Mobility Trike Build With Coaster Brake

[Rassy]

At 80, I had decided not to do any more electric assist projects, but a little background will help explain why I am doing this one:

On Wednesday, August 28, a friend in Eugene that I had converted his tadpole pedal trike to electric assist using a BBS02, introduced me to a friend of his that wanted an electric assist trike. She is 40, Lives alone, doesn't drive, and has a Cerebral Palsy or similar type of affliction. Her hand control is such that she can not trust just having standard lever brakes, but does ride a 3-speed pedal trike with a coaster brake. Unfortunately her trike is at her parents home in another state and she wants to keep it there to use on her visits home.

So the broad specs for this project are an adult trike with a PAS drive and coaster brakes.

So with a lot of searching, etc. my friend and I determined all the parts and pieces we need to complete the project:

There are very few new or used trikes available with coaster brakes so with her approval we selected a new Schwinn Meridian one speed that comes with lever brakes.

https://www.walmart.com/ip/Schwinn-Meridian-Adult-Tricycle-26-inch-wheels-rear-storage-basket-Blue/5679542?comm-msg-vehicle=EMAIL&comm-msg-id=66f3a608-b3e1-4115-80c9-1d2d0be4a442

We will use a 3-speed coaster brake trike conversion hub from Staton-Inc.

http://www.staton-inc.com/store/index.php?p=product&id=84

A mid drive TSDZ2 BK that is their only drive that supports coaster brakes. It will have a VLDC5 display and torque PAS. It is 36V 350 Watts.

https://www.electrifybike.com/store/p25/TSDZ2-Coaster-Brake.html#/

And a 36V 10AH LiFeP04 battery.

https://www.ebay.com/itm/283526537018

All the above has been ordered at a shipped cost of $1,150. Her budget was $1000 to $2000, preferably closer to $1000. There will by about $50 worth of odds and ends.

The mid-drive and battery have already arrived. The trike and coaster brake conversion kit have been shipped and are expected in the next few days.

I plan to compete the project by next week end. I hope it will run without a speedometer for initial tests because once everything is here I am pretty sure I will need an extension cable, which is available in any length, which I won't know until the trike is assembled, and could delay the completion for a while.

Needless to say she is anxious to be able to ride as she currently gets about on the taxi type services such as Uber, etc. and wants the independence to run over to the grocery store, park, or the nearby trail system.

 

[stevecahill]

Look forward to seeing this build.

 

[Rassy]

Sorry about not keeping this thread up to date. I have some pictures on my camera and have never uploaded them (or any others) to my computer yet but should be able to do that and will do so.

Anyway, the project was successful, the trike was delivered to her several weeks ago and she loves it. Our mutual friend and I have gone on several rides with her, including yesterday when we took the longest ride so far, four hours including a lunch stop. We all had time limitations and it was obvious we would have to ride a little faster to complete our planned ride so we asked her if she was comfortable enough to move the assist level up one notch, which she did, and her smile as she pedaled along at 8 or 9 MPH answered the question. The torque PAS is working out great, and one of my rewards for doing this project was the chance to experience the torque PAS during my preliminary tests. I'm even thinking about putting a 48v TSDZ2 with a throttle on one of my trikes in place of the current Bafang BBS02.

The hardest part of the project was making a change of how the rear trike part of the Schwinn Meridian was attached to the front part. Normally the jackshaft on the trike has an extra long axle and the rear trike part is attached to the axle outside of the inner part that contains the brake and gearing. The three speed hub with coaster brake has an axle that is only long enough to fit a regular bicycle dropout and did fit the jackshaft area, with adjustment to washers and nuts as needed. So I changed the angle of the rear part of the trike, drilled a couple of holes in the jackshaft dropout flats, made a couple of short struts to make a solid triangular attachment, and all is good. This change raised the seat about an inch and also required two spacers to make the basket sit level. When I get the pictures posted this should all become clear.

 

[Michael B]

The torque PAS is working out great, and one of my rewards for doing this project was the chance to experience the torque PAS during my preliminary tests. I'm even thinking about putting a 48v TSDZ2 with a throttle on one of my trikes in place of the current Bafang BBS02.

Despite the oh so regular same old very vocal ones running the TSDZ2 down every chance they get, in certain applications, it is a very convenient easy to like setup.

If someone needs to absolutely beat on it, the TSDZ2 is the wrong option.
If someone doesn't ride well using the gears, the TSDZ2 is the wrong option.
For 'assist' smooth, natural, cycling pleasure it's a really good option.

 

[LeftieBiker]

There is another thread that notes how fragile Meridians are. If I understand you correctly, you ditched the stock wheels? That should solve the 'fragile drive' issue. The other one, IIRC, is the amount of flex in the frame from rear to front. If that seems to be an issue you can of course add a brace or two.

 

[stevecahill]

What size TSDZ2 mid Drive Central Motor Conversion ebike Kit,Torque Sensor did you put on the trike? 500 Watt?

TSDZ2]TSDZ2 mid Drive Central Motor Conversion ebike Kit

 

[stevecahill]

Did find some interesting links for this mid drive.

https://ebikechoices.com/tongsheng-tsdz2-review/

https://mobility4less.com/fat-tire-electric-tricycle-2/

How to change the firmware:
https://www.youtube.com/watch?v=nj8GxKHut3o

 

[ZeroEm]

My mother has a Meridian, the rear rims are light aluminum, have had to true them a couple of times to keep them in shape. I put a front

Bafang Mini Geared G3.

The drive system powers the left wheel. It has a hub with a washer tack welded to it. I'm unsure how much power this setup can handle thru the chain. It is a good setup for her but she does not ride much. The trike is 20 months old but only has a few hundred miles on it.

 

[Rassy]

To show detail the previous two pictures were taken when the trike was still upside down during assembly.

 

[Rassy]

I will try to answer a few comments and questions that have been posted above:

I ordered the Coaster Brake Hub with a 3 speed IGH because I did not know exactly how she would use it in practice. Turns out she can not shift on the fly and just uses low gear all the time. I am still glad that I put in a 3 speed instead of just a single speed since low gear gives more reduction then a single speed has. Always being in low gear also means she will not be torturing herself or the system when starting from a stop or climbing a small hill such as the one her driveway has. I told her to just pedal hard for the first test up her driveway, which she did, and just rode right up it. Not sure if she was in assist level 2 or 3 that time, but now she makes those decisions as she goes.

I did not replace the wheels that came on the Meridian. She is a light weight person and will not be pushing the trike to any limits. I expect the Meridian to hold up with just nominal maintenance.

There is a link in the first post above to the TSDZ2 BK that was used. The BK model is the only TSDZ2 that supports a coaster brake. It is available in a custom 48V model, but the standard one is a 36V 350W motor, which is what I used. She easily varies her speed by choosing different assist options and applying the desired pedal pressure. I have observed her riding along as slow as 4 MPH and as fast as 9 MPH. I don't think she has ever used the highest of the four assist options yet.

 

[SlowCo]

Nice trike!
How is it that she can't shift? Maybe a different shifter needed?

 

[Rassy]

How is it that she can't shift? Maybe a different shifter needed?

Yes, there are some out there that might work better for her, but running in low gear gives her more speed than she requires, depending on the PAS level she chooses. She has a hard time controlling her left hand and fingers and has to use her right hand to first grasp the left grip and also to release her left hand from the grip at the end of her ride. Being in low gear also means she is ready to take off from a stop or able to climb the small hills that she encounters without lugging her or the motor down. The BK model is not available with a throttle since the freewheel system used to allow a coaster brake also forces the pedals to spin when the motor runs and would thus be unsafe in throttle mode.