PaulD's lightweight mid drive development

ScooterMan101 said:
What Bottom Bracket / Crankset ( Make and model )
is that BB Cadence Sensor made for ?
Sram makes it to be e-bike capable ( heavier than the XX1/Xo1/GX Kits )
and very important somewhat affordable price of $ 380 for the entire drive train ( Shifter/Derailleur/Crankset/Cassette 11-50t /Chain ) except for the BB since there are many different BB shells on bikes these days.
Click to expand...
The Sempu torque/cadence sensor is made for square taper cranks. It looks like ISIS or other spindles for the newest T4 sensors would be a custom development project. Square taper cranks are fine for road/gravel use, and for about 90% of mountain bikers. But there's that 10 or so percent of MTB riders that are too aggressive for a 15mm spindle.
I intend to supply my kits with Shimano STEPS cranks that have a very low offset for low Q factor.
Regarding the Sram parts, yes, there are some great options for ebike 1X drivetrains these days.
 
Drum said:
Talking about a system with no crank freewheel, in many ways I find the thought a bit scary, but on a bike without a throttle and with a relatively low powered motor it should be possible.
I recently rode a bike with a "backpedal brake" (coaster brake) version of the Tongsheng TSDZ2 motor which has this setup: the chainring is bolted to a large output gear that is directly driven by the pedals (through the torque sensor) AND by the motor (through a freewheel). The only thing causing the motor to run is output from the torque sensor.
When I pedalled hard, then stopped suddenly, I could feel the pedals kick forward briefly as there was a minor delay in the sensor / controller dropping output to zero, but though it was noticeable it was not dangerous and I quickly got used to it.
I would prefer a crank freewheel, but as long as the sensor and controller combination could be set up to drop output to zero very quickly, it could be worth a try.
Click to expand...
Yup, totally agree. A freewheel is a must. I attempted to wheelie drop a curb the other day, and was suddenly reminded that I can't ratchet the pedals back quickly with the drag of the motor!
Having the motor immediately apply regen when sensor output goes to zero solves the tug at the cranks issue (Justin's had this idea last time we spoke), but it doesn't solve the above issue with backpedalling.
 
How did i miss this awesome thread? :oops:

Looking forward to seeing your build up and running!
 
This is the development that I've been awaiting. No sense having a 10 pound BBS02 when my wife and I use level "0" or "1" (of "5") 99% of the time. Thought one of the major manufacturers would develop something, but they're too busy playing the "me too" game.
 
It seems I also missed this thread the first time around. I really like what you're doing PaulD. I'm very impressed with your overall design and the execution of your individual components.
 
Put me in the small category of people who have no use for anything over 350 watts. I have the 36 volt TZDS2 and it has just the right amount of power to make me feel young again. I stay in the middle two levels and feel like I used to at my peak fitness 20 years ago. I have dirt bikes if I feel the need for speed.

Let everyone else slug it out in the high power market, stay focused on weight reduction and low cell count.

Can you replace the 25 chain with a quieter toothed belt?
 
hobbyvac said:
Put me in the small category of people who have no use for anything over 350 watts. I have the 36 volt TZDS2 and it has just the right amount of power to make me feel young again. I stay in the middle two levels and feel like I used to at my peak fitness 20 years ago. I have dirt bikes if I feel the need for speed.

Let everyone else slug it out in the high power market, stay focused on weight reduction and low cell count.
Click to expand...
Not intending to detract from this thread, but i assume you are aware of Keplers drive package ?
...they dont come much lighter, stealthier, or simpler ...if that is your need.
 
Thanks for the encouragement, guys. Great to hear that there is interest in modest power levels, smaller batteries and light bikes.

hobbyvac said:
Can you replace the 25 chain with a quieter toothed belt?
Click to expand...

It's possible. Clearance is tight, and a chain is (generally) narrower for a given power level than a belt. I have this on my to-do list to research more once I have beta motors up and running. Motor housings should arrive today!
 
Hillhater said:
Not intending to detract from this thread, but i assume you are aware of Keplers drive package ?
...they dont come much lighter, stealthier, or simpler ...if that is your need.
Click to expand...

I like Keplers friction drive, really clean design. The advantages and disadvantages of mid-drives and friction drives are pretty well understood and have been discussed a lot on ES.
 
Once again, I've neglected this thread since I've had my nose to the grindstone lately. I think gravel adventure/exploration bikes are a great application for ebikes. Here's a Salsa Fargo we converted. Ended up pretty light (i'll weigh it sometime soon), with lots of space left for bags, tools and water.
Fargo gravel road RHS.png
 
Another quick update. The 100mm Sempu T4 torque sensor allows us to install this kit (with a few extra spacers) onto a fatbike with 4.7" tires. Looking forward to winter, or a trip to the coast!
View attachment 2
fatbike2.png
fatbike3.png
Also, I am looking for Beta testers for the kit. We have a few Beta prototype kits that are unaccounted for at this time, so please PM me if you are interested. Testers need to be within driving distances of Ashland, OR and have a bike they would like to convert.
 
Subscribed! I am a builder/developer in the oh-so-tiny off-road handcycling scene. E-assist has proven to be a game-changer. However, most of the DIY kits don't integrate too well into the available equipment. This kit looks like it has fantastic potential.
 
ions82 said:
Subscribed! I am a builder/developer in the oh-so-tiny off-road handcycling scene. E-assist has proven to be a game-changer. However, most of the DIY kits don't integrate too well into the available equipment. This kit looks like it has fantastic potential.
Click to expand...

Thanks ions. We are making good progress, and ironing out issues before we begin building production units. We are working with Egg Bikes to develop custom firmware for their rad little display to work with our ASI BAC-500 controller. It seems like gigantic color displays are popular these days, but I prefer the minimalist approach.

egg display on yuba.png
 
I was gonna suggest hacking the eggrider for a minimalist display that matches the minimalist mid drive.
GJ on that.
 
Anyone else interested in "crowdfunding" this project? It keeps getting better with every update. As e-bikes grow in popularity, I think the small/stealth/unobtrusive systems will develop a strong following. While there will always be the bigger=better crowd, many people just want to enjoy exploring the world. Shredding up drivetrains and ripping through traffic at 35 mph isn't what a lot of people have in mind. 350W can be enough to take you anywhere you want to go.
 
If he wants to crowdfund it he's free to pimp the kickstarter on the endless sphere facebook page once since this is a cottage industry type thing.

..and a cool product.

..or hell, i'll pimp it myself
 
Thanks guys! We are good on funding for a while, our main constraint is time. In fact, I am hoping to hire or contract the help of an electrical engineer soon. I am pretty slammed, and have a young one at home, so it's tough to keep things going at the pace that I'd like. Perhaps I'll post a job listing. There seem to be quite a few qualified folks on ES.

I think a kickstarter might be a good way to spread the word. I've spent very little time and $0 on marketing, and it would be nice to keep it that way, and put those resources into development and testing. Using KS as a significant funding source usually doesn't go well (there are exceptions).
 
Kickstarter should be a good way to get your idea/design/product , visible to Hundreds of Thousands to Millions of People.
Now that I know of the Kit Price of your mid-drive which sadly it is over my budget . ( I am on a Fixed , Low very Low , Retirement , Income. )
However
There are many people in the world where your price point is doable, and Kickstarter will reach enough people to pull in those customers and make your business successful .





PaulD said:
I think a kickstarter might be a good way to spread the word. I've spent very little time and $0 on marketing, and it would be nice to keep it that way, and put those resources into development and testing. Using KS as a significant funding source usually doesn't go well (there are exceptions).
Click to expand...
 
Marketing is unfortunately key with these things.
Things have succeeded on kickstarter that shouldn't have in the past, just because of good marketing.
And i've seen legitimately good things fail on KS due to lack of marketing.

I'd outsource that task to someone who is capable.... but don't ignore it.
 
micah78 said:
I will follow this post and buy it when it's ready.
Click to expand...

Thanks Micah, it's looking like January-February is our new target. Beta testing is process, and we have had some delays on our battery potting equipment and other bits that have pushed things later. It's the nature of product development!
 
Thanks for checking in! The motors are slowly nearing availability. Beta testing has been very successful with only minor issues, but procurement of production parts has been a challenge. The final bits and pieces (custom freewheels for the sempu T4 bb) are actually arriving next week, so I should have motor kits available very soon. Batteries are good to go, with UN testing complete and class 9 shipping packaging ready. Custom firmware for the Egg display is finally fully functional. So many little things to bring it all together! I'll try to write a more detailed post soon!
 
Paul,

I see on you have installed this motor on about 6 or so bikes ... all of which have straight down tubes .
( Straight from the head tube all the way down to the BB shell of the frame )

Many people have full suspension bikes that have what is called a dog leg , down at the BB area of the down tube.

What plans do you have to make available the two mounting brackets several inches longer and then a upwards curve
where the motor will be next to the down tube ?
 
ScooterMan101 said:
What plans do you have to make available the two mounting brackets several inches longer and then a upwards curve
where the motor will be next to the down tube ?
Click to expand...

We have installed kits on a Yuba cargo bike and transition scout that have swoopy down tubes. We have 2 plate size options. The longer ones tilt the motor and controller for more clearance. I'll have printable templates soon so you can test fit
 
You must log in or register to reply here.

Similar threads

R
    • Like
L-Faster / Dome Motor 450W Mid-Drive Build
2
Replies
25
Views
3,069
DanGT86
DanGT86
C
Chimera”... Antique style E bike build, circa 1915...why and how
Replies
6
Views
926
classicalgas
C
R
    • Like
A critique of mid-drive riding recommendations (and hub drive criticisms)
Replies
15
Views
5,059
Bullfrog
B
R
Mid-drive PAS with stuck or non-existent freewheel/clutch gear
Replies
8
Views
869
richj8990
R
R
Dual chain/drive lightweight mid drive - advice needed.
Replies
1
Views
287
flat tire
F
Back
Top