From Class 2 to Class 1. How "hard" is it to switch?

[speedub.nate]

Most hub-motor bikes have brake cutout levers. The levers have an electrical wire that goes to a switch.

Oh? I suppose that is reasonable and even practical.

@kevinmccune nope this one is mid drive, and with no such brake lever interface.

 

[Jeremy McCreary]

There are several issues with a throttle.

You will get used to not pedalling.
You can catch it while standing stationary and fire off into danger.
It can get jammed on passing foilage and end up with a uncontrolled bike.
There can be strange relationships netween the throttle and the cadece/torque sensor, especially on cheaper bikes.
I have had a throttle stick wide open, and if you dont have cutoff brakes, things can get interesting.
Nosey tyre kickers can push the throttle while its leant against something just to see what it does.

Really? Never once had ANY of those problems in over 3,000 mi on my heavy 500W torque-sensing commuter with progressive on-demand thumb throttle. Not even close.

Especially that nonsense about not getting used to pedaling. Nothing about having a properly implemented throttle at your disposal forces you to ride without pedaling.

In fact, I always pedal that commuter with effort by choice — and not just ghost-pedal. Use the throttle only a few seconds at a time ON TOP of pedaling as the need arises. Doubt if even 1% of my miles on that bike have been under throttle, pedaling all the while. But I'm sure glad that bike has one.

There are many valuable uses for a throttle that have absolutely nothing to do with getting out of pedaling — especially on a heavy torque-sensing ebike. That includes starting out and instant bursts of speed in traffic. I consider the latter an important safety feature on my commuter. Also an invaluable knee-saver in my case.

In contrast, I have no real need for a throttle on my much more responsive lightweight fitness mid-drive. But still miss it in traffic at times.

 

[Chargeride]

Ive had everyone of them, youve just been lucky, theres quite simply twig jammed throttle bikes careeing over cliffs all over the world right now.

 

[speedub.nate]

So is this safety switch connected to a brake lever also found on mid-drive bikes that are equipped with throttles?

A brake pedal motor cut-off is common, maybe even standard, in electric cars. You can imagine it causes a problem for two-foot drivers. Most EV drivers on the forums don't even know it's there.

Searching the web I see brake levers wired with this feature, including some made by Shimano, but none with a SD50 or SD300 plug that could easily be connected to a free port on the display. What is the rationale that this is a prudent feature on a hub drive bike, but not warranted for any of my Shimano or Bosch mid-drives? (all throttleless)

 

[RunForTheHills]

So is this safety switch connected to a brake lever also found on mid-drive bikes that are equipped with throttles?

A brake pedal motor cut-off is common, maybe even standard, in electric cars. You can imagine it causes a problem for two-foot drivers. Most EV drivers on the forums don't even know it's there.

Searching the web I see brake levers wired with this feature, including some made by Shimano, but none with a SD50 or SD300 plug that could easily be connected to a free port on the display. What is the rationale that this is a prudent feature on a hub drive bike, but not warranted for any of my Shimano or Bosch mid-drives? (all throttleless)

It is recommended for safety reasons, but many people don't use one. If the brake is on and you accidently press on a pedal with a torque sensor or touch the throttle, the bike will lurch forward. A throttle can also get stuck and pulling the brake lever will disable the motor. If your display/controller doesn't support an ebrake sensor, then you can't install one. They sell brake levers with integrated switches or sensors you can add to an existing brake lever (Usually with epoxy or glue).

 

[speedub.nate]

It is recommended for safety reasons,

What I'm getting at is that my ebikes have been all reputable brands i.e. Shimano / Bosch drive systems, from Raleigh / Felt / Bianchi / Yuba / Electra (Trek). None have had this feature. I would expect that if this was recommended for safety, I'd have come across one in the past 10 years. I'm in agreement, it seems like a prudent feature. There must be a very compelling reason why this hasn't been included.

 

[RunForTheHills]

What I'm getting at is that my ebikes have been all reputable brands i.e. Shimano / Bosch drive systems, from Raleigh / Felt / Bianchi / Yuba / Electra (Trek). None have had this feature. I would expect that if this was recommended for safety, I'd have come across one in the past 10 years. I'm in agreement, it seems like a prudent feature. There must be a very compelling reason why this hasn't been included.

They obviously exist for a reason. I can't speak to the bikes you have owned. It is certainly possible to ride an ebike without one and many people do.

 

[Gionnirocket]

What I'm getting at is that my ebikes have been all reputable brands i.e. Shimano / Bosch drive systems, from Raleigh / Felt / Bianchi / Yuba / Electra (Trek). None have had this feature. I would expect that if this was recommended for safety, I'd have come across one in the past 10 years. I'm in agreement, it seems like a prudent feature. There must be a very compelling reason why this hasn't been included.

I know a lot of MTB riders disable the brake cut out as it can interfere with aggressive technical riding.
All Bafang mid drives and hub motors have this feature as well as most diy kits and hub drives.
Can you get by without one... Well you're proof it's not an absolute necessity.
Me on the other hand have had them on my bikes and appreciate the added safety and even use them strategically to briefly cut off the motor but still pedal without having to turn off assistance such as navigating a narrow barrier with wide open trail on each side.

 

[Chargeride]

A backpack battery is a good safety feature, you can just pull the plug and it automatically disconnects if you exit the bike into the scenery.

Dont use a backpack battery though.

 

[speedub.nate]

Me on the other hand have had them on my bikes and appreciate the added safety and even use them strategically to briefly cut off the motor but still pedal without having to turn off assistance such as navigating a narrow barrier with wide open trail on each side.

Thank you for that reasoned answer, that seems like a good alternate use -- as does another rider who said he would lightly squeeze the brake lever to cut the motor briefly while completing a shift under load. I found some references to CA vehicle code 406(a) that used to read (paraphrasing) "must cut motor power when brake is activated OR be equipped with a throttle or mechanism that disengages the motor when released" though that section of code has been heavily rewritten since that time in the early 2000s.

However common web forum sentiment seems to be that torque sensing motors negate this as a necessity, whereas cadence sensing don't.

Still... Shimano and Bosch usually both lean towards conservative rule interpretation, and I'm still searching for their thinking on the matter. And two of my bikes -- one each w/ Shimano and Bosch -- are Class III / 28 MPH no throttle and if any would have a cut-off I'd expect it'd be them.

I'll keep poking around, I'm sure I'll find some obscure Shimano document.

 

[PedalUma]

MTB riders disable the brake cut out as it can interfere with aggressive technical riding

For me this is exactly correct. You know how you could do a burnout in mom's station wagon when you applied the brake first to get some revs? The same goes for a quick turn or hopping up a curb. It is for when you need to slow but quickly recover speed. In my opinion cutouts are a holdover from the days of front hub drives. Before them kids could apply the rear brake and peel out the front wheel in mud, gravel, or snow. But that is also where steering happens. Not a good combination.

 

[Stefan Mikes]

Nate, the matter is actually very simple.
The throttle has nothing to do with the pedalling. If you pulled brake levers but the throttle were engaged for whatever reason, the motor would act against the brakes, making the whole situation inherently unsafe. That's why brake lever activated hub motor cut off switches should be used.

With a mid-drive motor, you never pedal when you engage the brakes, so the motor instantaneously cuts off. (I'm not discussing rare and intentional solutions such as the "motor overrun" found in some advanced e-MTBs). No need for the brake cut off switches in a respectable mid-drive motor system.

There were attempts to apply the switches to cut the mid-drive motor off for shifting but I think it is not being done anymore as the rider would ease on or stop pedalling during the shifting. (Shifting while pedalling is not critically bad. The new SRAM Transmission -- or Type T -- drivetrain even encourages riders to shift under the load).

 

[6zfshdb]

My Pedego has brake cutout levers but I was concerned about an electrical failure. A couple of years ago, as an experiment, I disconnected the brake switches and took a ride. I held the throttle wide open and the disc brakes easily stopped the bike and stalled the 500W hub motor from a speed of 15mph. From a dead stop, I firmly applied the rear brake and applied full throttle. The motor groaned loudly but the rear wheel didn't spin.

I can't speak for other bikes, particularly those with high power motors or different brakes, but the cutout switches aren't absolutely necessary on mine.

 

[Gionnirocket]

For me this is exactly correct. You know how you could do a burnout in mom's station wagon when you applied the brake first to get some revs? The same goes for a quick turn or hopping up a curb. It is for when you need to slow but quickly recover speed. In my opinion cutouts are a holdover from the days of front hub drives. Before them kids could apply the rear brake and peel out the front wheel in mud, gravel, or snow. But that is also where steering happens. Not a good combination.

I slow and quick recover all the time without issue. One of the benefits of 1000w at your disposal. And you can't slow and accelerate simultaneously no matter what.
As with any setup you learn different ways to get what you want/need when you want/need. Brake cut out are not a necessity, but I don't see any drawbacks in my riding. And as mentioned it can even be an added tool as well as a safety feature. Safety should never be marginalized as you might never need it except that one time. . .

 

[Stefan Mikes]

I held the throttle wide open and the disc brakes easily stopped the bike and stalled the 500W hub motor from a speed of 15mph. From a dead stop, I firmly applied the rear brake and applied full throttle. The motor groaned loudly but the rear wheel didn't spin.

Don't you think powering a stationary motor would release all the power as heat inside the motor?

How do you "stall" an electric motor? It is not an ICE engine that can be stalled. Unless the heat release in the hub has tripped the thermal protection relays.

 

[speedub.nate]

With a mid-drive motor, you never pedal when you engage the brakes, so the motor instantaneously cuts off. (I'm not discussing rare and intentional solutions such as "motor overrun" found in some advanced e-MTBs). No need for the brake cut off switches in a respectable mid-drive motor system.

Ah, true, except when it's not. The whole reason this thread forked is I mentioned my wife has suddenly had a few motor "excursions" while rolling to a stop on her new-to-her bike. What I wrote earlier is that it's almost for sure some habit she needs to unlearn, but a kill switch on the brake lever would have definitely prevented this.

There were attempts to apply the switches to cut the mid-drive motor off for shifting but I think it is not being done anymore as the rider would ease on or stop pedalling during the shifting.

I still see this as an advertised feature with current generation Shimano and Bosch motors, and specifically for shift gear hubs.

 

[Stefan Mikes]

Ah, true, except when it's not. The whole reason this thread forked it I mentioned my wife has suddenly had a few "excursions" while rolling to a stop on her new-to-her bike. What I wrote earlier is that it's almost for sure some habit she needs to unlearn, but a kill switch on the brake lever would have definitely prevented this.

Please remind me what make and the model/Gen of the motor it is? Some motors have the "overrun". It is a feature for the following scenario: a mountain biker has ridden into a very short stretch of the terrain where pedalling is impossible; it could be a very short and shallow ditch across the trail. The rider must ride through the hole but cannot pedal because of pedal strikes. The motor overrun powers the e-bike for a short distance/time, so the rider can cross the obstacle without pedalling. As the feature is potentially unsafe, it can be switched off in the e-bike app.

I still see this as an advertised feature with current generation Shimano and Bosch motors, and specifically for shift gear hubs.

Possibly. No experience with these.

 

[Gionnirocket]

On a Bafang the overrun time is programmable. I keep it to a minimum but not 0 as it aides in general smoothness when pedal pressure varies or during brief pauses.
It's much more desirable, accurate and safe to millisecond throttle to avoid pedal strikes.

 

[speedub.nate]

Please remind me what make and the model/Gen of the motor it is?

Bosch Performance Line CX from the 2022 model year on a Bianchi step-thru city bike.

 

[PedalUma]

You know how in a sports car going into a turn you can apply the brake with your left toe, the heal on the clutch while you downshift into second and while slowing give it revs with the right foot and pop the clutch and off the brake while accelerating out of a corner? That is why I do not like cutouts personally.