09-29-2020, 12:53 AM
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.
![[Image: AHan0VZh.jpg]](https://i.imgur.com/AHan0VZh.jpg)
I'll share the design files once I brush them up a bit...
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...