Direct drive vs. geared hub motor?

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Direct drive vs. geared hub motor?

Postby klmadison » Mon May 17, 2010 10:02 am

I am a newbie planning to buy my first e-bike, likely from Amped, and would appreciate advice on choosing a direct drive or geared hub motor. I am looking at a front hub motor. Primary use will be commuting to work, 13 miles each way with a few moderate hills. My plan is to pedal most of the time along with use of the motor.

I like the lower weight, freewheeling ability, and greater efficiency of the geared motor, but then I like the greater simplicity and lower cost of the direct drive. Amped gives a top speed of 20 mph for the geared motor and 23 mph for direct drive and I don't have a clear idea of what will happen with either one if while pedaling along with a tailwind I want to exceed that speed with either one. What about long term durability or maintenance issues? Any significant differences in the experience of using either type?

I'd be grateful for any suggestions anyone might have.

Ken
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Re: Direct drive vs. geared hub motor?

Postby yopappamon » Mon May 17, 2010 10:34 am

Hi Ken,

I have the amped rear geared kit. I've been using it for about 250 miles and commute most everyday ( not today, it's RAINING in southern California! ). I have no real complaints about the kit and like it very much. I haven't used a direct drive unit yet, so I don't have much to compare it to.

To answer one of your questions, if you are going down hill and pedal faster, you will go faster than the 20mph, the motor will assist for a bit, maybe up to 22-23 then it will just drop out and it's all you and the hill. The motor will not drag you back to 20. I think my max speed down hill is around 27.

If I were to nit pick and find anything that could have been done better here they are:

-The rim is quite deep and when mounting the tire, the schrader valve doesn't want to stick out far enough to let you fill the tire. I had to struggle a bit with some pliers to hold it out and get a hold of it with the pump. I think this might be an issue with all hd rims, though. And it might be that the tube I got had a short stem.
-There is no on/off switch/button and you get a nice arc when you connect the batteries. The button on the throttle is for cruise control. I will take cruise control and the arc any day. Cruise is AWESOME!

I thought 20 mph would be plenty and seem very fast. I have to say, I want more speed now. So I have an e-bikekit direct drive on the way.

13 miles each way. Are you planning on recharging at work? I get around 2.5 miles per battery amp hour. I have 20ah, 36v thundersky LiFePo4 batteries, and I can get about 30 miles on half the pack.

Also, make sure you have steel front forks if you are going to use a front kit. And order the amped torque arm at the same time you order the kit.
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Re: Direct drive vs. geared hub motor?

Postby Drunkskunk » Mon May 17, 2010 11:36 am

If you like Ampbike, you should also checkout Ebikekits.com who sell Nine Continent hub motors.

Geared is lighter, and more efficent at low speeds and accelerating. Its also louder.
Direct drive hubs are heavier, but quieter, and more efficent at cruising speed.

A motor's top speed is what it does under load. If you lift the wheel off the ground, it will run faster.
If the speed while riding is 20mph, and the unloaded speed is 30mph, then any speed you peddal above 20 will still have assistance from the motor, in diminishing amounts up to 30mph. After 30, the free wheel will release on a geared motor and the motor will spin free. On the direct drive hub, it will do nothing diffrent untill you get going much faster, at which point, there can be some resistance felt increasing if you have the throttle open.

There are a few advantages of the non-geared hubs for comuting. Simplicity is one. there is simply less to fail. No gears to strip. no freewheels to fail, fewer overheating issues. And if you have need of being able to arive every day on time, then the simple system may be better.
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Re: Direct drive vs. geared hub motor?

Postby John in CR » Mon May 17, 2010 1:07 pm

I'm not going to comment on durability, because hopefully the latest breed of geared hubs has better quality gears and freewheel clutches. The biggest difference for which there's no getting around is that you can readily get increased performance with direct drive hubs, and get you higher power where geared hubs are certain to fail. With geared hubs, you really need to stick near the manufacturer's recommendations for voltage and current.

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Re: Direct drive vs. geared hub motor?

Postby MitchJi » Mon May 17, 2010 1:16 pm

Hi,

Some info here:
http://www.ebikes.ca/hubmotors.shtml
Summary of Hub Motors…
Best Wishes!

Mitch


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Re: Direct drive vs. geared hub motor?

Postby dogman dan » Mon May 17, 2010 4:16 pm

Both kinds have thier riders. The guy who wants assist, and might pedal significant distances with the motor off wants the freewheel of a gearmotor.

The guy who just pegs the throttle on the stop, and rides 27 mph all day on a 48v battery wants the direct drive. Thats 1200 watts on an ebikekit, so that'll get you up a pretty steep hill with no need for gears.

As for efficiency, when ridden at the same speed, I see very very very similar wattages.

No comment on the vendors, other than the one closer to you makes some sense. Both have good product out there.
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Re: Direct drive vs. geared hub motor?

Postby klmadison » Tue May 18, 2010 1:29 am

Thanks to all of you for your good information and suggestions. I am inclining now toward the direct drive motor.
Ken
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Re: Direct drive vs. geared hub motor?

Postby Mark_A_W » Tue May 18, 2010 5:54 am

Unless you get an X5, or overvolt/overamp the hell out of the big 9C, a big geared motor will eat a DD motor alive.


My MAC Shanghai, at 64v 30A, is faster, and pulls harder than a 408 at 64v 30A, and I would weigh 20kg more than the 408 rider.


And the difference between the MAC and my old, smaller 9C is HUGE, for the same size and weight.


It's come close to death, but with composite gears, the MAC is holding up.


If you want total reliability, go DD. If you want performance without weight, go geared.
Under construction: Giant DH Team, MAC Shanghai, Infineon 18 FET controller, 64v Headway battery. LINK!!

Retired: Kona Dawg Dually + Bomber Triple Clamp forks with Nine Continents front hub motor, 48v 10Ah Headway LiFePO4 Pack + 12v 10Ah Headway LiFePO4 booster pack (nominal 64v).

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Re: Direct drive vs. geared hub motor?

Postby dogman dan » Tue May 18, 2010 6:27 am

At the same wattage, a gearmotor sould outperform a dd. Most gearmotor kits though, are lower wattages. The amped kit may be an exception. If it has a 20 amp controller, then it should put out the same watts as a dd kit with similar controller. But at 48v the 9c package perfrorms pretty good, climbing up to 10% grades pretty good with a bit of pedaling. 7% is no problem with no pedaling.

I have found though, that a big dd like a 9c has an easier time shedding the heat than a gearmotor. So depending on use and climate, that could matter.
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Re: Direct drive vs. geared hub motor?

Postby Mark_A_W » Tue May 18, 2010 6:44 am

dogman wrote:At the same wattage, a gearmotor sould outperform a dd. Most gearmotor kits though, are lower wattages. The amped kit may be an exception. If it has a 20 amp controller, then it should put out the same watts as a dd kit with similar controller. But at 48v the 9c package perfrorms pretty good, climbing up to 10% grades pretty good with a bit of pedaling. 7% is no problem with no pedaling.

I have found though, that a big dd like a 9c has an easier time shedding the heat than a gearmotor. So depending on use and climate, that could matter.



However, IMO a geared motor is less efficient.

The increase in low speed efficiency is nowhere near offset by the increase in drag at cruising speed (which could be due to the high Kv of my particular geared motor, or it could be mechanical losses due to the gears).
Under construction: Giant DH Team, MAC Shanghai, Infineon 18 FET controller, 64v Headway battery. LINK!!

Retired: Kona Dawg Dually + Bomber Triple Clamp forks with Nine Continents front hub motor, 48v 10Ah Headway LiFePO4 Pack + 12v 10Ah Headway LiFePO4 booster pack (nominal 64v).

Powered by the sun :)

Dead: Jamis Dakar frame, Mongoose Pro Downhill frame, cooked Lipo booster pack....and various other bits and pieces...
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Re: Direct drive vs. geared hub motor?

Postby dogman dan » Tue May 18, 2010 7:06 am

I've found no differences in efficiency worth worrying about, either at fast or slow speeds with the ones I've had. Sure there are measurable differences, but not enough to make me choose one or the other.

The ideal place to choose a gearmotor might be when there are lots of shallow grade hills along the way, making the freewheel real nice for turning off the motor on the slight downhills.

But in general, if you want more speed, it's easier to go dd, since you don't have to worry as much about breaking stuff inside overvolting the hell out of it.
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Re: Direct drive vs. geared hub motor?

Postby docnjoj » Tue May 18, 2010 7:16 am

I chose geared motors for a slightly different reason. They are light! I really like to keep my suspension set for large movement and the unsprung weight of a heavy DD really is noticible on some of our rougher roads. The geared hubs (Bafang in my case) weigh not much more that the original wheel and gears, thus preserving the ride. I'm an old guy with a bad back and having that subtle cushion of soft springs and good shocks really helps. Stick 20 lbs of unsprung weight on the rear and the ride and some handling really is much poorer in my view.
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Re: Direct drive vs. geared hub motor?

Postby dogman dan » Tue May 18, 2010 2:44 pm

Absolutely right about that. Switching from a 5304 to a 9c 6x10 on my dirt bike is a big improvement. Both motors are rear hubs. You can still feel a lot of weight back there, but it's not nearly so hard to adjust to as the 5304 was. I've been wanting to try a bmc 600 watt rear but the 6x10 is making a nice bike for trials type riding at 10 mph. Can't climb a wall, but I don't have to help it up hills till they get really steep.

But the 6x10 is a pretty slow motor, compared to others. Not too much slower than some gearmotors though.
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Re: Direct drive vs. geared hub motor?

Postby The Stig » Tue May 18, 2010 3:40 pm

Mark_A_W wrote:
dogman wrote:At the same wattage, a gearmotor sould outperform a dd. Most gearmotor kits though, are lower wattages. The amped kit may be an exception. If it has a 20 amp controller, then it should put out the same watts as a dd kit with similar controller. But at 48v the 9c package perfrorms pretty good, climbing up to 10% grades pretty good with a bit of pedaling. 7% is no problem with no pedaling.

I have found though, that a big dd like a 9c has an easier time shedding the heat than a gearmotor. So depending on use and climate, that could matter.



However, IMO a geared motor is less efficient.

The increase in low speed efficiency is nowhere near offset by the increase in drag at cruising speed (which could be due to the high Kv of my particular geared motor, or it could be mechanical losses due to the gears).


I would say the freewheeling of a gear motor alows you to get better range than a DD. Especially if you plan to pedal most of the way as the OP is going to. Pedaling + gearmoter will allow you to not use throttle a lot of the time. A DD will have drag when only pedaling because it has no freewheel. If you live in a slightly hilly area you can take full advantage of the freewheeling by not using throttle when going down hill.
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Re: Direct drive vs. geared hub motor?

Postby Mark_A_W » Tue May 18, 2010 4:46 pm

The Stig wrote:
Mark_A_W wrote:
I would say the freewheeling of a gear motor alows you to get better range than a DD. Especially if you plan to pedal most of the way as the OP is going to. Pedaling + gearmoter will allow you to not use throttle a lot of the time. A DD will have drag when only pedaling because it has no freewheel. If you live in a slightly hilly area you can take full advantage of the freewheeling by not using throttle when going down hill.



In my experience the opposite is true.


I had 40km range with my DD 9C (154mm size), cruising at 40-45kmh.

If I'm lucky I can eek out 28 km from the MAC, at 70% throttle (limited), cruising at 40-45kmh.


Same battery.


It may not be the gears that is the difference. But something sure is different.

Oh, and I can go 50-55kmh on the MAC if I want. But then I'm lucky to get 20km range.
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Re: Direct drive vs. geared hub motor?

Postby mr.electric » Tue May 18, 2010 6:04 pm

I have an ebikekit direct drive motor and a BMC geared 1000 watt motor both at 48v. The BMC has about 3 times the power and similar weight as the Ebikekit. The BMC also cost about three times as much as the ebike kit!
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Re: Direct drive vs. geared hub motor?

Postby dogman dan » Tue May 18, 2010 7:41 pm

I'm not familiar with the MAC motor. Now I'm curious, it sounds like a pretty big powerfull motor. My comparisons have been to less powerfull gearmotors, so you end up at partial throttle on the dd motor to compare.

My comparisons didn't include any BMC motors, nobody sending me those free. But I did compare Aotema, 9c 9x7, and a Fusin gearmotor. I have also owned heinzmanns, but they are very different, being a brushed motor. But all three of those motors ridden the same 15 mile route on the same battery used nearly exactly the same watthours if ridden at exactly the same speed. The dd was slightly more efficient, since no pedaling without the motor was involved in the test.

The beauty of a gearmotor though, is that you can pedal along with no motor resistance at all. But I rarely do.
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Re: Direct drive vs. geared hub motor?

Postby Mark_A_W » Tue May 18, 2010 9:45 pm

The MAC Shanghai "Puma" is basically the same motor as the BMC.
Under construction: Giant DH Team, MAC Shanghai, Infineon 18 FET controller, 64v Headway battery. LINK!!

Retired: Kona Dawg Dually + Bomber Triple Clamp forks with Nine Continents front hub motor, 48v 10Ah Headway LiFePO4 Pack + 12v 10Ah Headway LiFePO4 booster pack (nominal 64v).

Powered by the sun :)

Dead: Jamis Dakar frame, Mongoose Pro Downhill frame, cooked Lipo booster pack....and various other bits and pieces...
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