I'm going to build an ebike and have looked into various motors. I am interested in using a highish torque high rpm motor with a freewheel and a chain drive and and some shifting mechanism of some sort to power the back wheel. I am also thinking about putting on a front hub motor to use on flats. With the two motors I could keep the RPMs in more efficient ranges. I am wondering if adding a front hub motor to the front wheel will add a higher top speed or will it just give me more acceleration. Intuitively, it seems like I would attain a higher top speed but I am not sure how a hub motor would react. Would the top speed of the chain drive and hub motor be cumulative?
Chaindrive + Hub motor combo
- Thread starter AFG
- Start date
dumbass
100 kW
AFG said:
You would really be much better off deciding weather you want hub or non-hub setup. Of course it can be done but it's more difficult to run one of each rather then 2 of the same kind of motor setups. I have always run chain drive system and wouldn't change but that's just my opinion. I am currently running twin motors on my chain drive. To me this is the best of both worlds. If you don't need high speed or torque run 1 motor. If the speed or torque requirement is high pop on the second motor. Works fine for me.
Bob
REdiculous
10 kW
No. If the chain drive is limited to 30mph and the hub can get you to 30mph then your top speed would be 30mph, not 60mph.
Correct. The same applies to hub + chain drive.
Yup. two motors with the same max rpm, torque, and horsepower will just result in more torque.
The extra torque at the torque poop-out zone at 100% of the RPM the voltage will provide you with maybe a mph or two more. But it is far easier to run just one motor that does it all.
The extra torque at the torque poop-out zone at 100% of the RPM the voltage will provide you with maybe a mph or two more. But it is far easier to run just one motor that does it all.
dumbass
100 kW
AFG said:
Actually it depends on your gearing. In my case I have a Nuvinci CVS hub. I could setup my motor gearing so as a single motor would not have enough torque/power to use the max capasity of the hub drive. But with the second motor running it can utilize the full ratio range. This give you the higher speed while also adding additional torque.
In any case..should you select to combine hub and non-hub be sure that the hub motor is freewheeling when not powered. Most are not and some can create a fairly high drag on peddling or the chain motor.
Bob
EDIT: BTW....If a single motor is geared to perfectly handle the load it will generally have an estimated 20% to 25% RPM lose factor. When adding a second motor you reduce this RPM lose factor by lets say 10%. So if your max speed was say 25mph then you increased your max speed by 2.5mph. And no you did not double the power consumpsion. You generally increase it by the same estimated 10%.
I do not disagree that a single motor is the best and simplest answer though. I personally think twin motors are more then the average person can deal with mechanically.
REdiculous
10 kW
Good point, I didn't consider that at all - I just assumed a fixed ratio for some reason.
theRealFury
10 kW
The ONLY benefit i can think of for running both these drive types is that you could rune more silent on the flats with the hub motor. Really if you go to the trouble of designing and installing a RC chain drive setup then you already have the best of both worlds though the rear gears :wink: :wink:
You want top speed, drop it into bottom gear.... you want max torque, move it all the way to the top. I think the reasons most people go with a hub is the simplicity of it and the ease of installation. Also hubs have fewer parts that can break / fatigue.
My main argument still holds though, if your already putting an RC drive on your bike then you wont need a hub aswell
You want top speed, drop it into bottom gear.... you want max torque, move it all the way to the top. I think the reasons most people go with a hub is the simplicity of it and the ease of installation. Also hubs have fewer parts that can break / fatigue.
My main argument still holds though, if your already putting an RC drive on your bike then you wont need a hub aswell
AussieJester
1 TW
theRealFury said:The ONLY benefit i can think of for running both these drive types is that you could rune more silent on the flats with the hub motor. Really if you go to the trouble of designing and installing a RC chain drive setup then you already have the best of both worlds though the rear gears :wink: :wink:
You want top speed, drop it into bottom gear.... you want max torque, move it all the way to the top. I think the reasons most people go with a hub is the simplicity of it and the ease of installation. Also hubs have fewer parts that can break / fatigue.
My main argument still holds though, if your already putting an RC drive on your bike then you wont need a hub aswell
Well said
... There's zero benefit of running two wheel drive bicycles period, if therewas advantages to having two wheel drive, mass produced motorbike would be 2 wheel drive, some manufactures have
dabbled with it, none for on road use exist t anymore to my knowledge, Seen several manufactures Moto-X bikes, which
have next to no use for front wheel drive anywayz :-S the front wheel skims the ground at best
when it is firmly on the ground, its under braking. I could just imagine
the crashes if two wheel drive bikes did exist in great numbers, people getting on the gas too soon out
of a corner and BAM! there goes your front wheel, face meet road kind-a stuff, simply too dangerous IMHO
you need good feel through the front wheel of a bike, a heavy barely round, vibrating hub motor spinning up willy nilly in a corner
would be one of the nastiest things i could think of on a bike that was ridden at any sort of spee on the road.
Then there's all the weight and extra crap you need to put a two wheel drive bike together, will
weigh you down even more and cancel out any minimal speed gains you might have had, might as well up battery
voltage or use a bigger chain drive motor if you want more speed...
KiM
John in CR
100 TW
AFG,
I'm working on something similar, but with 2 motors I see no need for changeable gearing on either. A hub motor gets pretty close all on its own, so my interest is adding a second small motor that is geared quite low to help out with the low speed acceleration of hard take-offs and to maintain a decent minimum speed up hills where the grade is too steep for the hubbie.
John
I'm working on something similar, but with 2 motors I see no need for changeable gearing on either. A hub motor gets pretty close all on its own, so my interest is adding a second small motor that is geared quite low to help out with the low speed acceleration of hard take-offs and to maintain a decent minimum speed up hills where the grade is too steep for the hubbie.
John
I have several times considered a freewheeling geared hub motor on the front of one of my cargo bikes while having the rear chain-driven from pedals + motor. But in my case, the hub in front would only be there for "emergencies", for when/if something bad happens to the chain drive that I can't fix on the road, so I can still get home. (because that has happened a few times on CrazyBike2 when I had a powerchair motor running into the chain drive, and it was no fun getting home, or in a couple of cases, to work).
In theory I'd also be able to get more overal power out of the system (depending on gearing/etc) with both motors at once, but I shouldn't ever need that if I gear the chain drive correctly.
I also have this planned for similar reasons on a delta trike, with the freewheeling geared hub in the right rear wheel (which isn't driven by the chain in the trike kit frame I have), and the left rear wheel being driven by pedals + motor via chain. Front wheel will just be a wheel.
In theory I'd also be able to get more overal power out of the system (depending on gearing/etc) with both motors at once, but I shouldn't ever need that if I gear the chain drive correctly.
I also have this planned for similar reasons on a delta trike, with the freewheeling geared hub in the right rear wheel (which isn't driven by the chain in the trike kit frame I have), and the left rear wheel being driven by pedals + motor via chain. Front wheel will just be a wheel.
