Internal gear hub vs derailleur @ 2Kw+

amps2volts

10 µW
Joined
Mar 17, 2018
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Thought this would make a good discussion/debate on here. I'm building my first e-bike and can't decide what route want to take for drivetrain. Here are specs of my bike so far.

-Frame: 2009 Trek Fuel EX8 full suspension
-Motor: Mid Drive Cyclone 3Kw from Applied Future Technologies (AFT)
-Controller: Kelly 100amp limit to 60amp
-Battery: Custom Samsung INR18650-35E 51.8V nominal 14s10p
-Other: Cycle Analyst V3

I am considering a Rohloff speed hub 500/14. IGH seems to have many advantages over a rear derailleur. More reliable, lower maintenance, can use stronger single speed chains and higher gearing. But max torque of a Rohloff is 130Nm right around a Cyclone 3Kw motor. So could snap sheer pins in Rohloff. I could use CAV3 to set slow motor ramp up speed. Still sounds risky breaking pins. Another disadvantage seems be that IGH can't have any kinda load on chain when shifting.

So now starting to think a good 7 speed cassette/derailleur with a Wipperman 7E8 chain may be better option. Because seems like that can take more torque. And like 4x cheaper. But chain could wear out/break more frequently because not single speed chain.

What do you all think?
 
I would use the IGH and limit power for its longevity. The controller you mentioned sounds good for the job. Generally speaking limiting some Amps will not decrease top speed as much as limit acceleration. A side benefit is longer run time.
 
The specified torque limit is what you need to respect if you use an internal gear hub.

Indicated wear is where you need to pay close attention if you use a derailleur system.
 
I decided to go with IGH got good deal on a rohloff with external mech $1,000 with shipping.

Think at even 3Kw could handle it. Will find out and report results. Just need program motor to ramp up speed slow. That will keep torque within 135nm/100ft lb. And keep speeds around 45km/h or 28mph its rated contentious max.

Thanks for help.
 
That was not a cheap piece of gear , well you wont be traveling with cluster noise now :D

My front motor maxes out at 60nm you will have plenty of push at 135 threw the gears
 
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