Adding a Rotary Dial Speed Control

6zfshdb

Well-Known Member
Region
USA
City
Northeast Pennsylvania
I occasionally get a cramp in my right hand when using my half grip twist throttle. As a remedy, I built this small control box as an alternate way to adjust speed. In doing some research, I discovered a 3 wire hall effect throttle can be emulated with a variable resistor. I wired the control box as shown:

P1090293e.jpg
IMG_1099b.jpg
IMG_1100b.jpg


I mounted the box on the left side near the display so it can be operated without taking my hands off the bars. It could be mounted almost anywhere however:

IMG_1102b.jpg


I used a triple pole double throw switch with a center off position. That way, I can change between the OEM throttle operation and the rotary control. The center position is off. The brake motor cut off and PAS systems are unaffected.

The 3 wire hall effect throttle is fairly standard in the industry and this idea should work on many different bikes.

Some soldering skills are required for the project since it requires cutting & splicing the throttle cable. The parts are all readily available from Amazon and I can provide a list if anyone is interested.
 
Last edited:

6zfshdb

Well-Known Member
Region
USA
City
Northeast Pennsylvania
Interesting.
I assume you are using it like a cruise control?
In a way, yes. I mostly use it to set an appropriate speed for where I'm riding and then apply whatever pedal pressure I feel like contributing. It's like a reverse PAS where I assist the bike rather than it assisting me.
 

JES2020

Well-Known Member
In a way, yes. I mostly use it to set an appropriate speed for where I'm riding and then apply whatever pedal pressure I feel like contributing. It's like a reverse PAS where I assist the bike rather than it assisting me.
How does that differ from just turning down the PAS?
 

6zfshdb

Well-Known Member
Region
USA
City
Northeast Pennsylvania
How does that differ from just turning down the PAS?
Performance wise, the two methods are quite similar. The main difference with using the PAS is, it's less efficient. The PAS system reacts to changes in pedal pressure which cause current spikes. With PAS, when you pause pedaling and resume again or change the amount of pedal pressure, there is a current spike. These spikes waste energy. With the pedal assisted cruise control, when you pause & resume pedaling, the current remains constant. By comparison, I get 14% more range using the pedal assisted cruise control vs the PAS system alone. Of course these results will vary by rider and bike make & model.
 

JES2020

Well-Known Member
Performance wise, the two methods are quite similar. The main difference with using the PAS is, it's less efficient. The PAS system reacts to changes in pedal pressure which cause current spikes. With PAS, when you pause pedaling and resume again or change the amount of pedal pressure, there is a current spike. These spikes waste energy. With the pedal assisted cruise control, when you pause & resume pedaling, the current remains constant. By comparison, I get 14% more range using the pedal assisted cruise control vs the PAS system alone. Of course these results will vary by rider and bike make & model.
I see. That sound a lot like the cruise control that comes with my display/controller.
I assume you not have cruise control on your display?
 

6zfshdb

Well-Known Member
Region
USA
City
Northeast Pennsylvania
I see. That sound a lot like the cruise control that comes with my display/controller.
I assume you not have cruise control on your display?
No, my display is pretty basic. I looked into upgrading the controller / display with one that has cruise control but the cost of all the necessary components was to high.
My next bike will definitely have that feature.
 

George S.

Well-Known Member
I occasionally get a cramp in my right hand when using my half grip twist throttle. As a remedy, I built this small control box as an alternate way to adjust speed. I discovered a 3 wire hall effect throttle can be emulated with a variable resistor. I wired the control box as shown:

View attachment 102769 View attachment 102766 View attachment 102767


I mounted the box on the left side near the display so it can be operated without taking my hands off the bars. It could be mounted almost anywhere however:

View attachment 102768

I used a triple pole double throw switch with a center off position. That way, I can change between the OEM throttle operation and the rotary control. The center position is off. The brake motor cut off and PAS systems are unaffected.

The 3 wire hall effect throttle is fairly standard in the industry and this idea should work on many different bikes.

Some soldering skills are required for the project since it requires cutting & splicing the throttle cable. The parts are all readily available from Amazon and I can provide a list if anyone is interested.
One of the ebike suppliers has a bike with a throttle but if you are cruising for a few seconds and let go of the throttle, it maintains that speed. The Golden Motors a few years ago had a cruise that would engage at the speed you were going, but it jumped to a higher speed most of the time. Very frustrating. There was something like this on the market 5 years ago. I don't think my PAS is exactly where I want it, but it has reached the point where it seems to be good enough. This is pretty creative stuff. I'd settle for dialing in the speed with the throttle and then locking that speed down, but the cruise control buttons I had were not at all precise. This is just totally manual, which is fine. You could say this replaces any type of assist system, and it's obviously not much money for the parts. With PAS you are always hunting down the 'magic' settings and you are always dependent on some algorithm Plus these days the manufacturers are locking down the settings. I hope this is a budding trend! You could refine this, memory or whatever.
 

6zfshdb

Well-Known Member
Region
USA
City
Northeast Pennsylvania
One of the ebike suppliers has a bike with a throttle but if you are cruising for a few seconds and let go of the throttle, it maintains that speed. The Golden Motors a few years ago had a cruise that would engage at the speed you were going, but it jumped to a higher speed most of the time. Very frustrating. There was something like this on the market 5 years ago. I don't think my PAS is exactly where I want it, but it has reached the point where it seems to be good enough. This is pretty creative stuff. I'd settle for dialing in the speed with the throttle and then locking that speed down, but the cruise control buttons I had were not at all precise. This is just totally manual, which is fine. You could say this replaces any type of assist system, and it's obviously not much money for the parts. With PAS you are always hunting down the 'magic' settings and you are always dependent on some algorithm Plus these days the manufacturers are locking down the settings. I hope this is a budding trend! You could refine this, memory or whatever.
I've seen several cruise control schemes on various bikes. Some work better than others.

I sometimes use this device for holding a throttle position:


It's designed primarily for motorcycles but it works on almost any twist throttle. It's awkward and a bit ornery to set up but works well enough once in position.
 

JES2020

Well-Known Member
I've seen several cruise control schemes on various bikes. Some work better than others.

I sometimes use this device for holding a throttle position:


It's designed primarily for motorcycles but it works on almost any twist throttle. It's awkward and a bit ornery to set up but works well enough once in position.
What happens when you release the brakes without disengaging the cruise control? I assume the cruise kicks in again?
 

6zfshdb

Well-Known Member
Region
USA
City
Northeast Pennsylvania
What happens when you release the brakes without disengaging the cruise control? I assume the cruise kicks in again?
Yes, it's the only thing I don't like about the device. It could be an issue if you don't exercise care when using it. Fortunately, the controller on my bike doesn't allow sudden motor surges and the throttle comes back on gently. It doesn't cause the bike to leap forward. Instead you feel a gentle pull when the brake is first released. I can't say if that would be the case on every bike though.
 

harryS

Well-Known Member
A nice DIY soulution there. I've also noticed that power consumption must be more uniform under consistent throttle, just from watching the watts readout on my KT displays stop fluctuating, as they do under PAS.

The KT controllers, with certain displays, have the option where if you hold the throttle steady for more than a few (10?) seconds, the bike enters cruise mode. It requires a jumper wire to be set in the wiring harness.

For some reason, it's enabled on my wife's bike and I've not figured out why.
 

mclewis1

Well-Known Member
Region
Canada
City
Fredericton, NB
Nice bit of DIY ... I especially like the construction and schematic.

For those without DIY skills (and a CA3 for control) you can get a commercial pot based control from Grin - https://ebikes.ca/shop/electric-bicycle-parts/ca-accessories/ca3-aux-al.html
"5kOhm Auxilliary Input Pot for CA3 devices with CNC machined aluminum handlebar clamp for securing to 22mm (7/8") handlebars. Allows you to adjust any of the speed, power, current, or PAS levels on-the-fly while riding. Manufactured in Canada with IP67 waterproof potentiometer."

The most popular usage appears to be road bikers who want to dial in just the right amount of assist.
 

JES2020

Well-Known Member
A nice DIY soulution there. I've also noticed that power consumption must be more uniform under consistent throttle, just from watching the watts readout on my KT displays stop fluctuating, as they do under PAS.

The KT controllers, with certain displays, have the option where if you hold the throttle steady for more than a few (10?) seconds, the bike enters cruise mode. It requires a jumper wire to be set in the wiring harness.

For some reason, it's enabled on my wife's bike and I've not figured out why.
On most KTs you have to hold the down button when at the chosen speed (above 11 mph), to engage cruise, it will hold you're chosen speed, flat or changing elevations.
As a safety feature, it cuts out on brake application and if you apply power 5 mph or so, above the set speed for more than a few seconds.
 

JRA

Well-Known Member
Nice bit of DIY ... I especially like the construction and schematic.

For those without DIY skills (and a CA3 for control) you can get a commercial pot based control from Grin - https://ebikes.ca/shop/electric-bicycle-parts/ca-accessories/ca3-aux-al.html
"5kOhm Auxilliary Input Pot for CA3 devices with CNC machined aluminum handlebar clamp for securing to 22mm (7/8") handlebars. Allows you to adjust any of the speed, power, current, or PAS levels on-the-fly while riding. Manufactured in Canada with IP67 waterproof potentiometer."

The most popular usage appears to be road bikers who want to dial in just the right amount of assist.
On my Grin component front hub bikes with CA3 I have a three button unit I got from them mounted on my left brake hood via a Bobmount next to my regen momentary button. It allows me to set my watt output in 250w increments up to 1000w. I can set my amount of power, basically the cruise control being discussed, within those settings with my throttle by holding at the desired output/speed I want to travel for 2 seconds and releasing. I then am free to use whatever gear I need for the situation. I don't have brake cutouts but depressing the regen button, which is the first then I do anyway when wanting to slow down or blipping the throttle disengages the function.

I use no PAS and like the way this system works as it allows me to pedal at whatever amount of physical input and cadence I want with no interference from the motor. It just maintains its own output at a steady rate which also does a nice job of deleting any lag due to my sometimes lazy spin technique and in fact allows me to better work on it actually when I feel like concentrating on it.
 

6zfshdb

Well-Known Member
Region
USA
City
Northeast Pennsylvania
I use no PAS and like the way this system works as it allows me to pedal at whatever amount of physical input and cadence I want with no interference from the motor. It just maintains its own output at a steady rate which also does a nice job of deleting any lag due to my sometimes lazy spin technique and in fact allows me to better work on it actually when I feel like concentrating on it.
I agree. I also rarely use PAS since the cruise control, in effect, works like an infinitely variable PAS. Once I dial in my ideal speed & cadence for conditions, I simply switch it off when stopping or slowing for an obstacle. I then turn it on again without having to re-adjust the setting.
 
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JES2020

Well-Known Member
I agree. I also rarely use PAS since the cruise control, in effect, works like an infinitely variable PAS. Once I dial in my ideal speed & cadence for conditions, I simply switch it off when stopping or slowing for an obstacle. I then turn it on again without having to re-adjust the setting.
Between the 21 gears, the 5 PAS settings, ... that's 105 settings to choose from. I usually set PAS to 1 or 2 and just use the throttle to make up any cadence issues.
I think I have only used the cruise a handful of time on long empty stretches.