Would a 1500w Direct Drive Hub Get Me Up Short but Steep Hills on Full Suspension Bike without frying?

General Discussion about electric bicycles.
donn   10 kW

10 kW
Posts: 683
Joined: Aug 13 2018 10:30am
Location: Seattle

Re: Would a 1500w Direct Drive Hub Get Me Up Short but Steep Hills on Full Suspension Bike without frying?

Post by donn » Feb 28 2019 10:37pm

20% is pretty intense. You will start to feel like you're going to tip over backwards, and traction will be a big issue on unimproved surfaces. I get rough grade values with Google maps - select the section of road with beginning and end markers and get bicycle "directions" in km. Distance and elevation will appear in meters, divide and multiply by 100. Works only for roads though, roads that are mapped in their data.

User avatar
itsallwhite   100 mW

100 mW
Posts: 36
Joined: Feb 07 2019 5:02am

Re: Would a 1500w Direct Drive Hub Get Me Up Short but Steep Hills on Full Suspension Bike without frying?

Post by itsallwhite » Mar 01 2019 12:13am

donn wrote:
Feb 28 2019 10:37pm
20% is pretty intense. You will start to feel like you're going to tip over backwards, and traction will be a big issue on unimproved surfaces. I get rough grade values with Google maps - select the section of road with beginning and end markers and get bicycle "directions" in km. Distance and elevation will appear in meters, divide and multiply by 100. Works only for roads though, roads that are mapped in their data.
These 'roads' won't be on Google maps, but I might be able to find similar ones and map those to get a comparison. Also have a couple of biker friends who might have a better idea.

All except very short 20 metre hill I think is less than 20%, maybe 15% at a guess, but thought I'd put 20% in simulator to see worst case scenario!
Bike 1: Giant Hybrid Steel Frame (old) with TSDZ2 48v 500w.
Bike 2: GT Sensor 2 full suspension mountain bike. Work in Progress - ready to 'electrify'!
House: 100% off grid - 5.6kw solar array with selectronics inverter and 24 Volt 1450 Ah BAE Gel battery Bank

User avatar
E-HP   1 MW

1 MW
Posts: 1948
Joined: Nov 01 2018 9:20pm

Re: Would a 1500w Direct Drive Hub Get Me Up Short but Steep Hills on Full Suspension Bike without frying?

Post by E-HP » Mar 01 2019 12:20am

itsallwhite wrote:
Feb 28 2019 9:45pm
Thank you for your help. Looking at the simulator with a 9C 2707 with a 20amp controller and 48v battery (which would give 960w). Total load of 352lb, with a 100w human power and 20% grade. Overload time 6 minutes.

If I could maintain a speed of 10km+ the motor would overheat in 9.7 minutes with a 930w load and 41% efficiency. If speed dropped to 5km p/h efficency drops to 24% and overload time <5 minutes.

My hills are steep but very short and total journey is 5 minutes usually.
Doesn't seem like any of your steeper hills are long enough to cause an overheating issue. Add some Statorade for insurance and you probably won't need anything else, especially since you can almost do the same hills without a motor.

User avatar
itsallwhite   100 mW

100 mW
Posts: 36
Joined: Feb 07 2019 5:02am

Re: Would a 1500w Direct Drive Hub Get Me Up Short but Steep Hills on Full Suspension Bike without frying?

Post by itsallwhite » Mar 01 2019 4:51am

One thing I did notice from the simulator though is how much (or little) assistance I'll get from the motor on the hills...

If my speed drops to <10km p/h, the motor efficiency drops to only 25% or whatever, then I might only be getting 250w input from the motor, with the other 750w wasted as heat. I was hoping for a bit more support than that up the hills!

Is this how it works...when the efficiency drops so does the effective power available from the motor?

(I think the 48v battery I have will prob only give 20a continous so 1000w might be the max I can get)
Bike 1: Giant Hybrid Steel Frame (old) with TSDZ2 48v 500w.
Bike 2: GT Sensor 2 full suspension mountain bike. Work in Progress - ready to 'electrify'!
House: 100% off grid - 5.6kw solar array with selectronics inverter and 24 Volt 1450 Ah BAE Gel battery Bank

User avatar
dogman dan   100 GW

100 GW
Posts: 35849
Joined: May 17 2008 12:53pm
Location: Las Cruces New Mexico USA

Re: Would a 1500w Direct Drive Hub Get Me Up Short but Steep Hills on Full Suspension Bike without frying?

Post by dogman dan » Mar 01 2019 7:28am

What you want to do will work, with 2000w or more, using a large DD hub, in 26". This means a wide motor, like 35 mm wide stator. I'm not sure what your "1500w" motor idea is. But if the motor and wheel is over 15 pounds, its the bigger one. Run one of these on 48v, with 40 amps controller, and you will go up steep hills fast enough to keep the motor cool, up to about 450 pounds.

What will struggle is a 500w rated, 2807, 9 continent type motor typical in the " 48v 1000w kits" The limit for those is around 300 pounds.


However, two of these 1000w kits, one on the front wheel and one on the back will do er, its again 2000w. Or even a smaller geared motor on the front, and the dd in the back.


The chatch 22 here is that you can quickly kill a battery pulling 40 amps from it. So the big motor will NOT run for long on the battery you have. ( As you just said, so you know this) You need about 30 ah of typical round cell battery to run the big motors. That much battery can just be carried on the trailer.


If you do want to make a bike that will carry that load up the hills on 1000w, you need that 1000w kit in a 20" wheel. Then the bike will need some modification to run that small wheel in back. See the link below for bolt on longtail. Or you build a bike, like the mixte longtail link below.

donn   10 kW

10 kW
Posts: 683
Joined: Aug 13 2018 10:30am
Location: Seattle

Re: Would a 1500w Direct Drive Hub Get Me Up Short but Steep Hills on Full Suspension Bike without frying?

Post by donn » Mar 01 2019 10:48am

dogman dan wrote:
Mar 01 2019 7:28am
If you do want to make a bike that will carry that load up the hills on 1000w, you need that 1000w kit in a 20" wheel. Then the bike will need some modification to run that small wheel in back. See the link below for bolt on longtail. Or you build a bike, like the mixte longtail link below.
Or ... I'm not very clever about stepping out of the box, so don't take this too seriously, but if it's all about a trailer load of kids ... maybe the motor could be installed in the trailer, if it already has small wheels.

User avatar
E-HP   1 MW

1 MW
Posts: 1948
Joined: Nov 01 2018 9:20pm

Re: Would a 1500w Direct Drive Hub Get Me Up Short but Steep Hills on Full Suspension Bike without frying?

Post by E-HP » Mar 01 2019 12:22pm

itsallwhite wrote:
Mar 01 2019 12:13am
These 'roads' won't be on Google maps, but I might be able to find similar ones and map those to get a comparison. Also have a couple of biker friends who might have a better idea.

All except very short 20 metre hill I think is less than 20%, maybe 15% at a guess, but thought I'd put 20% in simulator to see worst case scenario!
The problem is, everyone's idea of steep is different, depending on what people are used to. I use this tool to determine elevations and distances. You don't need roads; if you put the maps in satellite mode you can use physical landmarks to find your trails/roads. The first tool allows you to determine elevation of any location and the second tool allows you to determine the distance between points, so between the two you can figure out the grades in your route.

Here is a trail behind my house (I'm at 137 feet above sea level); my starting point is down the hill (~sea level), and the trail head is a couple miles down the road and at around 150 ft. I use the elevation tool to determine the elevations of the points on the trail I want to measure:
https://www.freemaptools.com/elevation-finder.htm
elevation.jpg
Then I use the distance tool to determine the distance between the same points:
https://www.freemaptools.com/measure-distance.htm
distance.jpg
Then you can do the math for rise over run to determine the grade. For this example, the distance is 0.09 miles or 845 feet. The elevation change is 144 ft, so the grade is 17% for the section of trail in the example. I had to pedal hard, but the motor and controller were barely warm over this short distance, or anywhere else along the ride.
map.jpg
map.jpg (140.3 KiB) Viewed 1694 times
Obviously it's better to use longer distances in order to reduce errors from eyeballing to points on the map.

User avatar
itsallwhite   100 mW

100 mW
Posts: 36
Joined: Feb 07 2019 5:02am

Re: Would a 1500w Direct Drive Hub Get Me Up Short but Steep Hills on Full Suspension Bike without frying?

Post by itsallwhite » Mar 03 2019 6:36pm

donn wrote:
Mar 01 2019 10:48am
dogman dan wrote:
Mar 01 2019 7:28am
If you do want to make a bike that will carry that load up the hills on 1000w, you need that 1000w kit in a 20" wheel. Then the bike will need some modification to run that small wheel in back. See the link below for bolt on longtail. Or you build a bike, like the mixte longtail link below.
Or ... I'm not very clever about stepping out of the box, so don't take this too seriously, but if it's all about a trailer load of kids ... maybe the motor could be installed in the trailer, if it already has small wheels.
I like this idea, wonder if its been done before...?
Bike 1: Giant Hybrid Steel Frame (old) with TSDZ2 48v 500w.
Bike 2: GT Sensor 2 full suspension mountain bike. Work in Progress - ready to 'electrify'!
House: 100% off grid - 5.6kw solar array with selectronics inverter and 24 Volt 1450 Ah BAE Gel battery Bank

User avatar
amberwolf   100 GW

100 GW
Posts: 31731
Joined: Aug 17 2009 6:43am
Location: Phoenix, AZ, USA, Earth, Sol, Local Bubble, Orion Arm, Milky Way, Local Group
Contact:

Re: Would a 1500w Direct Drive Hub Get Me Up Short but Steep Hills on Full Suspension Bike without frying?

Post by amberwolf » Mar 04 2019 1:31am

"pusher trailer"; yes.

a few threads
search.php?keywords=pusher*+trailer*&te ... mit=Search
there's more not found in that list

billvon   1 GW

1 GW
Posts: 3051
Joined: Sep 16 2007 9:53pm
Location: san diego

Re: Would a 1500w Direct Drive Hub Get Me Up Short but Steep Hills on Full Suspension Bike without frying?

Post by billvon » Mar 04 2019 2:31pm

itsallwhite wrote:
Mar 03 2019 6:36pm
donn wrote:
Mar 01 2019 10:48am
Or ... I'm not very clever about stepping out of the box, so don't take this too seriously, but if it's all about a trailer load of kids ... maybe the motor could be installed in the trailer, if it already has small wheels.
I like this idea, wonder if its been done before...?
It has been done a lot. I've done it with good success. It's easiest if the trailer has "standard" bike wheels (i.e. mounts in dropouts) rather than on stub axles.
--bill von

EbikeAus   100 W

100 W
Posts: 287
Joined: Feb 04 2018 5:58am

Re: Would a 1500w Direct Drive Hub Get Me Up Short but Steep Hills on Full Suspension Bike without frying?

Post by EbikeAus » Mar 04 2019 6:11pm

I have the 48v (battery is 52v) 1000w rear hub kit and find it ok for hill climbing.. As long as you can get a decent run up.
Mine is throttle only, so I imagine with a bit of leg work it should be ok
Choose LiFe 8)

May all your batteries be fully charged and perfectly balanced :P

User avatar
itsallwhite   100 mW

100 mW
Posts: 36
Joined: Feb 07 2019 5:02am

Re: Would a 1500w Direct Drive Hub Get Me Up Short but Steep Hills on Full Suspension Bike without frying?

Post by itsallwhite » Mar 04 2019 6:49pm

EbikeAus wrote:
Mar 04 2019 6:11pm
I have the 48v (battery is 52v) 1000w rear hub kit and find it ok for hill climbing.. As long as you can get a decent run up.
Mine is throttle only, so I imagine with a bit of leg work it should be ok
Is it a regular ebay type kit or is it a slow wind / lower RPM kit for hill climbing?
Bike 1: Giant Hybrid Steel Frame (old) with TSDZ2 48v 500w.
Bike 2: GT Sensor 2 full suspension mountain bike. Work in Progress - ready to 'electrify'!
House: 100% off grid - 5.6kw solar array with selectronics inverter and 24 Volt 1450 Ah BAE Gel battery Bank

User avatar
itsallwhite   100 mW

100 mW
Posts: 36
Joined: Feb 07 2019 5:02am

Re: Would a 1500w Direct Drive Hub Get Me Up Short but Steep Hills on Full Suspension Bike without frying?

Post by itsallwhite » Mar 04 2019 7:21pm

E-HP wrote:
Mar 01 2019 12:22pm
itsallwhite wrote:
Mar 01 2019 12:13am
These 'roads' won't be on Google maps, but I might be able to find similar ones and map those to get a comparison. Also have a couple of biker friends who might have a better idea.

All except very short 20 metre hill I think is less than 20%, maybe 15% at a guess, but thought I'd put 20% in simulator to see worst case scenario!
The problem is, everyone's idea of steep is different, depending on what people are used to. I use this tool to determine elevations and distances. You don't need roads; if you put the maps in satellite mode you can use physical landmarks to find your trails/roads. The first tool allows you to determine elevation of any location and the second tool allows you to determine the distance between points, so between the two you can figure out the grades in your route.

Here is a trail behind my house (I'm at 137 feet above sea level); my starting point is down the hill (~sea level), and the trail head is a couple miles down the road and at around 150 ft. I use the elevation tool to determine the elevations of the points on the trail I want to measure:
https://www.freemaptools.com/elevation-finder.htm
elevation.jpg

Then I use the distance tool to determine the distance between the same points:
https://www.freemaptools.com/measure-distance.htm
distance.jpg

Then you can do the math for rise over run to determine the grade. For this example, the distance is 0.09 miles or 845 feet. The elevation change is 144 ft, so the grade is 17% for the section of trail in the example. I had to pedal hard, but the motor and controller were barely warm over this short distance, or anywhere else along the ride.

map.jpg

Obviously it's better to use longer distances in order to reduce errors from eyeballing to points on the map.
These tools are excellent thank you! I've just used them to calculate hill and the satellite map isn't that detailed in my area with such short distances it doesn't seem very accurate. The steepest climb is actually showing as a downhill using the tool. And the two other hills come out as 2 - 3%. When I look at a slightly longer distance (1km+) I can see it is working much better. Will play around a bit more.
Bike 1: Giant Hybrid Steel Frame (old) with TSDZ2 48v 500w.
Bike 2: GT Sensor 2 full suspension mountain bike. Work in Progress - ready to 'electrify'!
House: 100% off grid - 5.6kw solar array with selectronics inverter and 24 Volt 1450 Ah BAE Gel battery Bank

EbikeAus   100 W

100 W
Posts: 287
Joined: Feb 04 2018 5:58am

Re: Would a 1500w Direct Drive Hub Get Me Up Short but Steep Hills on Full Suspension Bike without frying?

Post by EbikeAus » Mar 05 2019 3:58am

itsallwhite wrote:
Mar 04 2019 6:49pm
EbikeAus wrote:
Mar 04 2019 6:11pm
I have the 48v (battery is 52v) 1000w rear hub kit and find it ok for hill climbing.. As long as you can get a decent run up.
Mine is throttle only, so I imagine with a bit of leg work it should be ok
Is it a regular ebay type kit or is it a slow wind / lower RPM kit for hill climbing?
Just the regular eBay one.
Has voilamart printed on it. I love it, best $250 I ever spent. I have around 500km on it now
Choose LiFe 8)

May all your batteries be fully charged and perfectly balanced :P

User avatar
itsallwhite   100 mW

100 mW
Posts: 36
Joined: Feb 07 2019 5:02am

Re: Would a 1500w Direct Drive Hub Get Me Up Short but Steep Hills on Full Suspension Bike without frying?

Post by itsallwhite » Mar 05 2019 4:11am

EbikeAus wrote:
Mar 05 2019 3:58am
itsallwhite wrote:
Mar 04 2019 6:49pm
EbikeAus wrote:
Mar 04 2019 6:11pm
I have the 48v (battery is 52v) 1000w rear hub kit and find it ok for hill climbing.. As long as you can get a decent run up.
Mine is throttle only, so I imagine with a bit of leg work it should be ok
Is it a regular ebay type kit or is it a slow wind / lower RPM kit for hill climbing?
Just the regular eBay one.
Has voilamart printed on it. I love it, best $250 I ever spent. I have around 500km on it now
Great to hear, what kind of hills have you got up with it? Anything off road / steep? Does it lose speed and bog down if you don't have a run up?
Bike 1: Giant Hybrid Steel Frame (old) with TSDZ2 48v 500w.
Bike 2: GT Sensor 2 full suspension mountain bike. Work in Progress - ready to 'electrify'!
House: 100% off grid - 5.6kw solar array with selectronics inverter and 24 Volt 1450 Ah BAE Gel battery Bank

miro13car   1 MW

1 MW
Posts: 1824
Joined: Mar 26 2007 1:30pm
Location: Calgary, Canada

Re: Would a 1500w Direct Drive Hub Get Me Up Short but Steep Hills on Full Suspension Bike without frying?

Post by miro13car » Mar 06 2019 1:40pm

By all means have some sort of thermal protection built into motor.
ebike drives DD motors with no temp. sensors and electronics sending signal to controller are useless, disaster waiting to happen.
Riding in constant fear that on any hill this cheap edrive would burn out takes all the pleasure away from you .
No way that you can ignore that
Eplus, Bionx

User avatar
itsallwhite   100 mW

100 mW
Posts: 36
Joined: Feb 07 2019 5:02am

Re: Would a 1500w Direct Drive Hub Get Me Up Short but Steep Hills on Full Suspension Bike without frying?

Post by itsallwhite » Mar 08 2019 12:01am

I found an ebay kit which claims to be a geared 1000w 48v motor (28a controller) - what do you think?

https://www.ebay.com.au/itm/26-1000W-48 ... SwRwxcfyh5

I am dubious if it is really geared but one of the images shows cogs so maybe?

Would this do a better job up the hills than non-geared option?
Bike 1: Giant Hybrid Steel Frame (old) with TSDZ2 48v 500w.
Bike 2: GT Sensor 2 full suspension mountain bike. Work in Progress - ready to 'electrify'!
House: 100% off grid - 5.6kw solar array with selectronics inverter and 24 Volt 1450 Ah BAE Gel battery Bank

User avatar
amberwolf   100 GW

100 GW
Posts: 31731
Joined: Aug 17 2009 6:43am
Location: Phoenix, AZ, USA, Earth, Sol, Local Bubble, Orion Arm, Milky Way, Local Group
Contact:

Re: Would a 1500w Direct Drive Hub Get Me Up Short but Steep Hills on Full Suspension Bike without frying?

Post by amberwolf » Mar 08 2019 12:48am

If you look at the "cogs" you will see that some extend out beyond the motor casing, so it is just someone photoshopping marketing crap in there. It's probably the inside of a clock or something.

The mtor casing shape, and size relative to the wheel, is about the same as any of the generic 500-1000w DD hubs.

It calls it a brushless gearless down in the details section; don't know where you see that it is a geared hub.

Personally, I wouldnt' buy from any seller I couldn't trust, and I certainly wouldn't trust any seller that makes confusing ad images like those. I'd probably report the ad to ebay as deceptive if it actually calls it a geared hub (I didn't see that, myself).


EDIT: Looks lke you've already been doing this...so ignore the below:
As far as what will do better up hills, go to http://ebikes.ca/simulator and compare similar DD and geared hubs under the conditions you will be using them under. Since it's unlikely most of the generic hubs out there will be in the simulator, you can only make a best guesstimate like that.



However, without physically testing each one in comparison to the others, none of us can say if one will be better than another, either. ;)



Somethign to keep in mind about geared hubs is taht they will overheat faster than a DD, all conditions the same, simply because the geared hub has more layers for the heat to have to pass thru, so it takes much longer for it to shed that heat. There are numerous threads on modifying motors for better cooling, including a "definitive testing" thread where methods were tested under controlled conditions to really compare them, so that's the best thread to start with.

But, the geared hub, if it can be kept at a sufficient RPM, may produce less waste heat than the DD hub under the same conditons; it depends on wheelsize and winding of the motor; as you can see in the simulator a faster winding will be less efficient at a lower speed under all the same conditions, without enough BEMF to counter the current thru it from the controller, the current flow heats the motor up. Slowing down more increases this problem, if the current into the motor does't change.

Setting up a system that will keep you at the best speed the motor can do even on the hill will help the motor stay cooler. Mulitple motors can run even better under such conditions, beause the load is split up between them. (but it increases the total mass being pushed up the hill)

User avatar
dogman dan   100 GW

100 GW
Posts: 35849
Joined: May 17 2008 12:53pm
Location: Las Cruces New Mexico USA

Re: Would a 1500w Direct Drive Hub Get Me Up Short but Steep Hills on Full Suspension Bike without frying?

Post by dogman dan » Mar 08 2019 7:30am

Re that link to the kit. That is your typical direct drive "1000w" 48v kit. Its not the fast 6t wind, (30mph) but the 7t wind that tops out at 278=-28 mpg.


This is what that motor can do. It can carry 300 pounds up long, and even steep hills. Like 8-10%. That 300 pounds is you, the bike, the motor, the battery, the trailer and the kids. I tested this motor to destruction for E-bikekit.com, and later became an employee there. Same type motor, and winding, but there are a zillion manufacturers of that same motor. At 300 pound load, it will climb 8% without slowing enough to cook the motor very fast. The way you know you are killing the motor, is if full throttle and your pedaling slows you below 12 mph. at 8-10 mph, you are on the way to melt down if your hill is too long. At 300 pounds, you can climb 6-8% grades at 13-15 mph. You can climb 8% for miles. for an hour or more. So I'm talking you can climb 2000 feet of vertical at 300 pounds. The motor will be hot at the top, but very unlikely you will melt one. Its quite hard to kill these motors with 48v, unless you overload them more.

I betcha your load is more like 400 pounds though, or even 450. This means your time to overheat shortens, very short if you slow to 8 mph with full throttle on it. So if you overload this motor, in 26" wheel, you will have about 30 min to get to the top of that hill.


I think you said the big hill is 2 miles? and only 200 feet? That is not steep, and a 1000w motor should do it. if you did slow to 8 mph, you'd be up it in 15 min. That will heat it up, but not melt it. Chances are, a hill that long that is only 200 feet gain, you will get up it in less than 15 min, and you will get up it at 12 mph or more.

Making the push trailer so you can use 20" wheel is a good idea, but more child trailers don't have the wheels in forks, and cannot use a hub motor easily.

But if that is all the hill you have, you will get up it with a big load of kids. If you get to the top and cant touch the hub without cooking your hand, then you should drill some holes in the covers. They won't cool the hub that much, but once hot, it will be allowed to cool quicker than if sealed, and by smell, you will be able to tell when you are pushing it too hard.

At 450 pounds, you maximum you could do is a hill about 500 feet vertical, in a mile.

I'm not guessing this shit, I did extensive testing of this type motor, so E-bikekit would be able to put sensible limitations on their warranty. Quickest I ever cooked one off was about 15 min, but that took 4000w. At 1000w, you generally always have 30 min to an hour before one melts. In fact, I never did actually melt one down on 48v. I just got them hotter than they should be getting, and stay in warranty.

Again, the load they can easily take goes up to 400 pounds in a 20" wheel. There are lots of adult size bikes with 20" wheels. Consider getting one of those for your pull trailer bike. The 20" wheel, if you have some gears, will help you with pedaling too, same cogs on the chain will be a lower gear. Something like this would be ideal.
P8210010.JPG

EbikeAus   100 W

100 W
Posts: 287
Joined: Feb 04 2018 5:58am

Re: Would a 1500w Direct Drive Hub Get Me Up Short but Steep Hills on Full Suspension Bike without frying?

Post by EbikeAus » Mar 08 2019 10:43pm

itsallwhite wrote:
Mar 05 2019 4:11am
EbikeAus wrote:
Mar 05 2019 3:58am
itsallwhite wrote:
Mar 04 2019 6:49pm
EbikeAus wrote:
Mar 04 2019 6:11pm
I have the 48v (battery is 52v) 1000w rear hub kit and find it ok for hill climbing.. As long as you can get a decent run up.
Mine is throttle only, so I imagine with a bit of leg work it should be ok
Is it a regular ebay type kit or is it a slow wind / lower RPM kit for hill climbing?
Just the regular eBay one.
Has voilamart printed on it. I love it, best $250 I ever spent. I have around 500km on it now
Great to hear, what kind of hills have you got up with it? Anything off road / steep? Does it lose speed and bog down if you don't have a run up?
Hi
I would say the hills I go up are moderately steep and off road (gravel).
It definitely bogs down without a run up
Choose LiFe 8)

May all your batteries be fully charged and perfectly balanced :P

AHicks   1 kW

1 kW
Posts: 397
Joined: Jul 24 2018 10:53am

Re: Would a 1500w Direct Drive Hub Get Me Up Short but Steep Hills on Full Suspension Bike without frying?

Post by AHicks » Mar 09 2019 8:21am

I went back and read the original note again. With the gravel surfaces, the hills, the kids, and no mention of necessary extended higher speed runs mentioned, my vote for the proper hub motor here is geared. There is no down side to it when the conditions mentioned are in play. OTOH, the DD hub will have noticeably less torque available (as proven out on the simulator). With no need for speeds over 20mph, the DD offers no advantages over the gear drive. Bucks spent for bang received here, I would check out the MAC 12T (my vote).

User avatar
itsallwhite   100 mW

100 mW
Posts: 36
Joined: Feb 07 2019 5:02am

Re: Would a 1500w Direct Drive Hub Get Me Up Short but Steep Hills on Full Suspension Bike without frying?

Post by itsallwhite » Mar 10 2019 4:27am

Thanks everyone for your useful, thoughtful and helpful comments - so much knowledge here! Going to do a bit more thinking and a bit more research before making the plunge!

Torn between just giving one the cheaper 1000w DD ebay systems a shot and seeing what happens, or spending a bit more and going for a geared motor like the Mac 12t (I can't run a high powered 2000w+ DD on the battery I have).
Bike 1: Giant Hybrid Steel Frame (old) with TSDZ2 48v 500w.
Bike 2: GT Sensor 2 full suspension mountain bike. Work in Progress - ready to 'electrify'!
House: 100% off grid - 5.6kw solar array with selectronics inverter and 24 Volt 1450 Ah BAE Gel battery Bank

AHicks   1 kW

1 kW
Posts: 397
Joined: Jul 24 2018 10:53am

Re: Would a 1500w Direct Drive Hub Get Me Up Short but Steep Hills on Full Suspension Bike without frying?

Post by AHicks » Mar 10 2019 7:12am

Yup! Not many of us can. Pretty much the same reason I'm seriously considering the Mac 1500w 12t.

"I can't run a high powered 2000w+ DD on the battery I have"

User avatar
dogman dan   100 GW

100 GW
Posts: 35849
Joined: May 17 2008 12:53pm
Location: Las Cruces New Mexico USA

Re: Would a 1500w Direct Drive Hub Get Me Up Short but Steep Hills on Full Suspension Bike without frying?

Post by dogman dan » Mar 10 2019 8:46am

FWIW, time to overheat for any DD is about 4 times longer than any geared. That's why I tested the geared motor to fail in less than 30 min, when overloaded. The geared motors shed the heat poorly, and the amount of copper handling 1000w is half the weight. So they get hot twice as fast, just on the thermal mass alone.

Almost none of you commenting have any experience, or did real tests with overload. So what your geared hub does for you on a normal load has nothing to do with what will happen when you pull 400 pounds combined total weight up steep hills. Load is everything with hub motors, EBK needed to know what the critical load would be, since they offered a year of warranty on the kits, vs a few days for the cheap vendors. So we set out to find out definitively, and melted some motors doing it. We found the geared motor easy to melt down, but near impossible when the load is kept below 300 pounds, and grades do not exceed 10%.


Geared for the win though, if the load is only 250-300 pounds. My off road bike climbs the steepest grades I ride, and its running 1000w of geared, (48v 22 amps) in the 10t wind. . One hill is about 30%, but only for about 400 feet. It struggles like hell on it, but its short so the thing does fine. On that trail, much of the grade is about 10-15%, and I ride till the battery is nearly used up, then turn for the car. An hour of climbing, near non stop, at very steep grades. Lightly loaded with just me on a 70 pound bike, it gets very warm, but never overheats. Its all because the geared motor has great torque, and its not overloaded.


But when I hooked up the trailer and headed up the big road test hill weighing 400 pounds, I never even got to the 5% part of the hill with the geared motor. ( top of it 8%) I fried that thing on the 3% section that is two miles long. The exact same test with the 9 continent type DD motor got to the top, but was good and hot by then. Made it though! That hill starts at my house with 5 miles of 1%, then two miles of 3%, two miles of 5%, and lastly a mile and a half of 8%. The geared motor only got 6 miles up the road and then melted down.

Your load and a cheap 1000w dd kit will make it up your shorter hills. It will get hot, but likely make it. Drill some holes so the thing cools quicker, and does not cook your hall sensors when you stop. When you stop, you lose that wind cooling. Just a few holes will let some cool air in when you stop, cooling the halls before they get to 300F, and fail.

User avatar
itsallwhite   100 mW

100 mW
Posts: 36
Joined: Feb 07 2019 5:02am

Re: Would a 1500w Direct Drive Hub Get Me Up Short but Steep Hills on Full Suspension Bike without frying?

Post by itsallwhite » Mar 10 2019 9:27pm

Another option would be to attempt to install my TSDZ2 mid drive somehow on the bike (GT Sensor 2).

I think the bottom bracket thread is the right size, but because of the design its almost 'floating'.

Someone posted some pics of the bottom bracket on another ebike forum - not sure how / where motor would fit...?

https://electricbike.com/forum/forum/bu ... ion-sensor
Bike 1: Giant Hybrid Steel Frame (old) with TSDZ2 48v 500w.
Bike 2: GT Sensor 2 full suspension mountain bike. Work in Progress - ready to 'electrify'!
House: 100% off grid - 5.6kw solar array with selectronics inverter and 24 Volt 1450 Ah BAE Gel battery Bank

Post Reply