40k flat commute @ 40k/hr, Direct Drive or Geared?

General Discussion about electric bicycles.
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hrc   100 µW

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40k flat commute @ 40k/hr, Direct Drive or Geared?

Post by hrc » Feb 16 2020 1:26pm

Hi all, after a great first mid drive tsdz2 build I need to start my second ebike project. (Yes, I'm definitely infected by the diy ebike virus)
I need to build an ebike to commute 40k a day and I want to able to do it at not less than 40k/hr (25 mil/hr) on very flat terrain. I could do that speed on the 750w tsdz2, but it's not the optimal tool for the job (I now installed that motor it on my wife's bike).
Due the terrain is really flat so high torque situations will not happen often
With above goal in mind, I plan to buy a 500-750ish Watt rear hub drive motor, but I'm not sure about what type of motor and brand to buy.
- Would a direct drive be the best choice and make less long term problems? Or nowadays the geared hub motors work well enough?
- Seems a sinewave controller should be a must?
- I guess I should aim not less than 48v/20Ah controller?.
What would the experts recommend?
Important too, I don't want to break the bank and I live in Europe). Thanks!

goatman   10 kW

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Re: 40k flat commute @ 40k/hr, Direct Drive or Geared?

Post by goatman » Feb 16 2020 2:45pm

I can give you an example of what id put into grins motor simulator and rough cad$ price

mxus 3005rc dd hub $225, baserunner controller $250 and 16ah battery, I think spokes,rim laced to motor $200 maybe more and statorade $35

the 3005rc is a fast wind for a smaller 20 inch rim, not so much torque although it should get the speed you want on the flats and id be thinking of going to 52v. mxus has a 3006?rc same motor but wound for a 26 inch rim

baserunner is waterproof around 35amp max and fits in the base of those hailong type batteries

if you got something like that from grin technologies it would just bolt onto the bike, plug it together and go without having to figure anything out.

im not sure if the baserunner controller has an on/off switch but if the battery has an on/off switch that would turn the bike on/off.

kdog   10 kW

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Re: 40k flat commute @ 40k/hr, Direct Drive or Geared?

Post by kdog » Feb 16 2020 3:46pm

I'd definitely be thinking dd hubby for efficiency, quietness and extreme reliability. I've done <8k Kms on several of mine (9c, lellie )and never touched them once. I love regen (hills), but it might not be an issue for you.
9c is a great choice for a basic hub. 8turn in a 26" wheel will get you 40kph at 48v. Will run at 1000w all day without hearing up too much.

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dogman dan   100 GW

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Re: 40k flat commute @ 40k/hr, Direct Drive or Geared?

Post by dogman dan » Feb 17 2020 8:17am

DD, not so much for durability though, but for the quieter operation at speeds above 15 mph. At 40 kph/25 mph, a geared hub can get just a bit noisy, especially later on after it slings some of the grease off the gear surfaces.

Not a lot of hills to coast down, so the better coasting of the geared hub matters less.

DD will be heavier though, so if weight is important, go geared. But,,, you are going to carry a huge battery anyway, to ride fast for 40 k, so the bike won't be light in any case. 48v 20 ah battery to run that fast, that far.

Just about any dd hub of the 500w rated type ( like in the typical 48v 1000w kits) will do fine for this, unless you weigh 300 pounds or more. If that is the case, then a geared will be even more overloaded.

With 48v or even better 52v, your speed will be just about what you want. a bit faster at first, a bit slower towards the very end of the ride. But 40 kph average not counting stop signs should be there.

Tommm   10 kW

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Re: 40k flat commute @ 40k/hr, Direct Drive or Geared?

Post by Tommm » Feb 17 2020 9:23am

You want about 1.2kwh to do it smoothly without pedalling. Pedalling, about 800wh. This is with 20-90% charge cycle.

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dogman dan   100 GW

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Re: 40k flat commute @ 40k/hr, Direct Drive or Geared?

Post by dogman dan » Feb 19 2020 8:44am

yeah, 1000 wh battery never really puts out all 1000 watt hours, out on the road. Charge to 100% if you will regularly discharge below 20%. 20 to 90 ideal, but nothings ideal in real use practice. Cold ass day, you will have to charge to 100% and discharge deeper, because your power went to warming up the battery when you started to ride.

800 watt hours used is about right, on average. You'd be pulling 800w for about an hour.

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