Building an EV more efficient than walking

[Saladin]

Thx Resy.

Actually the steering damper makes one-handed operation way less sketchy. I'm fine with it now.
There's a much less expensive and neater aftermarket solution here.
As for the big guy upstairs I think my comfort zone to safety margin ratio is a much narrower bandwidth than most.

I thrive in the latter extremes of the B region.



Besides that I'm a pagan, a competent mechanic with highly developed motor skills and heightened perception. ...and I upgraded the brakes..


Suppose a 1000km update is a mite overdue.
It hasn't replaced my hardtail I've 2000km on that since launching the cargo. The hardtail (GT Avalanche 3.0) is just a phenomenal all-rounder it's way more fun, versatile and capable...it also fits on trains.
Both combined have replaced my car.

I've up-speced a few parts since I commissioned the craft.

Starting with the things I got wrong:
The battery placement is not the best. It makes the bike extra bouncy having 15kg of battery in the centre of the chassis. Which affects the handling considerably. I spent a week trying to relocate the batteries I have under the cargo deck to no avail. It's doable if I was to replace the batteries with a different form factor. Given I already have 4 transferable batteries I can't justify the expense of a hardmounted solution.
The compromise I made is that if I'm hauling payload then the weight distribution is normalised by the cargo and the central placement maximises cargo space so moot benefit.
If I have abundant space I relocate 2 of the largest batterys over the front wheel into the cargo area.
Having the 11kg (2kWh) at the front has considerable benefits;
The weight has a lower centre of gravity giving the bike a righting moment (below the bottom bracket) instead of a toppling one.
It keeps the front wheel down on the tarmac giving better traction thus braking effort and steering. It does a lot to keep the front wheel on the ground too on bumpy terrain enhancing handling furthermore as well as increasing the lean angle grip.

The rear tyre is as big as you can fit. If I remove it I have to true it again every time to the tyre not the rim or it will rub. I'm fine with this ( because suspension) but unless you're comfortable trueing wheels then get a narrower tyre.

I managed to shred the 11, 13, 15 & 17 tooth steel rear cassette sprockets on my first 150km fully loaded round trip with a kerb weight of ~170kg through hill country.
Mostly I can attribute this to pilot error (wrong gear uphill & starting) and lack of feedback (motor cadence too high for rider to torque sense).
You have to have mechanical empathy to operate a mid-drive correctly, it's an advanced system compared to hub-drive. I replaced the chain and cassette and used the limit screws to delete the 11T & 13T sprockets since. I now treat the 15T & 17T as downhill gears, the 20T as a level ground cruiser and the 23T as a no-brainer cruiser. Depending on the payload and hill I'll still use the 46T rear on occasion.
I haven't compromised a sprocket since.

In terms of manipulating cadence through gearing; imagine every 10mm you reduce crank arm length by being equivalent to increasing chainring size by ~2.5T.
If you do want to change the gearing a larger chainring increases top speed reducing torque and cadence as well as the increasing risk of motor stalling and FET duress .
Shorter cranks will reduce your torque but enable a faster cadence so arguably with motor assist it enables the rider to augment power at peak RPM so actually increases torque objectively.

I retrofitted a larger lighter 48T Chainring replacing the stock 46T



This improved the chainline and reduced chain dropping because it's got a phancy narrow-wide tooth profile shedding ~0.5kg being aluminium instead of steel.

After a lot of experimentation I settled on a 75mm crank arm set to compliment the motor cadence in the 20T rear sprocket. As a comfortable pedalling speed where I can actually assist the motor on the RPM limit.
The standard length is 170mm. My new cranks are a smaller radius than the chainring. It takes a bittov getting used to but you do and it's more powah = more better.
I added a set of 170mm cranks, a 15mm spanner and a crank puller to the onboard spares because there ain't a hope of moving the bike fully loaded on a hill with muscle alone with those if the motor cr@ps oot.

I'm running the same drivetrain except with 89mm cranks on my hardtail eMTB normalised to the 15T rear sprocket and this works very well.
The ideal would be a torque sensing motor...hard to find and spendy...

I've extended the chainlife by 400km on average by using a genuine KMC e-bike rated chain and splashing out on a CNC machined chain checker that compensates for roller wear.



I switched lubricant to a graphite based one and chain degreaser to eco. Graphite works best for my use case being mixed terrain (road, gravel, field, hardpack, mud, stone...you name it...I'll send it ), it attracts less kruud and it's cheaper than most.

[Saladin]

Other upgrades and Winterising

I swapped the cargo bike pedals for grip taped flats over the pinned ones the bike came with, my feet kept slipping off the metal predecessors when I changed gear rapidly.



They're ideal.

I'm pretty happy with the cargo tyres I fitted to the cargo bike.
1 puncture during hedge trimming season over 1000km

I heart the Magic Mary Rears on my eMTBs and I can't fit wider so there's no point in changing.
2 punctures during hedge trimming season on the same day over 3000km and it was admittedly end of life, so bald there was no centre nobs left and the centre ridge was thinned.

The Smart Sam fronts I was running were removed...I reached the limits of their traction on cold wet asphalt in a lean. I recovered without spilling but decided to go for a higher spec Marathon 365 All Season front and I've yet to get them unstuck since. Lower rolling resistance too.



No punctures after 600km.

I upgraded both bikes to 203mm brake rotors with sintered pads. They stop in the wet like there's no tomorrow.
Sintered pads are a metal composite which can be a bit noisy in the dry but well worth it in the off-season and clamp through mud and dirt.
The most common pads would be resin and meh..yeah grand in fair weather in the wet you need to brake earlier because they have to shed the water and heat the rotor before they bite...you really notice the stopping distance going from one to thuther.
Sure! Sintered eat your rotors faster...meh...cheap part and worth it!

Favourite upgrade?

Can't decide if it's brakes or suspension seatpost + spring saddle combo.

[ivan]

It's also worth noting that electric bikes are more CO2 efficient than people-powered bikes. This is because the CO2 footprint of food is rather higher than electricity, even if it is relatively dirty electricity.

[SporranMcDonald]

It's also worth noting that electric bikes are more CO2 efficient than people-powered bikes. This is because the CO2 footprint of food is rather higher than electricity, even if it is relatively dirty electricity.

I'd be interested to see if anyone has done rigorous and peer-reviewed energy analysis of Human-only versus Electrically-assisted. Which must include the embodied-energy, CO2 and other pollution created by the production of motor & battery & control electronics.

One things seems obvious : It is massively more efficient to travel on a relatively light vehicle, compared to hauling around a 1-tonne or 2-tonne+ deadweight carapace.

[Krill]

Depends on diet. Powering a bike with hamburgers is less efficient than powering it with porridge.

[ivan]

I think all commercially-produced food has a poor CO2/energy rating ie if you could turn fossil-fuel diesel into food, it would be more efficient than growing any commercial crop. Even porridge, Im afraid! The exception would be what is often considered 'third world' agriculture - where human/animal energy is expended for labour rather than diesel+big tractors, no agrichemicals etc. but not much of our food in the 'west' is produced this way.

Yes, there was a proper publication compares CO2 emission of electric bike vs human-powered bike. Unfortunately, I don't remember if they went as far as calculating embodied CO2 and I can't remember where to find it. It was done a long time ago - probably 2006 - 2013 ish

[AE-NMidlands]

Depends on diet. Powering a bike with hamburgers is less efficient than powering it with porridge.

I wouldn't be so sure about that. Animal fat is a very efficient food if you need energy, which is why polar explorers took tallow candles: they can be eaten in an emergency! Paraffin wax wouldn't have done them any good at all. (And pigs are efficient converters of waste food to meat - and presumably fat.)
People with sedentary lifestyles might not need all the energy in animal fat, but I think it was in John Seymour's book "the Fat of the Land" that it was explained that a couple of centuries ago eating lean meat was seen as effeminate, and a slab of cold boiled ham fat on bread was seen as an appropriate meal. A pig was apparently not ready to kill if it could still walk...

All the discussion about vehicle "efficiencies" ignores the public health benefits from active travel, e.g. cycling to a station, or walking to a bus stop then making your own way to the final destination.

[Krill]

Depends on diet. Powering a bike with hamburgers is less efficient than powering it with porridge.

I wouldn't be so sure about that. Animal fat is a very efficient food if you need energy, which is why polar explorers took tallow candles: they can be eaten in an emergency! Paraffin wax wouldn't have done them any good at all. (And pigs are efficient converters of waste food to meat - and presumably fat.)
People with sedentary lifestyles might not need all the energy in animal fat, but I think it was in John Seymour's book "the Fat of the Land" that it was explained that a couple of centuries ago eating lean meat was seen as effeminate, and a slab of cold boiled ham fat on bread was seen as an appropriate meal. A pig was apparently not ready to kill if it could still walk...

All the discussion about vehicle "efficiencies" ignores the public health benefits from active travel, e.g. cycling to a station, or walking to a bus stop then making your own way to the final destination.

...? In the context of energy efficiency from the point the energy reaches the earth to it being used productively to move a vehicle, the diet of the human powering the vehicle has relevance because of the inefficiencies inherent in creating and sustaining biomass at different trophic levels within the ecosystem.

That is to say, it's a more efficient use of the energy which only goes through one trophic level ie grain, than through grass and then a cow. This is the exact logical argument against using e-fuels to power vehicles compared to BEV: the fewer steps the better as each step has inefficiencies. To compare this to the effectiveness of an electric bike charged via, say, PV or a wind turbine, one needs to have all the relevant energy availability and hence efficiency calculations available for the different diets on the one hand, and the different energy harvesting system production costs on the other. And I would dread to think of the different catabolism pathways within the Krebs cycle for working out something like the Atkins diet powering a bike.

Yes, animal fats can be energy dense, (and it was a way to increase the effective food carrying capacity on the boats!) but that has no bearing on the efficiency question that SM raised. It's also not a question of dietary need in the human (humans need protein, QED a hamburger is a decent source of protein carbohydrates and fats which a loaf of bread isn't, but again that isn't relevant to the question raised).

[Saladin]

Hohoho...carrots or cows or photons....d'nay matter. Positive good! Efficiency doesn't really matter if it's fully sustainable. Ram pumps are 10% efficient..self-powered: who cares...

Efficiency matters when the cost is a degenerative effect on our ecosystem. In which case the lowest cost = highest efficiency = good.
It also matters if you haven't got enough.

If my brain uses 20% of my food and I have a good automation idea on a bicycle...


I travel at a 1:6 ratio of muscles:electric. 75% of our lecky is local solar.


...oh dear...couldn't resist buying this..

5" wide fat tyre!



Got it for a steal. Good time of year to buy a bike.
Rebuilt her already. It took 2 days to get the "quick release" front axle out. Original seller lived beside the beach.

New 4 piston brakes and 203mm rotors inbound.
Seems to be indominatable on icy roads.