San Francisco Cargo bike

[mol3earth]

In your situation with the rear brakes a mid drive might be the easiest way out. If it can fit with the interference from the bottom bracket that I read about ?

the mid drive (bafang bbs02) will fit if you cut away some of the metal near the pedals.
a number of people in a facebook group have reported doing this and a few years later have seen no signs of failure. reportedly california ebikes has done one of these conversions as well. so purportedly the frame can handle it?

i am obviously hesitant to attempt this.

 

[neptronix]

What did you think about my recommendation for a RH212 on the first page?

 

[999zip999]

I never heard of a bolt on disc brake adapter is there such a thing I'm trying to weld a torque arm to an old old mountain bike for disc brakes as the motor I got could only come for disc brakes and not a rim break option.

That rear brake on his bike makes for some limitations and now he has a bump on the bottom bracket what were they think of next ?

 

[999zip999]

Here's a pic of my truck arms that I'm going to weld onto a 1980 giant upland for rear brakes to match that Sali kit
I bought this kit because it was 50 shipped to my door in California and I was going in for knee operation and the mental community is a push me no the medical community in California is a brainless blind octopus with the suckers still working for years

 

[999zip999]

I hate my here's my disc brake conversion once I see if I can make them fit I don't know I think I just have to yank one side out and use a 180 disc or or 160 for the rear I don't know how these old MTB frames can accept a small rear disc brake attaching the motor. ??
There's a lot of work. ???

 

[mol3earth]

What did you think about my recommendation for a RH212 on the first page?

oh, sorry, i thought you were not recommending that build based on the comment "You have 10 minutes of this torture until it melts."

you also comment "it will take off like a rocket." what exactly does that mean? my kids might love the rocket like ride, but it seems a bit unsafe to me. Though i assume the throttle/peddle assist can be controlled to make the standing start more reasonable?

 

[mol3earth]

I never heard of a bolt on disc brake adapter is there such a thing I'm trying to weld a torque arm to an old old mountain bike for disc brakes as the motor I got could only come for disc brakes and not a rim break option.

That rear brake on his bike makes for some limitations and now he has a bump on the bottom bracket what were they think of next ?

there are loads of these things. Here is one that should work for my Taga

 

[999zip999]

Yes taking off like a rocket is the controllers that we all got 5 8 10 years ago that were very twitchy with the throttle which I don't think you would like or as taken off like a rocket. This is a true characteristic of electric motors as how to tame that so it's radical that's all


The Dali kit is a mellower start . Ok.
Your bike with it rear end would be better served without a big medium big dress drive motor as what the other people are suggesting I'm bowing out of that 3,000 watt motor because of his complications for your frame. Great.

 

[PaPaSteve]

the mid drive (bafang bbs02) will fit if you cut away some of the metal near the pedals.
a number of people in a facebook group have reported doing this and a few years later have seen no signs of failure. reportedly california ebikes has done one of these conversions as well. so purportedly the frame can handle it?

i am obviously hesitant to attempt this.

View attachment 351961

That's a lot of frame cutting . . .
A Cyclone mid-drive would have more frame clearance but takes more assembly.

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The recumbent version of this motor works swell.
Although it is handlebar throttle control only.

Otherwise it's a hub motor for your application.

 

[neptronix]

oh, sorry, i thought you were not recommending that build based on the comment "You have 10 minutes of this torture until it melts."

No, i'm recommending it, it will handle your most extreme grade for up to 10 minutes. I know your area, 20% grades don't last long.
Adding ferrofluid to the motor would be required to do this.

you also comment "it will take off like a rocket." what exactly does that mean? my kids might love the rocket like ride, but it seems a bit unsafe to me. Though i assume the throttle/peddle assist can be controlled to make the standing start more reasonable?

Yes, the same power level that allows you to take off like a rocket is *just barely enough* power to let you climb a 20% grade for, let's give it a safety buffer and say 5 minutes. With controller tuning, you could reduce the torque from a stall so that the bike isn't doing power wheelies, but still has tons of torque in the mid range ( the hill climbing power ).

Some controllers also have a up/down button on the screen for increasing and reducing the power level. This way, you can get out of programming the controller to reduce the overall torque, then increase the power level when you hit a hill.

One of the main reasons for choosing a hub motor is for regenerative braking. Going down a hill with a cargo bike with a ~300lbs load is a huge problem. A regenerative brake does not fade and lose power due to heat, it converts motion back into battery energy, which you need because these hills will consume tons of power. It also can be tuned to be stronger than the strongest disc brake, with a big enough motor.

You have a huge problem with the design of this bike. The rear doesn't look disc brake compatible. You don't want all your powerful braking on the front when descending a 20" hill. The bike will want to send you flying. What you actually need is the strongest rear brake you can get, a 203mm disc, but if the bike doesn't have a native connection for that, a disc adapter would be too weak to handle the force of such a large brake.

A quite high power hub would be the only safe way to get up a hill like this, and not die on the way down.

 

[gromike]

I agree with the choice powerful direct drive hub motor with regenerative braking for this trike. It's kind of a cheap trike from the perspective of sturdiness, and if you are carrying kids you need the safest, most reliable option.
You would need a low gear with a hub drive, but it looks like a front derailleur with two or three chainrings would be possible, and will get you some of taller gears.

 

[neptronix]

Yeah, the top speed of this configuration would be ~23mph, the motor would be doing 11-15mph up hill.

You can get rear cassettes with huge spreads these days, shouldn't be a problem to get the right bike gearing.

 

[ebike4healthandfitness]

Yeah, the top speed of this configuration would be ~23mph, the motor would be doing 11-15mph up hill.

You mean this example?

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...

endless-sphere.com

When I change weight to 330 lbs (from 220 lbs) I only get 9.6 mph. That is not too fast considering she has also to put 200 watts pedaling it into it as well.

Then remember she said wants to be able to get up the hills with her kids for "a long time to come" and her two kids were 60 lbs today but growing. That means she telling you to anticipate and plan for the children's weight increase. Young Kids grow fast!

So how is this motor going to be adequate for growing kids for "a long time to come"? This especially with San Francisco being a windy city. As I mentioned headwinds can really put the hurt on both legs and motor.

 

[ebike4healthandfitness]

You can get rear cassettes with huge spreads these days, shouldn't be a problem to get the right bike gearing.

View attachment 351995

And how much are 10 speed shifters, rear derailleur, cassette, chain, shift cable and other adapters like derailleur hanger for horizontal dropouts going to add to the bill. This plus installation costs.

 

[neptronix]

You mean this example?

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...

endless-sphere.com

When I change weight to 330 lbs (from 220 lbs) I only get 9.6 mph.

Yes, but if the hill is quite short, you still make it, even though the motor is bogged down to hell.
Switch to an 18" wheel for a little more torque in this high weight scenario, add ferrofluid, and you have 4.7 minutes till overheat.

Then remember she said wants to be able to get up the hills with her kids for "a long time to come" and her two kids were 60 lbs today but growing. That means she telling you to anticipate and plan for the children's weight increase. Young Kids grow fast!

60lbs combined or each?
The bike can't hold very big kids, i don't think this weight scales up much.

This especially with San Francisco being a windy city. As I mentioned headwinds can really put the hurt on both legs and motor.

Wind at 15mph is the least of your worries, gravity is your main problem - that's responsible for 1400W of the 1700W load while climbing a 20% grade with a ton of weight.

The only way I see it being adequate is if she adds a mid drive to help the RH212 get up to speed. Still do we even know if this trike will be able to use a cassette? Or even a mid drive?

Cassette interfaces on hub motors are not known for their strength, so we wouldn't want a very powerful one. It would be very helpful to increase the motor efficiency, but i think we're well over this virtual $1000 limit of we did that.

 

[ebike4healthandfitness]

Hub motor used a mid drive would be extremely p

the mid drive (bafang bbs02) will fit if you cut away some of the metal near the pedals.
a number of people in a facebook group have reported doing this and a few years later have seen no signs of failure. reportedly california ebikes has done one of these conversions as well. so purportedly the frame can handle it?

i am obviously hesitant to attempt this.

View attachment 351961

If you have this hub:

Shimano has a new version of Nexus 3 speed IGH that the company claims is stronger

These changes so far listed only on version B of the roller brake version of the Nexus 3 speed: https://bike.shimano.com/en-US/product/component/nexus-inter3/SG-3R75-B.html Claim by Shimano is the drive is 2.0 and 1.5 times stronger. This in addition to more stable shifting and better sealing...

endless-sphere.com

I would strongly consider the Bafang mid drive installation from California ebikes as one of your options.

P.S. Remember when using the ebikes.ca motor simulator that that hub has two lower gears in addition to the top (i.e. 3rd) gear which is 1:1.

So when plugging in the rear cog into the simulator just make sure you account for the lower gearing by making the cog larger than it is in reality when simulating the performance of 1st and 2nd gear. For third gear performance just use whatever the actual size of your rear cog is.

 

[999zip999]

Here's a picture of these torque arms that I want to use the steel one with the open bottom I cut that and I want to weld it onto an old giant upland frame for disc brakes.
I still agree that you should use of a thing mid drive and I guess you got a grind down that bumb. What's that bump there for anyways ?

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[Hillhater]

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

Unless i am reading that chart wrong, ..those results are for a TOTAL load of 100kg ?
I thought the op was talking of a cargo bike with a adult rider, (175 lb) and 2 growing (60+lb) child passengers ?
The bike itself weighs 30 kg and a motor + battery is likely another 10 kg
Even not allowing for carrying any other extras, .clothing, drinks shopping, etc.., that 100 kg is way off the mark, and will lead to a very different hill climing performance.
OK, ..so i see now you re- ran the sim with 150 kg,…much more realistic !
But <5min to overheat ?……thats risky if more than one hill to tackle !

 

[neptronix]

Scroll up a couple posts and see the revision of my suggestion