Bike Range - DD VS. Geared Hub

M

MattZ

100 W
Joined
Jul 14, 2021
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All things being equal besides the hub, would a direct drive hub go a longer distance than a geared hub of the same wattage rating?
I'm thinking of swapping out a DD hub for a geared hub. Mostly ride on flat rail trails and greenways, some roads. Minor short hills, no long steep inclines. Tend to go relatively slow, 15 to 25 mph tops. Total weight of bike and rider is about 200 lbs. Battery is 48v, 20Ah.
I know a geared hub will spin 5X more, but I'm thinking the RPMs will be in a more efficient range. Looking for more torque but not if it has a high price in range.
 
Great question! From the parameters you describe in your normal ride, I think range of DD vs Geared would be so close as to be insignificant.
The variable that might make a difference is number of starts and stops. Very large number of starts = technical advantage to Geared. Very low number of starts = technical advantage to DD. But in real world, with a 48V / 20Ah battery ... plenty of range with either motor. Wiser heads may be able to tell us more, but my gut feeling is we are talking a difference of a maybe few hundreds yards in total range between the two.
 
MattZ said:
All things being equal besides the hub, would a direct drive hub go a longer distance than a geared hub of the same wattage rating?
I'm thinking of swapping out a DD hub for a geared hub. Mostly ride on flat rail trails and greenways, some roads. Minor short hills, no long steep inclines. Tend to go relatively slow, 15 to 25 mph tops. Total weight of bike and rider is about 200 lbs. Battery is 48v, 20Ah.
I know a geared hub will spin 5X more, but I'm thinking the RPMs will be in a more efficient range. Looking for more torque but not if it has a high price in range.
Click to expand...

It's going to depend more on the efficiency of the motor and the speed where they are most efficient, more than whether it's geared or not. When powered, I don't think there will be much difference under the conditions described. When not powered, the geared drive has the advantage of better coasting, while the direct drive has the potential to provide regen, both of which extend range.

I'm without regen right now since I'm using my spare controller, so I've been messing around with pedaling (PAS) and coasting, and throttling and coasting to see how low I can get my Wh/mile, and also applying a tiny bit of throttle so the motor freewheels and coasts further. I guess the point is, you could optimize the range based on your riding technique, which may be different between a geared and DD hub.
 
I've done this exact swap. I swapped a 1000w Leaf DD hub for a 1000w MAC 12t geared hub. All else remained the same, even the KT 35 amp controller.

For my purposes, I will never own another DD. HUGE difference in performance in the 0-15mph range where I spend most of my time. Way better accelerating from a stop (you had better be holding on with both hands), and a major difference in it's ability to climb.

Further, the DD hub struggled to make 30 miles using the 14ah battery. SAME battery with the MAC geared hub had no trouble making 35 miles consistently.

No brainer here.....
 
footloose said:
Great question! From the parameters you describe in your normal ride, I think range of DD vs Geared would be so close as to be insignificant.
The variable that might make a difference is number of starts and stops. Very large number of starts = technical advantage to Geared. Very low number of starts = technical advantage to DD. But in real world, with a 48V / 20Ah battery ... plenty of range with either motor. Wiser heads may be able to tell us more, but my gut feeling is we are talking a difference of a maybe few hundreds yards in total range between the two.
Click to expand...

Thanks, that makes perfect sense
 
Along the comparison between the two I've found DD to be virtually silent and geared drives to be a bit noisy. Is it just the drives I've encountered with my limited exposure or does this hold true for the market in general?
 
E-HP said:
It's going to depend more on the efficiency of the motor and the speed where they are most efficient, more than whether it's geared or not. When powered, I don't think there will be much difference under the conditions described. When not powered, the geared drive has the advantage of better coasting, while the direct drive has the potential to provide regen, both of which extend range.

I'm without regen right now since I'm using my spare controller, so I've been messing around with pedaling (PAS) and coasting, and throttling and coasting to see how low I can get my Wh/mile, and also applying a tiny bit of throttle so the motor freewheels and coasts further. I guess the point is, you could optimize the range based on your riding technique, which may be different between a geared and DD hub.
Click to expand...

That's interesting, and good advice about optimizing range through technique. I assume it's a quirk of my controller, (a 45A, 12 FET KT sine wave) that if I coast with anything more than zero throttle there's a drag like what I assume regen would feel like, even though it's turned off in the settings. I've been meaning to turn regen on to see if it feels the same but haven't gotten around to it yet.
 
Diggs said:
Along the comparison between the two I've found DD to be virtually silent and geared drives to be a bit noisy. Is it just the drives I've encountered with my limited exposure or does this hold true for the market in general?
Click to expand...

I'm concerned about the noise as well, but I've never ridden a geared hub bike. The ones I've seen go by seem quiet but they're not kit bikes and have small motors. I'm considering getting an MXUS XF19R 1000w motor and there doesn't seem to be much information on them. There's a thread on here where one person says it's loud, and another says it's quiet but there's no conclusion either way. I assume there could be manufacturing variations that make sound level variations between motors. I did have a noisy DD motor on my first build and couldn't live with it. Trying different controllers, square wave, sine wave, all 36 combinations of hall / phase wires made no difference. The seller replaced it and the new one made the same racket. A different brand motor solved the problem.
 
AHicks said:
Way better accelerating from a stop (you had better be holding on with both hands), and a major difference in it's ability to climb.
Click to expand...

Second that. I have a MAC, 12T, 48V system. Lots of torque, it zooms. DD by comparison ... feels like it gives me time to plan my day and meditate for a while as it is getting up to speed. Not a bad thing, just different.
 
AHicks said:
I've done this exact swap. I swapped a 1000w Leaf DD hub for a 1000w MAC 12t geared hub. All else remained the same, even the KT 35 amp controller.

For my purposes, I will never own another DD. HUGE difference in performance in the 0-15mph range where I spend most of my time. Way better accelerating from a stop (you had better be holding on with both hands), and a major difference in it's ability to climb.

Further, the DD hub struggled to make 30 miles using the 14ah battery. SAME battery with the MAC geared hub had no trouble making 35 miles consistently.

No brainer here.....
Click to expand...
Thanks, that's real good info. I didn't suspect you'd get more range with a geared hub. You went with a high end motor, I'm just looking at mid range but it's for my wife's bike and she won't test its upper limits. She does have a knack for chugging along slowly which tests the lower limits of that DD motor.
 
footloose said:
AHicks said:
Way better accelerating from a stop (you had better be holding on with both hands), and a major difference in it's ability to climb.
Click to expand...

Second that. I have a MAC, 12T, 48V system. Lots of torque, it zooms. DD by comparison ... feels like it gives me time to plan my day and meditate for a while as it is getting up to speed. Not a bad thing, just different.
Click to expand...

I'd be interested in the stats. If you could download the app "GPS Race Timer" and record the 0 to 30 MPH time of the MAC 12T, that would be a good data point. Using a DD Leaf, I get 0-30 in 3.8 seconds. DD QS205 on Eastwood's bike was 3.4 seconds. I'd love to try out a MAC, but they seem to be limited in the power they can handle.
 
MattZ said:
You went with a high end motor, I'm just looking at mid range but it's for my wife's bike and she won't test its upper limits. She does have a knack for chugging along slowly which tests the lower limits of that DD motor.
Click to expand...
Last bike I help build for a friend, we used the smaller Bafang 350W geared motor. It is pretty sweet. Might be perfect for your wife's build. Seems like over the years I'm actually appreciating lower-power builds more than higher-power builds. Could be I'm getting more sense with age, could just be that I'm now well into my old-fart-hood.
 
Might want to consider the weight difference as well. I am guessing that for the same power a geared drive is going to be smaller and lighter than a DD. As regards noise: plastic beveled gears are quieter than metal straight cut gears.
 
LewTwo said:
Might want to consider the weight difference as well. I am guessing that for the same power a geared drive is going to be smaller and lighter than a DD. As regards noise: plastic beveled gears are quieter than metal straight cut gears.
Click to expand...

I can't imagine the weight difference wouldn't be significant. That 1200w DD on there now could do double duty as a boat anchor, on an oligarch's yacht.
 
MattZ said:
I can't imagine the weight difference wouldn't be significant. That 1200w DD on there now could do double duty as a boat anchor, on an oligarch's yacht.
Click to expand...
So you are saying the you have an "anchor chain" as well ...




sorry .... I could not resist the temptation :twisted:
 
footloose said:
Last bike I help build for a friend, we used the smaller Bafang 350W geared motor. It is pretty sweet. Might be perfect for your wife's build. Seems like over the years I'm actually appreciating lower-power builds more than higher-power builds. Could be I'm getting more sense with age, could just be that I'm now well into my old-fart-hood.
Click to expand...
You make a good point. I'm finally realizing more power = more expensive + more weight + more breakage. I think I'll tone down the wattage on the new motor. Plus I get out of the nightmare of switching from the smaller Julet connector on there now to the larger one that comes on the 1000w motor.
 
Regarding the "wife's bike". I don't know what you are looking at for hills in your area, but we have some pretty significant stuff in one of the areas we frequent. Nothing real long, but some are pretty steep (rolling coastal hills). I set her up on a Bafang 500w geared hub drive, coupled with a KT-22a controller. This is an AWESOME set up! She's somewhere around 125 lbs, and can make any hill I can with my much more powerful bikes. Why? Because that controller is able to feed that 500w motor with close to 1000 watts. It gets REAL sporty on that kind of power! The downside is you need to be smart about it. Clearly you are feeding twice it's rated power into it, and it's only going to handle that for a few seconds prior to getting HOT! I was so impressed I built one for myself for use in an area that's mostly level. 55lbs all up with a 14ah battery so handling is awesome.
 
E-HP said:
footloose said:
AHicks said:
Way better accelerating from a stop (you had better be holding on with both hands), and a major difference in it's ability to climb.
Click to expand...

Second that. I have a MAC, 12T, 48V system. Lots of torque, it zooms. DD by comparison ... feels like it gives me time to plan my day and meditate for a while as it is getting up to speed. Not a bad thing, just different.
Click to expand...

I'd be interested in the stats. If you could download the app "GPS Race Timer" and record the 0 to 30 MPH time of the MAC 12T, that would be a good data point. Using a DD Leaf, I get 0-30 in 3.8 seconds. DD QS205 on Eastwood's bike was 3.4 seconds. I'd love to try out a MAC, but they seem to be limited in the power they can handle.
Click to expand...

Regarding "stats" you should be able to get anything you need from the Grin Chart. Look at "starting torque" first...
Keep in mind we're on 48v here. A stock 48v battery as supplied in a RAD production bike. I think it quite a stretch you're making 30mph in 3.8 seconds on 48v with a DD.

Everyone likes to brag up what can be done with a DD, but they frequently leave out exactly how they are doing it. Details like the battery voltage for instance.....

And don't take that wrong. DD is the plan for higher speeds and big power. They really struggle though, in the 0-15mph a lot of folks like to play in using 48v.

The MAC does fine with a 35a controller. Mine is still going strong at 7 years old and 3500 miles. During that time, I've had zero interest in seeing how much more power it can/would handle. This motor is rarely run over 15mph....

And anyone that tries to say that geared hubs are noisier than a DD likely has no experience on both. That's simply not true.
 
AHicks said:
Regarding "stats" you should be able to get anything you need from the Grin Chart. Look at "starting torque" first...
Keep in mind we're on 48v here. A stock 48v battery as supplied in a RAD production bike. I think it quite a stretch you're making 30mph in 3.8 seconds on 48v with a DD.

Everyone likes to brag up what can be done with a DD, but they frequently leave out exactly how they are doing it. Details like the battery voltage for instance.....

And don't take that wrong. DD is the plan for higher speeds and big power. They really struggle though, in the 0-15mph a lot of folks like to play in using 48v.

The MAC does fine with a 35a controller. Mine is still going strong at 7 years old and 3500 miles. During that time, I've had zero interest in seeing how much more power it can/would handle. This motor is rarely run over 15mph....

And anyone that tries to say that geared hubs are noisier than a DD likely has no experience on both. That's simply not true.
Click to expand...

Well this is way off topic, and the motors are different, so of course if you place limitations on one or the other that are not physical limitations, you'll get different results. If you only apply the physical limitations of each motor and their performance, that would be their capability. I'm still interested in the MAC's real world performance, under whatever stated voltage or current you provide it.

They are both electric motors, so you provide them power and they perform. Provide more power, performance goes up. So, you just provide as much power for the desired performance. They both have a limit on now much power they can take without melting or breaking. The tolerance to take more power is higher for a DD hub than a geared hub, due to mechanical factors (gears) and heat dissipation. Both of those favor the DD, hence they can take more power and have higher potential performance.

I'm interested in how the MAC performs when provided power that is at it's upper limit. I know I'm far from the upper limit of my Leaf motor, based on what others have provided it. There was also a comment on climbing hills, but I'm pretty sure the DD will climb a steeper and longer hill than a MAC (based on the simulator, the MAC 12T melts on a 20% hill, >250C in 3.3 minutes at 11.1 mph, so that's no contest, but the acceleration part is interesting, so specs would be cool.

If you have a temp sensor, some temp specs on a steep climb would be interesting as well. But I couldn't use a MAC for my purposes, because of the hills.
https://ebikes.ca/tools/simulator.html?motor=Leaf%205T&batt=cust_80_0.05_24&cont=cust_70_200_0.03_V&hp=0&axis=mph&frame=mountain&autothrot=false&throt=100&grade=20&wheel=25i&mass=110&bopen=true&cont_b=C35&motor_b=MMAC12T&batt_b=B4823_AC&wheel_b=25i&mass_b=110&hp_b=0&grade_b=20

This hill would take the about 5 minutes for the MAC 12T to climb, so it would melt halfway up, >250C. The Leaf climbs it in under 3 minutes, partial throttle at 20mph, and was at 99C at the top. I don't ride fast, but I like acceleration, and I have steep hills, so DD works for me; but still interested in the MAC's acceleration since at some point I may move somewhere flatter.
https://www.youtube.com/watch?v=XL43hUrt9EE
 
E-HP said:
AHicks said:
Regarding "stats" you should be able to get anything you need from the Grin Chart. Look at "starting torque" first...
Keep in mind we're on 48v here. A stock 48v battery as supplied in a RAD production bike. I think it quite a stretch you're making 30mph in 3.8 seconds on 48v with a DD.

Everyone likes to brag up what can be done with a DD, but they frequently leave out exactly how they are doing it. Details like the battery voltage for instance.....

And don't take that wrong. DD is the plan for higher speeds and big power. They really struggle though, in the 0-15mph a lot of folks like to play in using 48v.

The MAC does fine with a 35a controller. Mine is still going strong at 7 years old and 3500 miles. During that time, I've had zero interest in seeing how much more power it can/would handle. This motor is rarely run over 15mph....

And anyone that tries to say that geared hubs are noisier than a DD likely has no experience on both. That's simply not true.
Click to expand...

Well this is way off topic, and the motors are different, so of course if you place limitations on one or the other that are not physical limitations, you'll get different results. If you only apply the physical limitations of each motor and their performance, that would be their capability. I'm still interested in the MAC's real world performance, under whatever stated voltage or current you provide it.

They are both electric motors, so you provide them power and they perform. Provide more power, performance goes up. So, you just provide as much power for the desired performance. They both have a limit on now much power they can take without melting or breaking. The tolerance to take more power is higher for a DD hub than a geared hub, due to mechanical factors (gears) and heat dissipation. Both of those favor the DD, hence they can take more power and have higher potential performance.

I'm interested in how the MAC performs when provided power that is at it's upper limit. I know I'm far from the upper limit of my Leaf motor, based on what others have provided it. There was also a comment on climbing hills, but I'm pretty sure the DD will climb a steeper and longer hill than a MAC (based on the simulator, the MAC 12T melts on a 20% hill, >250C in 3.3 minutes at 11.1 mph, so that's no contest, but the acceleration part is interesting, so specs would be cool.

If you have a temp sensor, some temp specs on a steep climb would be interesting as well. But I couldn't use a MAC for my purposes, because of the hills.
https://ebikes.ca/tools/simulator.html?motor=Leaf%205T&batt=cust_80_0.05_24&cont=cust_70_200_0.03_V&hp=0&axis=mph&frame=mountain&autothrot=false&throt=100&grade=20&wheel=25i&mass=110&bopen=true&cont_b=C35&motor_b=MMAC12T&batt_b=B4823_AC&wheel_b=25i&mass_b=110&hp_b=0&grade_b=20

This hill would take the about 5 minutes for the MAC 12T to climb, so it would melt halfway up, >250C. The Leaf climbs it in under 3 minutes, partial throttle at 20mph, and was at 99C at the top. I don't ride fast, but I like acceleration, and I have steep hills, so DD works for me; but still interested in the MAC's acceleration since at some point I may move somewhere flatter.
https://www.youtube.com/watch?v=XL43hUrt9EE
Click to expand...

As mentioned, my interests lie in the 0-15 mph realm. Though I am frequently in an area with big rolling coastal hills, and it has had no trouble climbing them for the last 7 years while using just a minimum amount of power (PAS 2-3). That was the reason for replacing the DD motor to start with. The MAC is easily climbing hills running PAS 2-3, that would stall the Leaf DD.......

Another point, is the difference in how long it takes to melt is the voltage you're running. And speaking of voltage you haven't mentioned what you are running - typical of those running DD and talking performance numbers just as I mentioned earlier.

Last, let's consider 2 1000 watt motors, one a DD one a geared hub, running on 48v. The MAC, with it's 5:1 internal gearing, is going to have quite an advantage accelerating from a stop, wouldn't you think?
 
AHicks said:
Another point, is the difference in how long it takes to melt is the voltage you're running. And speaking of voltage you haven't mentioned what you are running - typical of those running DD and talking performance numbers just as I mentioned earlier.

Last, let's consider 2 1000 watt motors, one a DD one a geared hub, running on 48v. The MAC, with it's 5:1 internal gearing, is going to have quite an advantage accelerating from a stop, wouldn't you think?
Click to expand...

System A in the link is my exact setup. I'm interested in the 0-15 time just to get a feel for what you are experiencing.

A toyota corolla may been a ferrari in a race, if you limit the ferrari to the fuel flow of the corolla, so agree that running an arbitrary limit, rather than than based on physical limitations, will provide skewed results.
 
LewTwo said:
As regards noise: plastic beveled gears are quieter than metal straight cut gears.
Click to expand...

I think the marketing term is "helical gears". If one is to search for specifically that type of quiet motor.
 
Comrade said:
LewTwo said:
As regards noise: plastic beveled gears are quieter than metal straight cut gears.
Click to expand...

I think the marketing term is "helical gears". If one is to search for specifically that type of quiet motor.
Click to expand...

I wonder how much noise reduction there is, relative to straight cut steel gears, if they adapted PMG technology to geared motors?
https://blog.schunk-group.com/en/blog/powder-metal-gears-for-quiet-e-mobility

Seems like a potential to have the added strength of steel gears with some noise dampening properties, since different materials can be combined to make the gears.
 
How about a DD WITH middrive?
How about two middrives, one left-sided (RC single stage reduction), and one right-sided (conventional crank drive)? :)

You can have both for half the weight of a DD wheel, and get very low unsprung weight, high efficiency (and power!) at high speed cruise AND stump-pulling torque if you have wide range cassette. AND regen.
 
Comrade said:
LewTwo said:
As regards noise: plastic beveled gears are quieter than metal straight cut gears.
Click to expand...

I think the marketing term is "helical gears". If one is to search for specifically that type of quiet motor.
Click to expand...
Correct ... bevel cut gears are used in right angle drives (such as differentials).
My bad :oops:
 
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