Are motor cut-off brakes legally required?

I'm converting a Giant Roam 2018 using a mid-drive kit, and the bike has Shimano Deore hydraulic brakes as standard.

 

The kit comes with the magnet-style motor cut-off sensors which attach to the handlebars, which I'd would prefer to not use since I've read they can be fiddly/unreliable. However I'm not sure if cut-off sensors are required by law?

 

If they are required, I'd prefer to swap the brakes for something like the Magura MT5e which have the sensor integrated. If it's not required, would I see much benefit in upgrading to a better Shimano set with more pistons and/or bigger rotors?

 

Thanks!

No

This is something I dont quite understand.

With my bike - mid drive, when i stop pedaling, i pull on my brakes and I stop as with a standard bike.

So are hub motors on the go all the time ?. Why does the brake need to cut power to the motor. Surely if you go to brake, the natural inclination is you're not going to be pedaling as well. And if its a thumb throttle thing, are these throttles not spring loaded, much like a motorbikes accelerator ?

This is something I dont quite understand.

With my bike - mid drive, when i stop pedaling, i pull on my brakes and I stop as with a standard bike.

So are hub motors on the go all the time ?. Why does the brake need to cut power to the motor. Surely if you go to brake, the natural inclination is you're not going to be pedaling as well. And if its a thumb throttle thing, are these throttles not spring loaded, much like a motorbikes accelerator ?

You don't need brake sensors if you don't have full acting throttle. They are there to stop the throttle.

You don't want learn how important they are in front of a truck when your bike did not stop at a T junction.

 

Many people have combined their own choice of brake caliper with the brake cutout function by mounting the sensor part in the right place and attaching a magnet to the lever using tape or glue.

 

Bigger disc and 4 pot calipers will always give more stopping power if your riding requires it.

I DO NOT KNOW ABOUT MID DRIVE MOTORS. However my hub drive will not cut out as soon as the pedaling stops but a few seconds later, touching the brakes with cut off sensors fitted cuts the motor Immediately!!

 

I have also repaired a wheel that was in a rta without brake sensors, spokes were ripped from the wheel rim destroying the wheel.

 

Think of the brake cut offs as emergency stops for the motor, if you dont fit one at least consider fitting a switch on the circuit just in case..

It's better to use a controller that reacts quickly to your pedalling or better still, change to a torque sensor. My cadence sensor kits all have the option of lcd only which is without brake sensors and without throttle. It saves £15 worth of unneeded components and the wiring is so much simpler and nicer too. The 4 to 1 julet cable is replaced with a 5 to 8 pin julet cable for the lcd.

You have a torque sensored mid-drive [mention=29547]AndyBike[/mention], but with my cadence sensored Bafang BBS01B mid-drive, reduction in power can be adjusted using "Stop delay" and "Stop decay" in firmware - set as shown below, these enable rapid stop of motor assistance when pedalling stops - saves brake pads and rims (I don't want to be fighting to stop my legally 250W rated motor delivering 648W in the midst of tricky traffic or offroad), makes my bike very controllable. But it can be tough on my knees if I'm pedalling very hard when the motor cuts power at 25km/h, so I've become used to avoiding doing that via repeatedly painful negative reinforcement.

 

https://edrivenet.com/bafang-programming/

 

Edited February 8, 20242 yr by guerney

I'm converting a Giant Roam 2018 using a mid-drive kit, and the bike has Shimano Deore hydraulic brakes as standard.

 

The kit comes with the magnet-style motor cut-off sensors which attach to the handlebars, which I'd would prefer to not use since I've read they can be fiddly/unreliable. However I'm not sure if cut-off sensors are required by law?

 

If they are required, I'd prefer to swap the brakes for something like the Magura MT5e which have the sensor integrated. If it's not required, would I see much benefit in upgrading to a better Shimano set with more pistons and/or bigger rotors?

 

Thanks!

Brake sensors are not legally required on any bike with any motor or any other parts; however, there is a European standard for electrically assisted pedal cycles in which there is a requirement that the power must cut within 2 meters of stop pedalling. If you ran somebody over, who jumped out on you, and your bike didn't meet that requirement, you might have to take the blame, even if it wasn't your fault. The chance of that isn't very high because firstly somebody would have to jump out on you (low chance), you'd have to not stop (pretty low chance), somebody would have to know about the regulation (very low chance), and they'd have to test your bike (low chance). The overall chance of all those things happening is pretty close to zero.

 

Brake sensors are more or less essential when you have a crappy controller that runs on for 2 secs after you stop pedalling. They're also useful, but not essential for when you want to keep pedalling but slow down, like when you need to keep pedalling to shift down your derailleur gears as you come to a stop.

Edited February 8, 20242 yr by saneagle

Thanks for the advice everyone.

 

Since it's not a legal requirement and my motor is torque sensing, I'm not going to add them. Depending on how much wear I'm putting on the brakes, I'll consider upgrading them in the future.

Thanks for the advice everyone.

 

Since it's not a legal requirement and my motor is torque sensing, I'm not going to add them. Depending on how much wear I'm putting on the brakes, I'll consider upgrading them in the future.

 

Why would you skip installing brake sensors?

Emergency braking without sensors is the most effective way to ruin blue gear on TSDZ2B.

Why would you skip installing brake sensors?

Emergency braking without sensors is the most effective way to ruin blue gear on TSDZ2B.

Oh, you make a good point about the nylon gear... I didn't think about unintentional pedal force damaging the motor. Blast.

 

Having a look at my current brakes, there's no good place to mount the magnet style sensors, so I guess I'm buying the MT5e...

Why would you skip installing brake sensors?

Emergency braking without sensors is the most effective way to ruin blue gear on TSDZ2B.

There is no more blue gear on the tsdz2b and tsdz8.

There is no more blue gear on the tsdz2b and tsdz8.

 

What color is it? Blue on TSDZ2 and white on TSDZ2B? Color is actually irrelevant to what I was trying to say

They changed the design, inspired by bafang bbs01b. The fragile clutch part of bluegear is replaced by a double clutch placed under the main gear. Also, the antitorque bracket is optional.

Edited February 8, 20242 yr by Woosh

Brake cut outs are essential for two scenario's.

Approaching a junction you need to slow but keep pedalling to change down through the gears to allow you to start off in the right gear. Even more so with a mid drive.

During low speed tight mavouvres it's really best if the motor doesn't jump in and out. Or when riding shared use paths where there are dogs or kids wandering around. You want to get past them under pedal power alone.

I always fit one to the rear brake.

But it can be tough on my knees if I'm pedaling very hard when the motor cuts power at 25km/h, so I've become used to avoiding doing that via repeatedly painful negative reinforcement.

Yeah the cut off can be a pain. I was really surprised by it when you suddenly get the full weight of the bike(52lbs in my case) plus the slight lagging effect of the internals on the motor. It feels a bit like someone has thrown an anchor out the back

Tsdz2 doesn't need them , all my bikes that have used KT controllers again need no brake sensors. The only likely scenarion for them is if the need for throttle is fitted.

On my MTB I found them a pain and disconnected them. On my Greaser I have one on the front brake and find it useful. On my Puch Maxi they will be absolutely essential, because I need brake lights and electronic braking.

Cutoffs are also meant to be a safety feature in the event of a throttle stuck open fault through rain ingress etc, although I imagine most people would have the braking strength to overcome the motor.

Cutoffs are also meant to be a safety feature in the event of a throttle stuck open fault through rain ingress etc, although I imagine most people would have the braking strength to overcome the motor.

 

I guess it depends on how your bike is set up - I prefer assistance activating fast enough to make my bike easy to start pedalling, but not so fast I can't safely manage a U turn without needing to use the brake cutoffs too much (before firmware fiddling, it was all jumpy and lurchy). On precarious offroad parts and in chock a block slow moving stop/start traffic (my bike's usually too wide to filter, even with the Oxford sticking out from the right hand side handlebar-end and wing mirror folded in), brake cutoffs are essential for safety. The cadence sensing mid-motor driving my 20" wheels has a lot of torque, sometimes inches matter - it's well worth avoiding shooting a foot or so into space while on a narrow winding path along the edge a ravine for example. I am very rarely offroad, but when I am, every so often there's a ravine.

Edited February 9, 20242 yr by guerney

The isssue with over coming stopping issues (due to an open /faulty throttle ) is one will burn the controller out and then be stuck with a heavy unpowered bike to ride.

For bikes that use decent controllers with no over run issues then it is quite simple, fitted throttle then use one brake sensor , no fitted throttle no brake sensor needed.

Edited February 9, 20242 yr by Nealh

Tsdz2 doesn't need them , all my bikes that have used KT controllers again need no brake sensors. The only likely scenarion for them is if the need for throttle is fitted.

For bikes that use decnet controllers with no over run issues then it is quite simple, fitted throttle then use one brake sensor , no fitted throttle no brake sensor needed.

 

You've got a torque-sensing mid-drive which sips battery power, a totally different animal to my cadence-sensing battery guzzling mid-drive. I could make changes to my BBS01B's firmware parameters to render brake sensor cutoff unnecesary, use less battery power, but that would be at the expense of ease of pedalling, which I will not abide because I need to arrive at work completely sweat free and full of beans. Besides, the extra power is also useful for dragging heavy trailers up hills.

Edited February 9, 20242 yr by guerney

although I imagine most people would have the braking strength to overcome the motor.

Or the intelligence to hit the OFF switch, or lift the wheel off the ground while you find the off switch. The worst thing you can do is hold the motor still with the brakes when it's powered. You might end up burning to death. The least you'd get is a blown controller and/or burnt motor.

Or the intelligence to hit the OFF switch, or lift the wheel off the ground while you find the off switch. The worst thing you can do is hold the motor still with the brakes when it's powered. You might end up burning to death. The least you'd get is a blown controller and/or burnt motor.

 

Blimey that's a bit dramatic! Memorable image too - the BBC would love it if ebikers went up in flames screaming while gripping their brakes and burning to death at traffic lights all over the country. It'd spawn yet more fluffy and largely useless puff pieces about ebike battery safety. Thank goodness I have brake sensor cutoffs.

Edited February 9, 20242 yr by guerney