Building an EV more efficient than walking

[Saladin]

In the immortally sage and oft overlooked words of Colin Chapman "Simplify then add lightness."

What's more efficient than walking?



Do I need 2 tons to relocate a 80kg payload (me)?

I'm building a car killer. In fairness my car's mostly dead from neglect anyway. I'd fix it except if I did that I'd probably keep driving it.
Besides bikes are better.

Here's one I built earlier.



Two motor upgrades, 7 tyres (5 rear 2 front), two wheel hub rebuilds, one groupset, several drivetrains and 5500km later she's evolved to this.



2.25kWh, 2 horse power, and a throttle only range of 80km at 45kmph. If I quoted pedal assist it'd be inifinte for obvious reasons.
You can't buy an eMTB this capable.

Latest project is a cargo. It's stripped down at the moment.



...any wifey is away so bikes in the kitchen are kosher.

I spent yesterday building a towbar from an old quick release axle..



I thought it'd be cool to pull her own support vehicle. ..err...yeah....that needs a MKII the centre of gravity on the 25kg "trailer" is too high and unstable.

I've a kiddy seat and a roll-cage for the front.

Also a 3.5kVA case-mount



..and a downstream welder..



..and an induction hob..because I like vehicles than make coffee and bacon butties

Plan is fit a progammable mid-drive motor with 160Nm of torque.
Upgrade the groupset.
Bigger tyres for suspension.
Suspension saddle.
Suspension seatpost.
Integrated lighting kit with indicators and stop lamp on manual and light sensing controls.
Dual batteries: 52V 2kWh (combined): which can be plugged into the MPPT solar controller on the genset for more genset capacity or the genset can charge the bike on the fly for extended range, and I can enable VTG if I synchronise the genset to another microgrid or utility network and enable backfeeding allowing both the genset and/or the bike battery to contribute power to the network or micro-grid.
Third battery e-bike integration facility.
Spare tubes + toolkit.
First aid kit.

[Joeboy]

An interesting post Saladin. Will the cargo be used for delivery or personal use only?

The induction hob takes it into motor home territory.

[AGT]

Welcome to the forum.

[Krill]

The cargo bike looks ace, especially in the yellow.

[John_S]

Pity that it is totally illegal on UK roads, bridleways etc. Too high a max speed. Too much power.

[Saladin]

Thanks for the salutations AGT!

It's a car delete kit Joeboy. I'll be using it to transport me and anything I can't fit on my hardtails in a set of paniers. The genset is to power event and site builds because production companies are finally realising that running 100kVA gensets for the week prior to an event to charge a dewalt battery or two has decimal efficiency. I've used it to power stages too. It can synchronise to the input and augment the output. ie. It'll take a 3.5kVA input and output 7kVA if the battery has enough juice or the duty cycle accommodates it. I have some jobs coming up too that I'll need to take the client's installation offline to work on it so having redundancy power in the toolbox for them and my tools is very handy.
I also see potential for the welder when mates break their tie rods off-roading in to boonies.
I live in hill country and I've been towing my 9yo son up climbs on his bike to go adventuring. Having the childseat and a rollcage means I can take him further and higher. You can really enjoy a unique perspective of the civilisation we've built looking over it at 600m above sea. ...and then you can bomb it back downhill (on a regular MTB) ...great craic...seriously hard to get anything done. Less is more on that front, at least I'm not making it worse.

The genset can form and/or integrate to a micro grid for when SHTF or people reasile that decentralisation or stand alone networks and have massive benefits. The practical limt of solar array size for it is ~1500W in standalone. I've plugged 3000W sunny boys into them though which works fine AC coupled with frequency controlled throttling.

It's not at all illegal John S. It can be electronically resricted on the console display to your preferred threshold and feel free to get a license and insurance for a moped to tick all the boxes. The kits come with these stickers too.



Muscle bikes can do 80kmph. I know this because I've done it. However a 250W motor won't pull any significant payload up a hill at any signifcant speed. As far as I know there's no torque limit in the definition of a pedelec.

I'll be putting mirrors on it too...I forgot to mention that.

[John_S]

I stand corrected. I can now see that it is not illegal if you register and tax it as a moped/motorbike.

Having been hit by a cyclist at a pedestrian crossing, I am fully aware of the additional risk of injury to pedestrians with the extra weight of a bike in your configuration.

[Saladin]

{Moving this comment to it's own box because twas not I wrote it. I'm guessing it was an entity with Moderator powers mistakenly hitting edit instead of quote?...}


"I look forward to hearing what sort of load it can pull. I use my Dahon Vitesse overseas to transport a slab of beer on the rear pannier (up from the shop, not general cutting about everyday use). In 40+ degs its a godsend. Its just a foot crank 5 speed but gets the job done. I had hoped to find an inexpensive front wheel drive kit running on the rim but they don't seem to be going about."


Hoho me too. It's not aways about power. The low speed gear is 1:1. In terms of climbing 40° slopes in 15°C heat with the hardtail eMTBs the weakest link tends to be me as the weak link between pilot, traction and power is pilot. The powertrain will be the same.

[Saladin]

I stand corrected. I can now see that it is not illegal if you register and tax it as a moped/motorbike.

Also not illegal off-road. Possibly not illegal under common law for non-commercial activities.
Personally I don't believe in putting a price on health nor do I think that in the absence of coercion and accountability forsaking morality and conscience is acceptable. I fully accept that this is not a universally held policy and no solution is ever perfect. Pity universal healthcare's less of a priority than inequality amplifiers.



There's less convenient ways to restrict the machine. You can do it with gearing. A small chainring will limit top speed because the motor has an immutable RPM limit. You can also override the display console speed limit by programming the motor controller with a laptop and telling it to ignore user speed limit changes. The third option is to forget the password to that menu and lock it out forever more.
The difference between the higher output motors is also how much it bogs under load like hills. Think of it like oversizing a solar array if you will.

Using a current limit is waaaay smoother than a speed limit because the motor runs at continuous output instead of surging according to wheelspeed.

If one was to get really pedantic about EU regulations a Pedelectric motor is constrained to cut power proportionally to not assist the rider above 25kpmh. This of course means that gravity assisting you to 80kmph on a vehicle with a restricted motor is perfectly legal.

Having been hit by a cyclist at a pedestrian crossing, I am fully aware of the additional risk of injury to pedestrians with the extra weight of a bike in your configuration.

I'm very sorry to hear it. Were you hurt? What was the outcome?
I tend to avoid urban centres, I save being reckless for the wilderness. I bias being the victim over an innocent, skater dicipline I guess.
Every bad actor makes becomes a negative ambassador, if people want to be free we have to have respect. I wonder why we don't need licences for horses?..

[Saladin]

Drivetrain

There's a rumour that mid-drives destroy drivetrains.

I've no idea what they're talking about.
I mean all you gotta do is learn to use your transmission properly.

You might have to feed the learning curve a few chains and cassettes...



...that's about 8000km worth of chain...

Your mileage will vary. I just consider it a fuel cost and materials for some garden art or forging project.
Half of that was neglect, abuse and ignorance until I learned how to maintain them.

Not all chains are made equal. I've destroyed Amazon "Shimanos" in 100km. The most durable seems to be KMC e-bike rated at 600km of what I've tried. These can be found discounted disguised as Decathlon e-bike chains.

The 11 and 13 tooth gears are downhill only 15 tooth is flat ground only. After you destroy sprockets from using too much torque in too high a gear you can use the limit screws on the derailleur to soft delete the expired sprocket because the chain will start skipping over the teeth in short order after it's abused.

In terms of drivetrain longevity. Don't bother with spendy lightweight aluminium. You want steel and unibody casettes.



Shimano Linkglide is souper tough...and completely incompatible with everything else...
The Deore mech is a boss. The CUES mech is compatible but lighter duty, more exposed, lighter clutch and chain drops pretty frequently if you're sending it.
Stick with 9 speed because you have motor assist and you can double your cassette cost for every gear after that.
All linkglide groupsets use 11-speed chains.



Clean the drivetrain after every ride. Apply lube to every link top and bottom (you want it to migrate into the roller pins) and allow the lube to soak in overnight if possible. Wipe off excess before you venture off to avoid dirt getting attracted to it. It's only the pins you need to lubricate, nothing else; it's all incidental.

• Dry lube: light, low viscosity, doesn't attract dirt (because dirt wears chains..think grinding paste), vanishes first sign of water.

• All weather: for light rain with low road spray. More persistant compromise between sticktivity and dirt accumulation.

• Wet Lube: Heavy oil like for a chain saw. Works in the wet. Don't use it in the dry or off-road.

• Wax: The best...except zero rust protection and water soluble..so fair weather only but much cleaner and better at protecting.

I ride in all conditions and usually a ratio of 7:3, asphalt:gravel. I also tend to not spare the horses. The rider can contribute another horse power in short bursts on top of the motor. Which is to say most peoples' drivetrains ought to last about 3 times longer, especially if it's all road use, in the dry, at low power levels.

Hub drives are much more forgiving aaand some can regen..not that' I'd use that feature because my brake pads last an awful lotta kms...but you gotta go to 3000W to climb the same hill a 500W mid-drive can.