Dumb question: why are there e-power cutoff brakes at all?

[richj8990]

Never used them, threw them in the trash when I got the hub motor kit. Never had to use them, because if I did throttle and wanted to slow down, I lifted off the throttle. If I did PAS, I quit pedaling. Put on hydraulic brakes instead and never looked back. The only time I 'could' have ever used them is when I was in cruise control on a KT controller and had to look down and put the PAS to 0 when I wanted to slow down. That's the only time I would have needed to use brakes with e-power cutoff. PAS and throttle on/off (usually) do a great job of starting and stopping the motor by themselves...no need for redundant brake cutoff of power.

However...I plan on trying out a mid-drive w/o a front freewheel, as in it's a fixed chainring that automatically moves the pedals when in PAS 1-9. Dangerous? We'll find out won't we. We'll also see how hard I can freeze the pedals in PAS mode to stop them and provide a signal to the controller to cut power. This is an experiment --- that may very well fail later. Will choose nice open spaces to do this in lol. If freezing the pedals in place with my shoes to stop the power doesn't work w/PAS, then throttle off would send a signal to cut power when not using the throttle. So I'd just throttle around instead and not use PAS.

3rd safety net: there are now decent-priced hydraulic brakes that have 3-pin wires to connect with an extender group of wires that then goes to the controller. The real question is: if in PAS mode, and I can't stomp on the pedals enough to stop them in a fixed position so the PAS sensor reads 'stop' (remember no front freewheel), will braking send a signal that overrides the power signal constantly coming from the controller. If yes, I don't even need to press hard on the pedals, I just tap the brakes. Easy. Same with using the throttle if it gets stuck on for some reason.

Will all three of these above methods override the power signal from the controller to the motor, or is there a power cutoff pecking order that a typical controller prefers (KT ones).

 

[lnanek]

Personally, I get much better starts at traffic lights if I keep my throttle fully cranked and just barely pull my e-power cutoff brakes enough to cut the engine until the light turns green. PAS is no good for this since turning the gears from a stop takes effort, and twisting the throttle fresh to start isn't as good. Laggy and not strong at all due to throttle ramping settings and sometimes the controller thinks the wheel isn't moving soon enough so falls back to sensorsless start, which is way worse.

 

[ccihon]

I have heard many folks choosing to do away with brake cutoff circuits, both for hub and mid-drive setups. I do think in normal use, most people have already initiated a "power-off" by stopping pedaling or releasing the throttle before using the brake levers. I have heard a few stories where others use the cutoffs to kill power directly to shift, etc.

Regardless, these may provide a fail-safe against a runaway motor, and do so intuitively (stop means stop). You situation may require something like that.

Finally, the cut-offs can also function to signal motor off or "brake-on" for other purposes, like active brake lights, or indicating brake on to a controller capable of regen or motor braking. Another situation they can prevent is accidentally throttling a bike while standing still

I am using mechanical disks, and have magnetic switch sensors on the levers. I might install a hydraulic set, and look for levers pre-wired for cutoff, as the design of the hydro levers often seems to make the pivot point hard to use as a magnetic attachment point that separates cleanly from the sensor. Hydro levers with pre-installed cutoff switches limit the lever choices quite a bit, so I may do without the cutoffs

 

[E-HP]

They are faster to reach than the power button if you have a throttle related ground fault.

 

[ZeroEm]

The question: why are there e-power cutoff brakes at all?
The answer: not everyone has their ebike skills as finely honed as the folks on ES. When they get shaken they will grab the brakes.

 

[Sturmey]

In Europe, there is also a requirement under EN15194 as quoted below. They may not be required with certain torque sensors as they may cut off the power quickly within 2 meters.

... assistance shall be cut off when the cyclist stops pedalling forward such that the cut off distance does not
exceed 5 m with the use of brake lever cut off switch or 2 m without the use of brake lever cut off switch.

 

[Adrian_]

I use brake cut off sensors for regen, I have an inline switch so I can turn them off if I want to. The cut off switches also saved my life once when salty snow got inside my throttle plug and shorted 5v throttle supply to throttle signal making the throttle stuck at max power which is scary when you're in traffic on a 12kW bike.

 

[999zip999]

I have mine on the left hand for region in the rear and front brake if I need more break I reach down a reach for my right hand rear brake you know I have rim brakes with cool stops. But my front rim brakes are XTR with a special lever in there.

 

[HillCruiser]

You don't need them until you REALLY need them; I went through the shorted throttle scenario as well.
My standard advice to beginning riders is if things start going awry, just pull in the brake.
(This applies to experienced rider as well)

 

[mcfizzlestag]

I hated running without brake sensors. With torque sensing, it's easy to put too much pressure on your pedals at a light, you end up causing the bike to try to take off. Sure hydraulic brakes can hold it, but it's unnecessary strain on parts.

With Regen braking, you save a ton on pad wear.

On my mid drive, I do not use the shift sensor, I just trigger a break lever like a clutch when shifting. This way I can keep pedalling. On a mid drive without the brake cut offs or brake sensor, no matter how well you baby it, you will here that horrible clunking of a loaded shift from time to time.

I personally use hydraulic brakes with build in cut offs. Originally got Shimano ones from em3ev, and upgraded the calipers. Now I have tektro Dorado brakes (4pot calipers) and loving them, only switched due to snapping a lever in a spill.

My wife's mid drive set up has the magnets and cut off sensors put on her hydraulic brakes. Epoxied the sensors on to the brake lever body, and used the hole on the magnets to fasten them with #4 screw + epoxy to the lever, eventually I'll paint them black to match the brakes so they are less noticeable

 

[Chalo]

The question: why are there e-power cutoff brakes at all?
The answer: not everyone has their ebike skills as finely honed as the folks on ES. When they get shaken they will grab the brakes.

And yet, this reasoning seems not to apply to any other motor vehicle that people use. Why single out electric bicycles alone?

I often see drivers go down the road with their brake lights on, because they're resting their left foot on the brake pedal all the time. Seems to me they could benefit from a brake activated power cutoff more than we can, but cars don't come that way.

 

[E-HP]

And yet, this reasoning seems not to apply to any other motor vehicle that people use. Why single out electric bicycles alone?

I think there'd be a lot or car crashes if drivers needed to press a button to disengage cruise control.

 

[lnanek]

I admit I often keep one foot lightly on the brake and one on the gas at all times in cars. I just find it silly the convention is to use one foot for both when that adds unreasonably large switching time moving your foot when you need to brake or start from a stop on a hill at a red light.

 

[DogDipstick]

And yet, this reasoning seems not to apply to any other motor vehicle that people use. Why single out electric bicycles alone?

~eems to me they could benefit from a brake activated power cutoff more than we can, but cars don't come that way.

Yes they do lol.

tell me you never built an engine controlling ECm and tuned it ( the 16x16 maps, or 32 x 32 maps)...

there are MANY OEM designed " cutofffs" implemented whn you hit the brake pedal and you , as a consumer, not a maker, just dont see it.

your car does many things when you hit the brake pedal you might not know about. Such as cutting off the pulse width of the injector on the map bbased on the flow of the air and the rpm of the ticking engine.

On the fuel map. On the igintion map. On the target tables . On the lookups. For sure. Unlocking a tork converter lockup is one. Stopping the cruise control is antother, ( enacted by the application of the BRK circuit) ( cuts "off" all and any power thr5ough the throttle circuit when the BRK is applied.. henceforth a " power cutoff" t6hat stops all forward motion of the cruise control... )... ... Many many many many.

EVERYTHING is fly by wire now.

Go try it. Check your fancy new car that is filled with electronics. Iknow that even a T1N 2004 Sprinter minivan will have CANBUS linked to the th sensor and will not allow any throttle application when the th is pressed ( OM642).. and shit that is 20 year old electronics. The engine WILL NOT REV when the BRK sensor is triggered... and if you cannot trigger ( that) BRK sensor.. you cannot even shift out of park. Or out of drive. ( ask me how I know)( doing it right now, trying to figure one out, mercedes shifter canbus controlling .. everything.. in 2004.. faults in teh amchines .. figuring faults in the machines is one thing I get paid for.. )



lol. Chalo. Never built a fuel controller from scratch?

 

[caleb7]

I sometimes use brake cutoff to disengage the PAS (generally not braking actually, just pulling lever enough to activate cutoff) and to pedal very slowly between tight spaces etc. Sometimes I stand on pedal by braking just to go very slow, brake cutoff is also good for that I think (however I don't know if that helps going slow). That's easier than pressing a button a few times next to the screen to turn off PAS for a few seconds.

I think that's good ebrake cutoff exist in case throttle gets stuck during a ride, to stop without damaging the motor. Probably I'd not feel good without ebrake with a 1.000W BBSHD. (I also have battery power switch in reach, but anyway...)

 

[Chalo]

there are MANY OEM designed " cutofffs" implemented whn you hit the brake pedal and you , as a consumer, not a maker, just dont see it.

your car does many things when you hit the brake pedal you might not know about. Such as cutting off the pulse width of the injector on the map bbased on the flow of the air and the rpm of the ticking engine.

I only ever owned carbureted cars and motorcycles. I don't care to rejoin the ranks of the sociopathic by owning another poison spewing death chariot.

What I notice is that even today's stinky gas cars and motorcycles don't stop running when the brake lights come on. That would be equivalent to what e-brake levers do. Show me one that does that, or my assertion stands.

 

[biphaeboh]

Auto stop start has been around for a while.

As the name implies, automatic stop/start shuts off the engine instead of it idling at a stop and then rapidly restarts the engine when you want to drive away. If you do a lot of stop-and-go driving, you're reducing emissions and saving fuel by not idling for extended periods. More important to the automakers, adding stop/start tech increases Corporate Average Fuel Economy (CAFE) figures, helping offset all those big SUVs being sold.

What is auto stop/start? Autoweek explains

Fuel-saving stop/start tech is showing up everywhere; here's how it works

www.autoweek.com

 

[Chalo]

Auto stop start has been around for a while.

What is auto stop/start? Autoweek explains

Fuel-saving stop/start tech is showing up everywhere; here's how it works

www.autoweek.com

That's also not doing what power cutoff levers do. No ICE motor vehicle goes completely dead the instant you touch the brake. I guess 400hp, 5000lb vehicles are safe enough that they don't need to do that, but 1hp EVs are so wildly hazardous that they need to be completely shut down at the merest hint of brake lever movement.

 

[ZeroEm]

And yet, this reasoning seems not to apply to any other motor vehicle that people use. Why single out electric bicycles alone?

I often see drivers go down the road with their brake lights on, because they're resting their left foot on the brake pedal all the time. Seems to me they could benefit from a brake activated power cutoff more than we can, but cars don't come that way.

Seen people smoking the brakes from riding them. In the old days some used to ware out throw out bearings from riding the clutch.