Engwe Engine X

Oldie

Pedelecer
Mar 29, 2013
151
41
Scotland
My 9yr old Claud Butler conversion is still going strong but I now want to add a folding bike for some rural riding - mainly hilly single track roads plus gravel trails. So, I need fattish tyres and a torquey 250w motor (if such a thing exists), mudguards and a rack. My searches took me to Engwe, particularly the 48 volt Engine X, which they describe in the site's embeded video review as having a hub motor which spins 4 x faster than the rear wheel, thus supplying more power/torque than a standard 250w motor (although no torque figure given). Does anybody know what technology this is and whether it's simply a way to disguise a much higher rated hub? The bike also comes with the throttle de-activated. Does that make it UK legal? Apparently the controller can be configured to give full throttle power which I don't want and certainly don't want to be used against me. I do like the design of the bike though and it's likely range.


I also like the C20 Pro (Upgraded Version) which is quite a bit cheaper although it's 36 volt and they claim 25 Nm of torque, which seems a bit low for hill work.


If anyone has knowledge of these bikes, or possible alternatives, then I would be delighted to hear from you.
 

sjpt

Esteemed Pedelecer
Jun 8, 2018
3,818
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Winchester
Most hub motors are geared internally. There are a few direct drive motors around, but the lack of gearing generally makes them fairly inefficient except at high speed, and unsuitable for hill climbing.

I don't know the 'typical' ratio in a geared hub motor, maybe one of the experts will give more info.
One reference says 5::1, (https://www.triketech.com/Drivetrain/PowerAssist/Geared.html) and I see a couple of Woosh conversion motors saying 12.6::1 (https://wooshbikes.co.uk/?hubkits)

25Nm torque is certainly very low. That same Woosh page (scan to 'WHICH MOTOR') shows motors starting at 35Nm, which I don't think they's recommend for your usage.
 
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AGS

Esteemed Pedelecer
Feb 12, 2023
608
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I watched a YouTube video yesterday that made me chuckle when the fella said that Chinese motor specifications are accurate to the nearest kilowatt.

Many so called 250 watt motors are capable of running at 1500 watts if you are sensible with them and don’t let them overheat.
 
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cyclebuddy

Esteemed Pedelecer
Nov 2, 2016
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Beds & Norfolk
The guy presenting that video represents (sells) a number of different brands and runs some of their facebook groups too. He does tend to gloss things up a bit. I took his "spins 4 times faster" to simply mean it's a geared hub against a direct drive - nothing special as such.

The engine-X may have a label saying it conforms to regulations for the UK market, but that it can be speed and throttle unlocked from the menu makes that compliance suspect. Again, to achieve 45kph means the motor is likely either 500w or 750w although presumably marked as 250w to appear compliant (several other makers are doing that too)... but it's all a bit dodgy as to where that sits for legal use on UK roads and public paths/spaces.

A member here did buy a C20 although I don't recall which version. IIRC he sent it back.

EDIT: It was a C20 Pro. The thread is here. It failed with a hall-sensor error and he sent it back in post #42.
 
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AGS

Esteemed Pedelecer
Feb 12, 2023
608
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I’m still trying to figure out if a Bafang SWX02 is rated at 250w, 350w, 500w or 750w. The only difference I can tell between the power ratings of the same motor is what part of the world it is sold in.
 

guerney

Esteemed Pedelecer
Sep 7, 2021
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Do Bafang simply engrave them differently, to suit legality of different regions? This one is marked 36V 250W:



 

saneagle

Esteemed Pedelecer
Oct 10, 2010
6,687
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Telford
I’m still trying to figure out if a Bafang SWX02 is rated at 250w, 350w, 500w or 750w. The only difference I can tell between the power ratings of the same motor is what part of the world it is sold in.
Any motor that is designed for a bike to run at 25 kph is a 250w one, as that's the power you'd be using to ride at that speed without pedalling on a horizontal road. That's why Bosch, Shimano, Yamaha, et al can claim their motors are 250w, yet every couple of years, they make them produce more torque and still claim it's a 250w motor. You know that torque x speed = power, so if the torque increases, so does the power, and today's Bosch motor produces double the torque of their 2011 version 250w motor.

If the motor is intended for a 25kph bike, the manufacturer can therefore rate their motor at 250w and mark it accordingly. How much power it can actually produce in whatever circumstances is irrelevant.
 
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AGS

Esteemed Pedelecer
Feb 12, 2023
608
190
If I didn’t have my Greaser I would be very tempted to buy this. It’s a grand cheaper than a new one. The only thing putting me off is it’s a 750 model rather than a 250. But I’m pretty sure a 250 has the same motor as a 750.

 

Nealh

Esteemed Pedelecer
Aug 7, 2014
20,902
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On the German pedelec forum on eof the guys moded his tadpole trikes bafang swxk to run at some 60 odd volts and 35/40a for over 2000w without issue , though he did use oil cooling.