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Forum CLOSED as of now

Mon, 25 Oct 2021 11:39:51 +0200

As announced to most active members, this forum is now closed - rather view-only from now on.
I'm very sorry to have being forced to take this action. Spam filtering was just taking too much time.
All posts are still there for archive reasons.
Don't forget there is a FaceBook page where you can post, connect and shout out.

Test, just a test

Thu, 03 Jun 2021 11:14:43 +0200

Hello. And Bye.

Automatic vs. manual

Thu, 14 Jan 2021 22:12:03 +0100

Instead of the self-made buzzer/button unit, I would like to use the TranzX AGT unit which is available here:

This Unit has 3 buttons: "-" and "+" for manual shifting, "A" for automatic. And a small LED display for the selected gear.
Looks perfect for this project - though I do not know how it is wired.

A similar item from the same vendor is 50% more expensive and has a different connector:

What do you think?

Found a video from TranzX AGT (automatic gear transmission):

variable travel of cable from servo to gears

Mon, 05 Oct 2020 17:05:41 +0200

For anyone who may be interested in having the cable travel adjustable, I'll share this idea...
Say you're using a 15mm servo horn, but don't all gears covered? You can use a larger diameter and try it out of course.
In the process of developing Shift4Me, I thought about an adjustable travel of the cable, with the same servo horn.
Here's what I came up with: a piece that would turn around a fixed point of the bike, and with cable fix points that could be adjusted along the piece. That way, you could adjust the amount of travel without disassembling anything.
I never tried it out (because I loved to keep a minimal design) but it should work.
Possible disadvantage: a little tolerance in the travel caused by the pivot point of the piece.

servo-coupling.jpg (Size: 15.32 KB / Downloads: 23)

Ultegra 6800

Sun, 04 Oct 2020 13:26:09 +0200

Has anyone tried it with an Ultegra 6800 RD ? I have tried a PowerHD 20Kg servo (6.6V), however it’s only able to pull one gear from the lowest gear. Horn radius is 15mm.

Why no friction unit?!

Tue, 29 Sep 2020 02:53:16 +0200

Or am I missing it from your build files?

Friction of gears is not anywhere close to keeping the cable from overcoming it and servo has to maintain a constant current draw just to keep it in place! Small wonder you only get a few hours of runtime... I've tested that personally with a wattmeter, and I am using a 35kg servo!

I'm using a similar principle electronic shifting for quite some time, using a nodemcu with a modified motor shield, 2s lipo battery, and a 3d printed housing just for the servo - the shield with a box "lives" in a frame bag.

I also have a blynk "module" to setup shifting servo angles wirelessly, but I reflash it with wifi off because it drains a ton of power.

I also has 3d printed shifting buttons, but frankly the I'll need to redesign it...

My main goal was not automatic shifting actually, but management of 3 cassete clusters in one transmission - on a recumbent bike that is supposed to be faired and require wide range AND small steps between gears... but I've simplified the design to just two cassettes and it turns out manual shifting of 72 speeds is not confusing at all actually
Still, it can be quite useful for an automatic electric transmission that can provide lots of torque at high efficiency AND at wide range of speeds.

Btw, have you thought about torque-sensing BB integration? It will be better than just cadence! Interfaces with arduino neatly and costs just 65$ -though I've yet to play with it, to busy finalizing my bike frame.

I'll share the design files once I brush them up a bit...

account activation

Wed, 09 Sep 2020 11:38:10 +0200

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Idea for better shifting

Tue, 08 Sep 2020 17:54:33 +0200

A fellow auto shifter enthusiast here. Been having a nosy at your code, very impressed. I can tell it’s been developed over some time and had considerable thought put into it.
I'm too addicted to my enviolo (NuVinci) hubs to want to build one and don't really like derailleur gears. Therefore the following is just a suggestion and not able to test it myself.

I noticed in the code and could hear in the video that the servo only moves to the next gear position. Mechanical shift levers have a tendency to move the derailleur past the next sprocket and then drop back to the next position. Think its only when shifting to an easier gear but it helps with quicker shifting.

My suggestion is that this could be programmed in so that the servo does to same thing. Slightly over shift and then drop back, not sure for how long or by how much. Something to test if you want or perhaps the shifting is fine and this isn’t needed.

Also just remembered something else that has almost made me build a derailleur auto shifter just to test it and that is.

Time the shifts to happen at the dead spot of the pedal stroke.
As far a I know this isn’t implemented on any electronic shifting due to the need for a cadence sensor. However you have a reed switch for cadence measurement so the position and timing of the crank is known.
Would love to know if it could remove the need to ease off the power when shifting.

you don't understand what "open source" means

Sun, 06 Sep 2020 05:08:44 +0200

Open source does not mean "I put some files up for download." Open source does not mean "I force people to register in my forums to see the files."

Go read the wikipedia definition for open source.

Pick a license, and then put your stuff up on github like everyone else. Nobody's gonna sign up for your web forum.

And a heads up to anyone thinking of doing so: there are no "source" files except for the arduino. Just PDFs of an incredibly rudimentary circuit layout, STLs for some very basic 3d prints, some build instructions that leave out a bunch of information (like why there are several servo horn mounts)...

longer battery life with other servo

Sun, 30 Aug 2020 13:55:20 +0200

As said before in this thread, the switching from the recommended HD-1501MG to the LF-20MG servo (both from PowerHD) is a big improvement.
Here a some figures, after riding it a couple of times until the battery was drained:
With the LF-20MG, the first "battery-low" flashing LED warning was after 240 kilometers. Then after 280 kms, it flashed after every gear change. After 305 kms, the battery was completely drained and the servo wasn't able to pull the cable any longer.
To compare it to the HD-1501MG: first battery-low sign after 80 kms, battery drained after 110 kms or so.
As far as I can tell, the little extra cost of the LF-20MG is worth every cent!

Downloads, documentation and code now on Github

Wed, 26 Aug 2020 11:36:33 +0200

Hi there,

I created a github repository and uploaded all documentation and installation files here:

https://github.com/vanvuongngo/Shift4Me

Feel free to create new "Pull requests", issues and comments.

best regards
asialife

intelligent-drivetrain

Tue, 25 Aug 2020 18:55:03 +0200

Hi Jan

Very nice implementation.
Thanks for making it open source!

Now that it is "stable" please have a look at:
www.rideshimano.com/global/en/Shimano-Di2-the-intelligent-drivetrain/

Regards

Improvements

Tue, 25 Aug 2020 15:41:46 +0200

Just add a speed sensor - reed contact and a magnet - to the setup to detect if the bike is moving. This could be used to detect downhill without pedalling or rolling towards a traffic light or standing... Would be only a few lines of code. Store actual speed, compare newe speed. Speed same or increased -> downhill, same or lower -> rolling towards a light. No crank, no speed -> standing.
Also, possibly decouple servo and actual pull at the bowden. Servos don't like constant pressure pull.

Modified power management (LiOn instead of NiMH)

Tue, 25 Aug 2020 15:31:52 +0200

Hi Jan,

very interesting project I found today in the German "Heise-online" article and congratulations for this great idea and the complete instructionss and more...

Since I´m also doing some Arduino programming and 3D printing I have read everything to understand in detail what is done here. :-)
Currently I do not have abike but waiting for my dream bike is back in production. Seems that a lot of parts from China are missing and production in Germany is on hold.

However I developed an Arduino Mini based anti-thief alarm circuit with 105dB sirene based on a acceleration sensor.

And here comes my idea for an improvement of your electronic design. I used a LiOn single cell 18650 (3450mA), a DC StepUp converter (3A) and a LiOn charge / protect module.

The cell has a an output of 3.7 - 4.2V nominale and can be discharged until 2.9 safely. The output voltage can be adjusted via the DC Buck-converter to 6V for the Arduino and servo. So there is no need for 2 batteries. Additionlly I would not use NiMH cells due there is still a little memory effect but also I would say that your charging concept with 2 cells packets in row with different voltages and different discharge current is not very healthy for them. All cells placed in row should have the same dischrage level before charging them.

Here I have attached some links to cells and the modules. maybe you think about this for a future design.

https://www.conrad.de/de/p/samsung-inr18...99572.html

https://www.amazon.de/Lademodul-Schutz-A...B07FB6PLKM

https://www.amazon.de/LAOMAO-Step-up-Con...MDQQ6DHNE8

https://www.conrad.de/de/p/panasonic-ncr...36402.html

button behaviour

Thu, 20 Aug 2020 11:49:08 +0200

Hi. When I push the button and release it after the first beep, that puts it in bypass mode, am I right?
What I was wondering: when I'm in this mode and I push the button again, I don't hear it beep. Is this normal behaviour?