otherwise for the same usable capacity).

Cheap batteries wont' be any of those things, and most batteries are cheap batteries. I don't know where to buy batteries made of well-matched cells, other than modules from used EV battery packs, that can then be tested and reworked to wire them up to work as an ebike pack, adding a BMS if needed / wanted, and putting into whatever casing is needed for the riding and weather conditions you have.

While none are perfect, some manufacturers have been shown by experiences of various people to make good packs, like EM3EV. Most of the better manufacturers are going to cost significantly more for what seems like the same thing from cheaper places.

 

[frugal]

Probably it would be best for your purposes to avoid any prebuilt ebike, and just build one around a regular bike that already does the things you want other than not having a motor to help you ride.
...
There's probalby going to be some compromises here and there, but since safety while riding is a concern, I'd pick a bike that can do all the stuff you need first, and then we can figure out how to convert it to electric.

My risk tolerance dictates me to get a licensed 45km/h bike used, then start tinkering. I'm in the EU. If I ride into someone at 45 km/h with no license plate on my >25km/h ebike and cause serious injury, I am done for. My insurance will never pay for that.

A license plate lowers that risk of my insurance not paying for third party injury to a point I'm comfortable with. Most diy changes to the bike are illegal in the EU. An extra battery pack or a similar motor? Super low chances insurance would even look into that, let alone notice. There's no technical inspection. There's no public spec sheets saying what component goes on what bike. That holds even less for licensed bikes with an older type approval. There's plausible deniability for changes if I got mine second hand.

If you need up to 2kWh of battery, that's a pretty big pack, physically--it could weigh 10-15kg and be the size of a decent stack of hardback books. If that is only for occasional long trips, and you can use half that (or less) most of the time, you can setup a main pack mounted more or less permanently to the bike, and add-on packs (panniers, etc) as needed in parallel to that, or simply switched to when the first runs out.

I don't know that you can fit that much battery in a couple of bottle-style packs--those are typically very small and low capacity.

So two generic batteries, 850W or slightly higher each. In Hailong or similar packs. This allows me to do my longest rides with two, but avoid some serious weight on shorter rides. Preferably connected in parallel for long rides, but even switching will do.

For brands, if you are looking for a DD hubmotor, it doesn't really matter--they are all virtually the same for the under 1kw motors. The wheels they usually come in, regardless of brand, are not usually built that well, with cheap rims, and usually use the wrong size spokes (too thick), so I would reocmmend ordering your own 14-15g spokes and nipples to build the motor into a rim of your choice, even if the motor already comes built into a wheel.

There are many kits with controller, motor, and accesories (throttle, pas, display, ebrake levers, etc) that are quite cheap and "maintainable" in that you can just replace parts as needed, more or less, with other "generic" parts (some things can be fixed but many have to be replaced if they fail).

I realise that there's quite a bit of interdependence on parts from the same kit. Anything that increases my chances of being able to change a broken part without the rest of the kit? Changing the controller for example without changing the display? Or changing the motor without changing the controller?

Or you can buy each part separately to get specific functions and features you want, or particular styles or qualities you want them to have.

I recommend defining the specific things you want the bike to do for you and how you want htem to work, to figure out if a kit will work, or if you need to get specific parts to do those things.

For instance, do you want throttle only, or PAS only, or both? (presumably as a pedelec you do want some some form of PAS control). Do you want torque-controlled PAS? or just cadence-controlled? Do you mind it only being on/off (meaning, the PAS just turns the assist on at whatever level you have chosen at that moment, when you are pedalling, regardless of how hard or fast you pedal), or do you want to actually have control over the motor power by how hard or fast you pedal?

Most systems with PAS are only that on/off type, some have a throttle override that gives you direct control, some don't...but you can use a throttle-only controller, modulated via the Cycle Analyst from ebikes.ca, to have pretty much any kind of PAS control you would prefer; for example, I use the CA to control the speed of my SB Cruiser trike via pedal cadence).

My budget dictates me going for the cheapest legal technically safe option. It's also why I'd like to stay as close to the existing speed pedelec as possible for now with the exception of good quality batteries.

From what I've learned, here's what I'm looking for in an existing speed pedelec:
- standard 135/138mm rear dropouts. This helps me get a new motor in should I need to replace it.
- 500W or higher direct drive rear hub motor, decent quality Chinese. This should be fairly low-maintenance, except worst case some respoking
- good quality brakes - hydraulic disc. Almost all speed pedelecs have them.
- an existing cheap King-Meter or Kunteng Chinese display . This often indicates a simple controller.

And motors... I see so little info guess recent Bafang rear hub motors are out because they speak on a CAN bus only and will only speak to Bafang controllers? Or am I mistaken about that? Does that also mean they won't speak to generic batteries anymore? You seem to suggest the alternatives, like MXUS or Shengyi, are pretty ok too? I guess these are not as locked in as the Bafang ones?

frugal

 

[AGS]

Bafang rear hubs are fine and will work with a variety of controllers and batteries. The M620 mid drive is the one to stay away from because it has been developed for manufactured bikes.

You have to be careful when choosing a display to ensure it is compatible with the controller that you are using. Kunteng (KT) displays and controllers are highly regarded.

And some thought needs to go in to what battery and controller to buy that matches the motor. The battery should be a slightly higher rating than the maximum output of the controller and the controller should be rated at slightly higher than the motor.

The trouble is the motor ratings are all over the shop depending on the market they are supplied to. A 250 watt rated motor in Europe can be exactly the same as a 750 watt rated motor in the US. So if you buy a battery and controller that is just sufficient to run a motor at 250 watts, they won’t have enough output to run that motor at 750 watts.

For my Greaser build I chose a battery and controller that are both capable of running a 1500 watt motor, even though the EU rating for the motor is only 250 watts.

The work around for the 250 watt law in Europe is to ensure that you use a motor that has a 250 watt rating, even though you know the motor is capable of taking much higher power. And then setting up the display so you have the option of choosing a setting that keeps it legal. You can’t get away with having a dedicated switch for road/off-road.

Prebuilt legal ebikes work on the same principle. Their 250 watt rated motors are capable of running at much higher power and the manufacturer locks the display and chooses a battery and controller accordingly. So you can’t adjust the power to the motor because the display is locked and the battery/controller combination won’t supply the motor at high levels.

 

[frugal]

Bafang rear hubs are fine and will work with a variety of controllers and batteries.

Does that still hold true for recent can bus based ones though?

On the Bafang website, I can find exactly two very closely related types that should work for me without too much fiddling:
- H640 RM G0900.750.C/DC 零部件
- H640 RM G0900.750.D/DC 零部件

For both, it's not clear if they're direct drive. Probably geared, given the 80Nm torque. Which is bad for my use case of long flat stretches.

For MXUS, it seems like I'd want the MXUS DDR-40 1000W. Not on Aliexpress, but shows on alibaba. Mxus Ddr40-27h 36v/48v 350w--750w E Bicycle Brushless Dc Motor Kit - Buy 36v Brushless Motor,Electric Kit,E Bicycle Motor Product on Alibaba.com .

For Shengyi, it seems like I'd want the Shengyi DGW29 750W direct drive Shengyi DGW29 750w Electric Bike Rear Hub Motor For MTB . Not on aliexpress either, but on Alibaba: Shengyi Dgw29 500w/750w Hub Motor Kit Bicycle Mtb Rear Drive Motor - Buy Mtb Rear Drive Motor,Motor For Electric Bicycle,Hub Motor Kit For Ladies Bicycle Product on Alibaba.com .