rear geared hubmotor advice sought

mi7d1

100 W
Joined
Jul 12, 2007
Messages
169
Location
Portland, Oregon
Well it's been several months since I've posted to the forums. I had a 408/4012 rear hubmotor installed in my velomobile but removed it due to some perceived limitations. With the c-lyte motor and 48v 18Ah SLA the weight bothered me. I was able to obtain my desired range of 26 miles on a single charge with an eight or so hour recharge but that was really taxing the SLAs. Fearful of rear wheel problems such as a flat or spoke breakage I removed the hubmotor. I thought about going to a chain drive system. That was ruled out due to increased interior noise. I've toyed around with a push trailer. It works well and can be removed in a mater of seconds so I have a pedal powered only velomobile. I'm not entirely happy with that setup and have decided to go back to a hubmotor.

One of the problems I had with the c-lyte setup was the coging. My velomobile can coast very well. The motor coging was slowing me down and I also feared the voltage that was being generated back through the motor controller into the batteries would/could damage the motor controller.

I'm thinking of trying a rear geared hubmotor now. I'm also going to change batteries and go to Lithium system. I haven't figured out which batteries to use yet, ping batteries or the ones GGoodrum is associated with. I don't know if GGoodrum battery system is ready yet. Anyway back to the geared hubmotor. I need a rear hubmotor because my velomobile is a tadpole style trike. I have a 26" rear wheel and the two front wheels are 20"

I'm looking for a rear geared hubmotor that can take at least a five speed freewheel. From what I'm reading the "new" Puma motor can only use a single speed freewheel or perhaps a three speed, I don't know, I'm confused. The rear dropouts are 135mm on the velomobile. I'd also like to not be limited voltage wise 36v-72v would be ideal.

I have a couple of other recumbents now so the velomobile would be used for commuting purposes mainly. I'm hoping to get going on the refitting in a few months.

Any advice on batteries or drive system would be appreciated.

Thanks,
 
I'm sure the Puma would meet your needs, but I run the 408/4012 as well, and after much testing, foun d the cogging effect to effect rolling efficancy very little. Infact, in the process I found that the brand of tires had a bigger effect on rolling resistance than the cogging effect. My specalized armadillos roll better than the Kenda tires I had by a wider margin than the diffrence between the 408 and no motor at all.

However, a Velomobile is a diffrent animal, so YMMV. I did discover that the effect of the cogging was greatest on the 4012 setting, less on the 408, and nearly non exsistant when the motor select switch was set to the off position between the motors.


But if you do go with the Puma, I know someone who might be intrested in that motor :D
 
Overall I was pleased with the 408 and didn't like the 4012 mode. While running the 408 my maximum speed was 22mph unassisted. With peddling I could cruise at 27mph. There is one hill on a bike route where without the motor I can coast to speeds in excess of 44mph before applying the brakes. I fear going faster due to the narrowness of the bike path. With the motor I could only archive 40mph and not have to use the brakes at all. Granted the tires were of different manufactures. I hadn't thought of that. In addition from what I recall my WattsUp meter was reading well above battery pack voltage, while coasting down that hill.

It's my understanding that a geared hub motors don't have regen braking hence no cogging, weigh less and would coast better. What confuses me is that I can only find two motors. The Puma, which as I read is better but can only use a single speed freewheel on the newer models. The other is from texaselectricbikes.com and all they call it is a Geared Brushless Hub motor. On the picture it says BMC on the side cover. That is where the confusion arises. I read of BMC/Puma's. Is this BMC an older version of a Puma? Were they the same motor?

What I'm after is a system that'll push me to the mid to upper twenty's unassisted runs at 48v and can handle the hills in my area. Sadly, I do have a motor that according to the simulation will do that. It's a 406/409 but it is a front wheel motor and I need one for a rear wheel.
 
I hadn't tested the cogging effect at those speeds, all my testing was done under 20, But I ride the bike often with no power, just as a normal bike and its never been a problem. It might be a factor at 40, sounds like you were losing about 10% but that is probably mixed with tire brand too.I bet if you had switched the motor to the neutral setting, you would have cut that braking effect in half at least.


For top speed, the Puma is slower than a 408, but will climb hills better. Its a BMC geard hub motor, but with a few tweaks. They are only sold in europe. the one at Texaselectricbikes is just the BMC geared hub motors.

To get into the mid to upper 20s and still be able to climb hills, you're going to need more voltage. a 406 or a 407 would get your speed up, but lose more speed on the hills at 48V. A Puma would probably do it at 66 volts.
I'm running my 408/4012 at 74V, and the 4012 does 25+ pretty easliy, plus it maintains fairly well on the hills. the 408 I rarely use at 74V, but I can hit 35, and this is on a mountianbike frame with 700c wheels. a full fairing velo should do better
 
Actually the Puma comes in 2 "flavours", one a 260RPM@36v, the other 320rpm@36v. The faster one is spins faster than a 408 I believe..
The built in freewheel does a great job, and the difference over an x'lyte in cogging is very noticeable, especially on a low drag vehicle.
The Puma has been reworked over the BMC, and has several upgrades. Amoungst these, are fatter phase wires, and a welded pinion (that very occasionally would slip on the bmc). If you need more than a single speed freewheel, it is hoped that the next batch of Puma's will have the option.
The faster Puma would probably manage decent hillclimbing and over 30mph at 48v, but does feel a bit "crisper"at around 60v+.

Hope this helps:)

Steve
 
Thanks everybody for the input. My velomobile weighs in at 77lbs (35KG) as I ride it. With the c'lyte setup I was using it was around 143lbs (65KG) At about 18mph (29kph) the aerodynamics come into play and the trike becomes one of the most efficient pedal vehicles around. 100w will keep it just above 17mph (27kph) This is without the additional weight of e-assist. With the weight of my previously installed c'lyte and SLA system 100w would only get me 15mph (24kph) Since the bike weighs so much it is difficult to pedal if needed and I would also be fighting the cogging and back EMF. My motor controller is just out of my reach unless I'm at a stop.

At the moment it seems that the Puma is the way to go power and torque wise. However since I'm not looking to purchase until after June I can only hope that a newer multiple freewheel system will arrive. I'm not holding my breath. If the worse happens I can use the BMC geared system.

Thanks once again,
 
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