San Francisco Cargo bike

hi all,
I bought a Taga 2.0 without a motor to scoot around on in the city with my kids. Living in San Francisco, this 3 geared trike does not go up most of the hills i encounter. I can get the thing up most of the hills if the kids arent in it, for reference on how much pedal power i can give it, if that helps.
I have been researching a bit on what to buy, and I am getting quite confused by the various opinions, and tools.

Many people here and most people elsewhere (e.g. reddit) suggest a mid drive for sustained hills.
Some people here suggest a direct drive hub for hills if you have a 20" wheel and can set it to SLOW. But it's not clear exactly what that means, is that something i can do with the software of a hub motor controller? or is that something that is in the design of the internals?

I see loads of families in SF with cargo bikes and it appears most are mid drive, with some hubs, and Ive seen them handling the hills ok. but perhaps the extreme wear is shortening the life of their motors, so this anecdotal evidence is misleading?

In trying to determine if a motor could handle an outing that i would like to take with my kids, I tried using the ebike tools.

For example. Here is a Trip simulator (hope the link works) through San Francisco that shows most motors failing for this route. However, the BBS02 & BBSHD handle it seemingly ok?

However, if i use the motor simulator to see how quickly the two Bafang mid drives handle a 20% grade they show overheating in a few minutes.

Is the trip simulator accurate in this scenario? I guess the >20% graded sections along the route are very short, so overheating theoretically never occurs?

So, to sum up, what is the best setup for me here. I don't care about going to fast, there are bike lanes in most places in SF. I just want to get around with my kids and up these hills reliably and for a long time to come.

Details asked for in the sticky
Desired max speed on level ground: <20 mph
Desired max range at what cruising speed: 10 miles (should cover most round trips in the city)
Wheel size: 20"
Brake type of motor wheel: disc on front, drum on back
Rider weight. 175 lbs. two kids: 60 lbs and growing
Terrain: very hilly in SF. 20% grade not uncommon.
Budget: <1000$

mol3earth said:

Some people here suggest a direct drive hub for hills if you have a 20" wheel and can set it to SLOW. But it's not clear exactly what that means, is that something i can do with the software of a hub motor controller? or is that something that is in the design of the internals?

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Most likely they are referring to the design of the internals called the Winding. They are various motor windings a person can choose from ranging from slow to fast. Usually the fast windings are paired with the small diameter wheels. However, when working with the typical voltage limit of 48v (or 52v) the slower winding used with a smaller diameter wheel results in greater and more efficient climbing ability (on steep hills) at the cost of top speed on flat ground.

With that mentioned any wheel diameter and any winding speed combination can hypothetically be good at either climbing or top speed. It is just a matter of using the right combination of volts and amps. However, I mention slow winding with small diameter because the hardware infrastructure of controller, phase wires, etc is locked into (for the most part) a certain limitwd range of volts and amps.

Back when I worked in SF, the folks who cycled / commuted with family cargo bikes and trikes liked using the Bafang 750 watt mid-drive and wide range gearing.
Should the gearing change not be an option then at least use a smaller front crank sprocket to lower the gear ratio to help climb the hills.

PaPaSteve said:

Bafang 750 watt mid-drive and wide range gearing.

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that's the BSS02, yea? or does it not matter between HD and 02?

PaPaSteve said:

Should the gearing change not be an option then at least use a smaller front crank sprocket to lower the gear ratio to help climb the hills.

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what front sprocket would you suggest, in the case I wont add gearing?
also, ive seen people caution against gearing, or at least talk about how you have to turn off your motor while shifting. that is gonna be really annoying with all the hills around here. sticking to the internal gears is ideal.
would getting an 8 speed internal gear rear tire be enough?

TBH, I would love to add gearing and see if I can just tackle the hills myself. but this trike is a bit weird in that it has the hub brake. so adding gearing means getting an entire new wheel and then figuring out how to mount a disc brake. Not that tricky, but a fair amount of parts.
but if making this work long term with a mid drive means adding gearing, then that's fine.

ebike4healthandfitness said:

Most likely they are referring to the design of the internals called the Winding. They are various motor windings a person can choose from ranging from slow to fast. Usually the fast windings are paired with the small diameter wheels. However, when working with the typical voltage limit of 48v (or 52v) the slower winding used with a smaller diameter wheel results in greater and more efficient climbing ability (on steep hills) at the cost of top speed on flat ground.

With that mentioned any wheel diameter and any winding speed combination can hypothetically be good at either climbing or top speed. It is just a matter of using the right combination of volts and amps. However, I mention slow winding with small diameter because the hardware infrastructure of controller, phase wires, etc is locked into (for the most part) a certain limitwd range of volts and amps.

Click to expand...

yea, that's what it was, winding. thanks!

it appears most of these are custom builds, as opposed to something you can get off the shelf?

mol3earth said:

yea, that's what it was, winding. thanks!

it appears most of these are custom builds, as opposed to something you can get off the shelf?

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Usually, there will be several different winds available without going custom.

Usually "fast wind", "standard wind" and "slow wind".

Sometimes just two winds for a particular motor.

But yeah, but if you wanted something extreme beyond that you could always go custom. Some OEMs if you order direct from them won't even charge you any extra for a custom winding. (e.g. leaf bike)

Have you used the bikes.ca motor calculator yet:


With that simulator you can plug in different motors and different motor windings then test on flat ground and up various grades.

Mol3earth,

Do you happen to know the rear spacing on your frame? This is the space where the rear hub sits.

Is it 135mm?

P.S. I noticed the factory electric kit for the Taga 2.0 (back in 2017) was a single speed freewheel plus disc brake on the hub motor:
So it might be 135mm but it could also be something else. Hopefully it is 135mm as that will make motor selection easier.

Leaf Bike will custom wind a motor to run at the RPM you specify. So if you know how fast you want to go, what wheel diameter, and what voltage you want to run at, then they will recommend a custom winding to suit. Limiting the road speed without limiting the gross power means more torque for scaling hills. 1500W that maxes out at 20mph would make for a serious amount of push at 10mph.

ebike4healthandfitness said:

Mol3earth,

Do you happen to know the rear spacing on your frame? This is the space where the rear hub sits.

Is it 135mm?

P.S. I noticed the factory electric kit for the Taga 2.0 (back in 2017) was a single speed freewheel plus disc brake on the hub motor:

So it might be 135mm but it could also be something else. Hopefully it is 135mm as that will make motor selection easier.

Click to expand...

thanks for that. yes, it is 135mm. the trickier part is finding a discc brake adapter that will work for the bike. i will tackle that when/if i need to.
the taga kit is a 250w bafang rear hub, so i doubt the "official" taga option is going to work for me in SF. but the single speed isnt the problem is it? a rear hub "ignores" the gear, i've been told.

Let us know what exact bike you bought because I try to look it up and it wouldn't let me all it would let me see was their electrified version two wheels in front one wheel and back. How much money do you want to spend.

mol3earth said:

a rear hub "ignores" the gear, i've been told.

Click to expand...

The motor does its thing separately from the chain drive, so yeah, it is unaffected by gear ratio. But... very low gearing or very hard pedaling can break the freewheel thread off of the motor's side cover.

mol3earth said:

thanks for that. yes, it is 135mm. the trickier part is finding a discc brake adapter that will work for the bike. i will tackle that when/if i need to.
the taga kit is a 250w bafang rear hub, so i doubt the "official" taga option is going to work for me in SF. but the single speed isnt the problem is it? a rear hub "ignores" the gear, i've been told.

Click to expand...

Near the end of the Taga electric kit video I linked they show a disc brake adapter being added. Hopefully Taga sells that as a separate part. If they do they you will be good to go if you want use disc brake.

Yes, a hub motor works the same whether the pedal drive train is single speed or multiple speed.

Not sure how much you have played with the ebikes.ca motor simulator but I would also consider leaf bike 1500w/2000w (i.e. the 35mm wide stator version of the motor that makes a dish-less wheel on 135mm rear spacing with single speed freewheel and disc brake). This motor is also found in the simulator. Trouble is there is no US distributor yet so you would have to source from China and not only that shipping is expensive. Still for 135mm, single speed freewheel and disc brake it would be my goto --> Leaf / leafmotor / leafbike high efficiency 1500w motor (note: you can get that motor with a bicycle rim or smaller moped rim as well)

P.S. Another thing to consider as far as rear braking goes is Regen. If your controller is Regen enabled it enables your direct drive hub to function as a brake (while also flowing some energy back into the battery). This braking effect (from activating Regen) is separate from the braking caused by the rear disc. With that mentioned not sure how effective rear braking will be on that tadpole cargo trike going down a SF Hill! But it is good to have none the less as rear brake should allow you to save wear and tear on front brakes when stopping on flat ground or on more gentle hills.

Chalo said:

Leaf Bike will custom wind a motor to run at the RPM you specify. So if you know how fast you want to go, what wheel diameter, and what voltage you want to run at, then they will recommend a custom winding to suit. Limiting the road speed without limiting the gross power means more torque for scaling hills. 1500W that maxes out at 20mph would make for a serious amount of push at 10mph.

Click to expand...

hmm, that's interesting. since it is still a hub motor, there is a grade that the motor will not like, yea? or is that so high that you would fall off before that point?

Chalo said:

The motor does its thing separately from the chain drive, so yeah, it is unaffected by gear ratio. But... very low gearing or very hard pedaling can break the freewheel thread off of the motor's side cover.

Click to expand...

999zip999 said:

Let us know what exact bike you bought because I try to look it up and it wouldn't let me all it would let me see was their electrified version two wheels in front one wheel and back

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sorry, should have done that in the original post here it is Taga Family-Cargo Bike Duo Seater - Taga Bikes

or look at the ad on the kickstarter for more details https://www.kickstarter.com/projects/taga2/taga-20-the-ultimate-most-affordable-family-bike

the electric is the same as the non-electric. with the exception that either the pedals have a pendix mid-drive, or the rear wheel has a rear-hub.

you can buy a kit from them (listed on their site) to convert what i have to be electric. my bike has the mounting stuff attached.

. How much money do you want to spend.

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i would like to spend <$1000.

ebike4healthandfitness said:

Near the end of the Taga electric kit video I linked they show a disc brake adapter being added. Hopefully Taga sells that as a separate part. If they do they you will be good to go if you want use disc brake.

Click to expand...

they don't sell that adapter separately. it is only included with the rear wheel electric kit.

ebike4healthandfitness said:

Not sure how much you have played with the ebikes.ca motor simulator but I would also consider leaf bike 1500w/2000w (i.e. the 35mm wide stator version of the motor that makes a dish-less wheel on 135mm rear spacing with single speed freewheel and disc brake). This motor is also found in the simulator. Trouble is there is no US distributor yet so you would have to source from China and not only that shipping is expensive. Still for 135mm, single speed freewheel and disc brake it would be my goto --> Leaf / leafmotor / leafbike high efficiency 1500w motor (note: you can get that motor with a bicycle rim or smaller moped rim as well)

Click to expand...

shucks. 378 + 124 shipping is for just the rear wheel is almost what a mid drive kit costs. and since this is a 60V hub, i need a 60V battery?

the ebikes motor simulator is pretty confusing to me, as i dont really understand some of the parameters. which motor is the 2000w leaf? the only leaf i see in the drop down is "Leaf 35mm 5T" and when i use that one to see when it overheats it says "Not modelled" and final temp is "NA"

ebike4healthandfitness said:

P.S. Another thing to consider as far as rear braking goes is Regen. If your controller is Regen enabled it enables your direct drive hub to function as a brake (while also flowing some energy back into the battery). This braking effect (from activating Regen) is separate from the braking caused by the rear disc. With that mentioned not sure how effective rear braking will be on that tadpole cargo trike going down a SF Hill! But it is good to have none the less as rear brake should allow you to save wear and tear on front brakes when stopping on flat ground or on more gentle hills.

Click to expand...

the regen is handled by the controller? or do you need something else?
any breaking to help save the front brakes would be nice, for sure.

great post, thanks for all the info

You've got the perfect wheel size for a DD hub motor.

Motor Simulator - Tools



The above configuration will just barely take those hills without melting while pedaling like a madman, and the motor is also a lot cheaper than a mid drive. And about 12lbs, not bad. You have 10 minutes of this torture until it melts. Putting in ferrofluid would probably double that that meltdown time to 20 minutes.

The secret sauce is the taller stator than most DDs, and a higher pole count. Because of this, you don't need a 16lbs leafmotor.

This motor wouldn't have a high top speed unless you went above 48v but it would take off like a rocket and shrug off a majority of hills.

Regenerative braking could be tuned to be extremely strong and make the descents nice and easy.

Yeah, you could use a mid drive, but you need one that could output ~1.5kw to get up this hill at anything like a reasonable speed. It would cost a lot more and there'd be a lot more parts to break.

Normally i'd advise you use a GMAC 8T, but it melts faster in this simulation. That 20% grade is a real challenge for any motor to get up.

Neptronix,

When I plug in the same parameters you used into the ebikes.ca motor simulator but use Leaf 5T 35mm instead of RH212 Std I get a faster climbing of 15.4 mph this despite the Leaf 5T having a much higher Kv of 10.5 compared to the RH212 Std Kv of 8.2.

If I change the Kv of the Leaf motor to match your motor's Kv the climbing performance under the same conditions does drop to 15.0 mph but that is still better than the 14.2 mph you are getting with RH212 Std.

Personally I think a bigger motor is needed.

If she is not intending to use disc brake and instead will use Regen the bigger motor will help that as well.

Based on that I would be thinking Leaf 42mm as a possible next step. This especially as it keeps the dish-less wheel and is a true 135mm product like the 35mm leaf single speed. Top bad nobody has tested that one yet!

Another option is a mid drive, but that risks a wide and unequal q factor which may not be conducive to pedaling. This especially if the OP's legs are on the short side (Wide q factor is worse biomechanically the shorter the leg length gets.)

Extra 1.2mph on <5% of the ride for another 4lbs. not really worth it.

The specified battery is the limit in regenerative braking power and not the motor, the motor has 1.5kw of braking power possible, but we don't have room for a massive battery which could actually take in that amount of power.

Regen would be a hundred times safer than a disc brake descending down a 20% grade and a lot more powerful than the biggest disc brake you could buy even if at a 750w limit. Good idea to use it - it won't fade like a friction brake will. Any friction brake will massively fade going down 20%, it's an incredible amount of energy to turn into heat; turn it into battery power instead.

$1,000 I got an option. 135mm rear ?

Here's the kit you're going to have to talk to him about a 20-in rim but it's a 135 mm.axle and 45mm stator harder to melt. I paid 345.00 USD the downside is you have to know what you want and talk to him and get it in print and pay with PayPal for protection. Remember it is China. Tighten the spokes through the rim before you put it on. By the time you find a charger$700 !!!

PS wait what kind of rear brake do you have on there the kid I showed you only has disc brake you have to ask him if you can have a 20-in rim with a rim brake or what type of break do you have on the rear ?

Here's the battery you're going to have to get a BMS and a charger. But the cells inside. Great.
On paper. Get a Bluetooth BMS..

neptronix said:

Extra 1.2mph on <5% of the ride for another 4lbs. not really worth it.

Click to expand...

No, I'm not suggesting she use the Leaf 35mm motor. I think she needs to be looking at a DD with at least a 42mm wide stator.

The bigger motors greater efficiency at low speed and light throttle also means her Regen efficiency at low speed and light regen will be higher. So if she going very slow down a steep hill at low watts Regen her efficiency at capturing energy will be higher with a 42mm or wider motor than what it would be with a 35mm motor.

999zip999,

The bike has a 135mm single speed rear hub with integrated drum brake (I'm guessing Sturmey Archer).

Correction: Bike has a Shimano Nexus 3 speed with roller brake.

As far as equipping rear disc brake Taga does make a rear disc adapter which it includes in its electric assist kit....but does not sell this adapter separately according to the OP.

Not sure if there are provisions on the frame for a rim brake. I didn't look for that when I was watching the video.

You'd really add another 10lbs of motor weight and spend 2x on the motor to optimize a couple % efficiency in an edge case condition?

I wouldn't. And i wouldn't recommend any sane person do that

The kit I mentioned above has a weatherproof controller but it doesn't have region capabilities on the 72 volt kit maybe things have changed maybe they have regen now but they only had disc brake make sure if you have a rim brake the side of the rim is machined for brake pads. Before you buy tell us what rim it comes with it and any other questions before you buy. Make a box the size of that battery and see where you going to put it along with the controller. That way you know where everything fits.