looking for ideas for an Ebike build

saintex

1 mW
Joined
Jul 10, 2016
Messages
10
Location
North of Montreal
Hello All,

I have extensive mileage on a regular road bike with some mtb in summer and winter.

I'm looking for something that will let me go further and faster on trails. So Ideally I would like to be able to contribute SOME watts via muscle/carbohydrate(beer) conversion. Summer and winter on snow.
Is it possible with a single or double chainring and 7-10 speeds?

max speed 55kph
26" wheels fat bike tires
100km range at 40kph
disc brks
85kg rider
mostly flat with short steep hills , sand pit style or gradual medium length climbs.

Vector frame looks to be a good option?
Battery is either 18650 NMC or Pouch NMC 48-72 V with 26-30Ah ?

I can't figure out a hub motor that can do the power AND carry a cassette or freewheel

Looking FORWARD to the DISCussion
 
A lot of big hub motors will do what you want. 1500 to 2000 watts. However, you will need a huge battery. Something like 72v at 25a. That is a very big and heavy battery for a bike. What you are describing is an e-scooter or e-motorcycle.

Have you read this yet?

https://endless-sphere.com/forums/viewtopic.php?f=3&t=66302

:D :bolt:
 
max speed 55kph
26" wheels fat bike tires
100km range at 40kph

More speed = More Battery
More range = More Battery
More Battery = More Money
More Money = More Problems as the gangster wanna beeeeeeezzzzzzzz zay
 
Well, what most of us without mo money do, is adapt somewhat to what our bikes can do. The dream persists, but we learn to be happy enough with moderate performance goals.

A whole lot of newbs want a lot of speed, and a lot of range at that speed. To start with, range in general equals slower, partly because really big batteries screw up the handling of bikes, and because if you slow down to 25 kph, the percentage of the power needed coming from pedaling goes way way up.

But you are a bit different, the top speed you want is not so much, and essentially, if you pedal enough your range is infinite. Some range numbers you see are simply how far you can pedal without much assist at all. But its there when you need it which is perfect.

What you want is going to be found not in a big powerful hub motor, but a decently powered (above 500w) mid drive, fat tire bike. It will have the gears you need, and on the flat should be able to hit that 40 kph you want. In low gears, enough power to climb some dang steep hills too. And lastly, if you want big range, you can pedal it a long ways using a tiny bit of assist, without carrying a stupidly heavy battery.
 
I have shed some baggage, and the ebikes that remain are...1) a fat-tire stretch cruiser (comfort posture) with a BBSHD and a 7-speed derailluer. It has a 30T chainring, so it climbs well. I suppose I don't "need" a 2500W controller, but I have one so when I get some time, I'll install it over the "adequate" stock 1500W unit. I made a DIY toddler seat for my grandson.

If it was stolen and I received an insurance check, I would replace it with the same thing, very happy with it.

The second ebike is a 1500W 35mm-stator rear hubmotor, which runs quite well at 2500W. However, it is almost never used, so I plan to convert the kit to a DIY longtail cargobike. Since the hubmotor is in a 17-inch moped rim, it should climb well, so I will be testing it out on various grades to see where it works, and where it stalls.
 
Lets say I would like 2000w of capacity (range).

thats either 74 Volts at 26Ah
or
48 volts at 40Ah

If I have 26in wheels and would like to have a max speed of 60kph that's about 450 RPM

at 74 volts I would need a 17x7 6kv motor
and at
48 volts I would need a 25x5T 9.03kv motor

Correct?

Is there an inherent advantage to go one way or the other?

Happy Monday
 
Your 2000W is really 2000Wh which is Volts x Ah which is right, 74Vx26Ah or however you want to mix n match. Then while riding you are putting out a certain Wh per distance (miles or kilometers).

Uphill = more Wh/mile
The same with headwind, no pedaling, bumpy rocky vs pavement

https://www.ebikes.ca/learn/batteries.html
Motor Type Rough energy usage
Minimal Assist (using motor only on hills, slower ~30kph setup) 6-8 Wh/km
Typical Assist (~40 kph with pedaling, motor on all the time) 9-12 Wh/km
Power Hungry (either no pedaling, or hauling a load, or going really fast) 14-20 Wh/km

plus a lot more to learn in the heading of the website under LEARN
 
thank you

I was aware of both of these facts.

My question was rather specific, to restate:

Is there an advantage to either motor/voltage setup. I.E. 74V 7T 6kv or 48V 5T 9.03kv
 
markz said:
max speed 55kph
26" wheels fat bike tires
100km range at 40kph

More speed = More Battery
More range = More Battery
More Battery = More Money
More Money = More Problems as the gangster wanna beeeeeeezzzzzzzz zay

the 40t 21700 batteries have got my attention, 20s6p- 72v 24ah 210 amps, 120 cells 17lbs $7=$840
18650 30q 18650 batteries, 20s8p 72v 24ah 120 amps, 160 cells 17lbs $5= $800

the prices are comparable but if you split your packs in 2 parallel halves the 21700 in 3p is 105 amps and the 18650 is 60 amps. 1 pack for quick trips 2 packs for range. if something goes wrong in 1 pack youre done but if you have 2 packs you can still get home on 1 pack.


if I look at the amps and cut that rating in half so the battery isn't working hard that's 50 amps and 30 amps. both seem to be good batteries. 18650 pack is short in length but tall in height. 21700 is long in length and short in height.

I don't know about a 26 inch fat tire doing 40kmh with a 100km range. if im running a 26x3.0 nobby tire it feels like my front brake is on and range goes for a crap so youre going to be pedalling

I like 2 separate packs, you throw 1 in your back pack for range and keeps the bike light.
 
Thanks GOATMAN

I had thought about the back pack idea for keeping the bike light while using my own active suspension for the back pack

I have a chinesium battery source that is roughly half the prices you quote (before shipping) I'm planning to pick them up in china
 
Probably but I was hoping a hub with heavy Duty wide rim with fat tires and suspension would be ok since mid drives don't seem to pack more than 1kW ?
 
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