Resistance of e-bikekit.com direct drive hub motor

[DesignerDan]

Hello,
I've been wanting and researching ebikes for quite a while now and I finally have the money for one. I'm most interested in the kits from e-bikekit.com. I was wondering how much resistance the direct drive hub motor has when there is no power being sent to it. I've searched this forum for it and I've found conflicting answers. I've read that someone people say the resistance is too much for them to enjoy riding their bike without using the battery and I've also read that the resistance isn't too noticeable.
I ride my bike a lot. So I don't want a lot of resistance from the motor when I'm not using the battery. A geared hub motor has no resistance because it has the free wheel but the one from e-bikekit is really small and only rated for 350-500 watts. I was looking for something in the 20-30 mph range on 48v. If I get a direct drive kit will it be really annoying to ride the bike without of the battery?

Here's a little info: I have a 1000 dollar budget. I live in south west Florida so I don't have to worry about hills. I'm looking for 20-30 mph on 48 volts. Something with decent range. I could care less about noise. I only weigh 140. Having good acceleration would be nice. But most importantly, the bike needs to be efficient to pedal and ride when I'm not using the battery.

 

[wineboyrider]

I have both the direct drive wheel and the geared motor wheel and you will be more pleased with the geared kit if you pedal a lot. I like the DD motor, because I don't...The resistance is less on the DD kit when you don't have regen engaged, perhaps this is why there are conflicting reports. BOL.

 

[DesignerDan]

Thanks for the reply. The only problem is the geared motor is only said to go 17.5 mph on 36v. And they don't recommend using it on 48 volts :/

 

[Ykick]

Weight of all the components will be more noticeable than actual motor drag IMO. My DD's pick up plenty of speed when coasting down even mild hills. As WB noted, the regen thing may be confusing things in that regard.

But you'll have weight with any type of motor, controller and battery system. The trick is to ride like a pedal bike and add just enough throttle to make up for the weight/drag. Ridden this way 10 mile full throttle battery may easily last 30 miles or more.

 

[DAND214]

The geared hub does just over 21 on 48v. No real drag while coasting or oedaling.
The 9c dd has a fair amount of drag but it can be pedaled.

The Mac kit from Cell_man is your speed wanted and is in your price range. Even on 36v it's plenty fast.

My favorite hub is Cute 128 gear hub but it is too fragile 3 down with gears blown and can't get gears, even from the manufacturer ANANDA! Great motor just shitty service!!

Dan

 

[nuevomexicano]

Thanks for the reply. The only problem is the geared motor is only said to go 17.5 mph on 36v. And they don't recommend using it on 48 volts :/

I've been running a 350-500W geared hub motor from Amped Bikes (similar motor to the e-bike kit you're considering) on 48V for about 500 miles since late Spring. It runs easily in the mid 20's with a top speed on flats just over 27mph. I have a fairly step climb, more than 800 feet in less than a mile, on my 6 miles each way daily commute. The motor does get warm, but not at all hot to the touch. Its running great so far. I love the small motor size and the freewheel. The bike is heavy enough with the motor that I don't take it to ride specifically without the motor (I have other bikes for that), but I do pedal a fair amount on the flats without turning on the motor.

 

[DesignerDan]

Thanks everyone. hhhmmmm I'm thinking maybe I will keep my bike for regular biking and maybe convert a different bike to the direct drive hub motor and have that for when just want to get from place to place without doing too much work pedaling.

 

[yopappamon]

You can always set the cruise control at a slower speed and pedal above that. Kind of a pedal assist from the motor.

 

[DesignerDan]

yea but then if I drain the battery doing that and I'm not done riding my bike, I will have to pedal harder because of the drag of the direct drive motor.

 

[dogman dan]

Now you are on the right track. Don't ruin your favorite pedaler with battery and motor weight. Then take a lead sled of a steel frame mtb and motorize that. Just run the motor all the time on the motor bike. You CAN run very low power levels and get a nice assist with both gearmotors and dd motors if you need to stretch range. At 15-18 mph, battery range really stretches. But most likely, like most of us, you will really enjoy flying along at 25-30 mph, still pedaling, but mostly just enjoying the motor. Especially on the shorter trips.

The Mac motor from cellman is much more powerful, though heavier, than the other small gearmotors. The speed winding version is quite fast at 48v. But it will take a bit more battery, to go fast for very far. A slow and small gearmotor is still a nice bike. But most of us here go for power and speed.

 

[Dave Sloan]

The 9C when you first buy it has a fair amount of resistance when new because the bearings are tight. After 500 km or so it will lossen up enough that you can ride it with very little resistance. You would be better off getting a front hub because it is easier to switch out a front wheel if you do not need the weight factor. To remove the controller with the wheel - just velcro it under the handle bars - that way the unit can be easily unplugged. I use a GM controller because of the ease of removal/replacement. When I walk the dog I just pedal the bike without a battery.

 

[adrian_sm]

Funny this is the same debate I had myself, after having ridden a DD hub for a long time as a commuting bike to and from work, 5 days a week. A MTB with a Cystalyte 408 DD hub, which weighs ~30kg with a 48V10Ah battery.

Actually I think the turning point was when I made a big detour on the home one day and ran out of battery. The bike was now so heavy, and had so much drag compared to a normal bike, I thought there must be a better solution. I had even hooked up my bike lights to a DC-DC convertor which was great when I had the main pack charged, but now I was riding with a heavy bike, up hills, in traffic with no bike lights unless I pedalled fast enough to use my DD hub BEMF to power the DC-DC up.

Anyway, I ended up designing and building the lightest weight ebike I could. With the aim of making it as easy to pedal unpowered, while still having the power of an ebike when needed. This resulted in a friction drive setup on a road bike. Weighing in at ~13kg, no additional drag when unpowered, and 1-2000w of power on tap when needed, and a good 30km+ range when powered. And most importantly it still feels like a normal bike.

- Adrian

 

[DesignerDan]

That's a nice looking bike! I've considered making a friction drive because it seems like it would be simple to make. I'm good with tools but I do not have access to a CNC machine so the design and parts would have to be really simple to make. I also am into the r/c hobby so I have a castle creations 160 hv and a 2000watt r/c motor just sitting around.

And dog man, this might be a stupid question but where can I find this "Mac motor"?

 

[adrian_sm]

If you are handy and have some spare time, make one. I did all my prototypes with just a drill press, a hand saw, and a tap set to thread holes.

The most difficult bit was getting the geometry sorted, then resolving a throttle for road bars, and finally limiting power and smoothing the drive engagement so anyone can use it without instructions. I you do decide to make one, let me know and I'll help where I can, but enough off topic stuff on friction drives.

The MAC motors are I believe these ones: http://www.emissions-free.com/catalog/c5_p1.html

Good motor from all accounts, just don't put too much power through them, and don't jump them too much. But if you keep to ~1000w and ride on the road most of the time you'll be fine.

- Adrian

 

[ZOMGVTEK]

If you pedal and can accept a lower power motor thats likely to be less reliable, geared is the way to go.

DD's can take a ton more power, since they don't have gears to break. All you need to do is keep them cool, and you can run a 4-6KW into a 1KW hub, no problem. You are going to notice a DD when you pedal, whereas the geared motors have a freewheel, so you're not even spinning the heavy motor when you pedal. Since I dont pedal, I prefer DD's. My bike is very heavy, but it picks up speed fast down hills, and has a whole lot of mass to keep it going. The bike coasts farther than most pedal bikes, which is nice. However, pedaling is BRUTAL on it. It feels like all your power is going into a brick wall.

 

[sk8norcal]

so what is the physics behind this ? (sorry, electronics noob)

can someone explain this? or links?

does size of the motor or strength of the magnet affect the resistance?

there is even more resistance when pushing the bike backward, right?

resistance difference in brush vs brushless?

my bosch dc brush motor on my belt drive scooter have tons of resistance, even worse pushing backward.
but my bladeZ dc brush motor have much less...

 

[DesignerDan]

Ok well it sounds like it will be a bad idea to but a direct drive hub motor on my bike that I like to use just to pedal. So I guess I will but the direct drive on a different bike and just hope I don't run into a situation where the batteries run out.

 

[adrian_sm]

Yep. If you don't run out of batteries, and use the motor most of the time, the DD hub are great.

But if you want you bike to still feel like a normal bike when not using the motor, your right it is a bad choice.

 

[dogman dan]

Good plan I think. If you know you need to stretch range for a particular trip, slow down to 15-18 mph and your range will nearly double. Get a decent size battery to begin with, such as 48v 15 ah or 36v 20 ah, and you will have easy 20-25 mile range. That eliminates range issues for many trips. Pedaling slow, 40 miles is possible.

If you are screwed and you know it in time, you can ride with the throttle just barely tickling and use about 50w. That eliminates the magnet cogging while you pedal home on the last bit of battery. The old ebikekit controllers also had a 200w jumper wire. Connecting that jumper slowed the bike way down, so you could use a weak battery or extend range, or be legal in europe.

With some experience, it's quite possible to use very low wattage with a dd motor on a heavy bike, yet still get a lot of the feeling of riding a lighter bike. It will handle heavy, but pedal like it's light. That's the beauty of an ebike.

In the meantime, you can start designing and building your friction drive for the roadbike.

 

[adrian_sm]

Just for reference I took my friciton drive road bike for a spin the other day, which might be of interest too you since we are talking range, economy, drag etc.

Here are the setup and stats:
Battery: LiPo 5s20Ah
Power Limit: 500w

Dist: 41km
Cruising Speed on the flat: ~40kph
Max Speed: 59.9kph
Battery used: 301wh
Average Speed: 27kph
Trip economy: 7.3 wh/km

I did slow down and pedal through a huge park in the middle of the trip, which had a bunch of shared gravel bike paths, otherwise it would have been a bit quicker.


- Adrian