View Full Version : Cut throttle when brake active?

24 August 2014, 1521

I have a Magura throttle which i misstake do not realy works well. I see that potentiometer do not work linearly, it raises, but after short movement it going lower and after this point value rises again. I have a knee in the begining. So it can be challenging to drive slowly.

Thanks to this i had a very unpleasant experience few weeks ago, when i was making a sharp left U turn on my parking space. My goal was to slowly turn around so i could park with my rear to power outlet, when suddenly bike accelerates very quickly and i hit a wall with my front tyre at 8-9 km/h. Since i was turning left it was difficult for me to release throttle, i think i am locked it in position by my hand. I tryed to activate rear brake but it was to late and braking force was to low.

I have a kill switch i can activate with my thumb, but it was too short time to react ( and distance was 2-3 m) and activate it. So now my hands are hurt a lot thanks to they take all my weight when bike crashed to a wall. I am lucky when i do not get a cracs in hand bone

So now for my question.

I will of couse change the throttle, but was thinking about if i can improve my circuit and prevent this failure in future. I am thinking if i can send 0 Ohm to controllerby short throttle signal when i apply hand or foot brake.
I have a alltrax, on this schematic i think i can short wires 2 and 3 in the throttle by using a relay which is active when brake light line is active.

Anyone who have some ideas if it is a good idea or see any problems with this setup?


24 August 2014, 1719
Sorry to hear about your accident. That can hurt. That being said, you sometimes want to use the brakes and the throttle at the same time. It can be helpful to use a dab of rear brake to tighten up a turn, when you don't wish to upset the balance of the bike by changing throttle. Or if you want to impress the lads at the pub, front brake + throttle = burnout. There are other situations, but as a motorcyclist I wouldn't want to make that change.

25 August 2014, 0336
I also thought initially to stop the throttle when braking but after a few tries I disabled this function. Now I realize how often I use the throttle and brake at same time.

Ken Will
25 August 2014, 0610
Some people connect the power disable to what was the clutch lever.
They say it seems natural.

25 August 2014, 0703
For racing, I've found that connecting the front brake switch to the controller's inputs was pretty handy, provided the rear brake was not connected. IF you are ever going to need some brakes while holding a constant throttle, the rear is probably the better one to dab. The only time a front brake needs to be on while the throttle is open is when doing a burnout. Which is cool, but I don't do burnouts that often...

I should add that I have a small reed relay which is activated when the front brake is touched. The contacts of the relay then complete a circuit from the brake signal output of the controller to ground.

25 August 2014, 1734
Most controller have a dual analog input , one is for throttle potentiometer , the second is for brake protentiometer , of course when you have the brake potentiometer the throttle is disabled.

This is good on cars or other vehicles that can have a good energy harvesting from regen , so the controller try to follow the brake request with more and more regen.

on Motorbike the story is a little different and first you have 2 separate brake system (front and rear) second using brake and throttle in the same time is more common (stil a bad thing to do on leectric because you are wasting energy but anyway) , on motorbike you can have a good improvement on throttle reliability using both channel and a dual potentiometer , in this case the analog inputs need to be configured as throttle 1 and throttle 2 , the controller will take care to compare the inputs and filter out wrong command from a worn out potentiometer. Also will stop the bike if the two potentiometer are not working correctly. On ICE racing bike sometimes you have a 4 channel throttle potentiometer for better precision and reliability.

26 August 2014, 0816
Thank you all for your responce. I can always try the circuit and it should not be hard to disconnect it if i do not like it.

Is there is any throttles with dual potentiometers? Becouse Magura have single potentiometer.

By the way do anyone know maximum voltage for Maguras potentiometer, i use it with 75 V system and can not find this kind of information on their website.

26 August 2014, 0932
Magura is a 5k pot, the controller will determine the voltage. It's usually 5V. The throttle should be connected to the controller throttle input, which is independent of the battery voltage.

I would say try a new throttle. Sounds like you just have a bad potentiometer, not uncommon with Maguras.