2019 ditch your rear disc brake ?

[cheapcookie]

Hey folks, been looking at a few recent threads recently, still love this stuff.

I see many builds wanting to keep +85% bicycle.

This makes me think...

What is worth keeping from the bicycle world as a result of a mid drive electric conversion/install.

In a hypothetical world, 1 or 2 stage direct driven 6 bolt disc brake mid drive mountain bike, vesc controller.

• 
  I doubt the usefulness of a rear disc brake (lightweight human) because of powerful front brakes and regen braking

• I double the usefulness of speeds, derailleur and cassette. Because of powerful top end and low end, added complexity

 

[Chalo]

Why keep the pedals?

 

[cheapcookie]

Why keep the pedals?

Why keep the handlebars, self driving eMTB 2020.

Edit: I go further/faster legally with pedals. With a flat battery, I also go further with pedals.

 

[Deafcat]

Rear brake: redundancy

derailleur gears: kinda super useful on mid-drives, also great redundancy on a hub motor ebike

Not saying you need em, and a bike can be built and ridden with many features deleted... But they all have some value.

 

[flat tire]

You are right, there is no need for rear disc brake with direct drive and good variable regen.

The only real reason to keep the disc brake is if your motor is too small to handle the additional thermal load generated from regen braking.

It's not needed for functionality with good variable regen, and it's not needed for safety because you still have a mechanical front brake that is responsible for all your stopping force anyway.

 

[AHicks]

A mid drive with regen braking? How does that work with the clutch in play? Is the rear wheel not free to spin on it's own unless under power? Seems like I have missed something somewhere along the line here...

I do have some direct drive hub regen experience, and based on that, trust me, you still want that rear brake!

 

[neptronix]

I ran no mechanical rear on my bike with strong regen ( 1kw of regen ). The rear did around 80% of the braking. It was awesome and a very efficient ride.

 

[Dauntless]

Why keep the pedals?

Why keep the bike? Get a hoverboard.

 

[cheapcookie]

Rear brake: redundancy

A lot of things have to go wrong for vesc6 and front hydraulic brakes to go out.
But you're right, I think the biggest failure point is battery, maybe others can confirm.
Although I could put some lights or some other power intensive device on the regen like the ODRIVE.

You are right, there is no need for rear disc brake with direct drive and good variable regen.

The only real reason to keep the disc brake is if your motor is too small to handle the additional thermal load generated from regen braking.

It's not needed for functionality with good variable regen, and it's not needed for safety because you still have a mechanical front brake that is responsible for all your stopping force anyway.

Puuuurfect

A mid drive with regen braking? How does that work with the clutch in play? Is the rear wheel not free to spin on it's own unless under power? Seems like I have missed something somewhere along the line here...

I do have some direct drive hub regen experience, and based on that, trust me, you still want that rear brake!

Sooo, right side of bike, AKA human powered side, has single speed freewheel.
Left side of bike has 6 bolt disc mount, on which is installed a sprocket instead.
Flip Flop hub works too, but more gearing down on first stage I guess, or small wheels.

 

[AHicks]

Sorry, this is new to me. Please help me get my head wrapped around this. I get the human powered side. It sounds like nothing is new there.

Would like more info on the brake side. Is there a link to this setup with more details?

The sprocket that has replaced the brake disk is now powered only by the motor? And there is no (free wheel) clutch in play? This motor employs some sort of internal transmission/multi gear ratio setup? Is there a "neutral" to allow the bike to freewheel?

Thanks!

 

[Drunkskunk]

In a hypothetical world, 1 or 2 stage direct driven 6 bolt disc brake mid drive mountain bike, vesc controller.

• 
  I doubt the usefulness of a rear disc brake (lightweight human) because of powerful front brakes and regen braking

• I double the usefulness of speeds, derailleur and cassette. Because of powerful top end and low end, added complexity

A 2 stage drive isn't a direct drive. With any kind of freewheel or one way bearing, you have no regen. You need a rear brake.
Also, regen braking is just a drag brake. it will slow you down, but not stop you. While some high end controllers have variable regen, it has no where near the modulation of a rear brake. If you're not also using a rear brake, you're not riding your bike anywhere close to it's potential.
For example, it would be impossible to perform proper trail braking with a Regen brake. Without a rear brake, you will be much slower through a corner.

A 1 speed bike is fine, for a hub motor. I've built several and geared them to be easy to pedal unpowered if I want to.
But this is the non-hub motor forum, and a non hub motor not running through a variable gear set is kind of missing all the fun and the point of a non hub motor. Variable gear trains let you run smaller, lighter motors with a wider torque range and higher efficiency under load.

 

[flat tire]

With any kind of freewheel or one way bearing

Well no shit. I think he has demonstrated an IQ above room temperature and is overwhelmingly likely to know that he can't regen with a freewheel and is instead talking about a high reduction ratio possibly with multiple stages but no freewheels. A 2 stage drive can surely have regen, just make sure the wheel spins the motor under load.

While some high end controllers have variable regen, it has no where near the modulation of a rear brake. If you're not also using a rear brake, you're not riding your bike anywhere close to it's potential.
For example, it would be impossible to perform proper trail braking with a Regen brake. Without a rear brake, you will be much slower through a corner.

You have NO clue. With ASI controller and left hand domino regen throttle, it is extremely easy to modulate the rear brake to balance the bike and trail brake while riding at the limit. The only difference is you cannot lock the rear brake, which is not a problem since if you ride at the limit of traction just hitting it a little bit will have the same effect. It also goes down to basically zero speed.

Really man don't talk out of your ass. Variable regen is a totally awesome solution and that should be overwhelmingly obvious.

 

[cheapcookie]

Just wanting to point out, this idea came from riding the bird segway's es2, and many other other e skateboards.

None of them have mech brakes, its all regen, guess what, it might not stop you at 60mph, but 25mph very well.

here is a thread with another person interested in regen middrive
https://endless-sphere.com/forums/viewtopic.php?f=6&t=100143

 

[cheapcookie]

Sorry, this is new to me. Please help me get my head wrapped around this. I get the human powered side. It sounds like nothing is new there.

Would like more info on the brake side. Is there a link to this setup with more details?

The sprocket that has replaced the brake disk is now powered only by the motor? And there is no (free wheel) clutch in play? This motor employs some sort of internal transmission/multi gear ratio setup? Is there a "neutral" to allow the bike to freewheel?

Thanks!

go have a look at the #25 sprockets section of electricscooterparts, pick 3 items chain, hub sprocket, motor sprocket, hopefully that helps visualize.

Edit: have a look at e skateboard, belt driving wheels, same thing but for a bike

 

[E-HP]

I haven't read too much on regen with a mid drive motor. Does that mean that braking power would also depend on the gear you're in, so more braking in lower gears and much less in higher?

 

[cheapcookie]

I haven't read too much on regen with a mid drive motor. Does that mean that braking power would also depend on the gear you're in, so more braking in lower gears and much less in higher?

Maybe you are thinking of downshifting a manual car or 4stroke bike?

Or maybe you are referring to gearing ratio ?

Edit: Forget the mid drive thing, the motor can be placed anywhere, the concept I and others are talking about is electric skateboard type drive on one side and human on the other.

 

[E-HP]

I haven't read too much on regen with a mid drive motor. Does that mean that braking power would also depend on the gear you're in, so more braking in lower gears and much less in higher?

Or maybe you are referring to gearing ratio ?

Edit: Forget the mid drive thing, the motor can be placed anywhere, the concept I and others are talking about is electric skateboard type drive on one side and human on the other.

Yes, the gear ratio between the wheel and motor affects the amount of regen braking force. Lower gearing, higher braking force.

 

[cheapcookie]

I haven't read too much on regen with a mid drive motor. Does that mean that braking power would also depend on the gear you're in, so more braking in lower gears and much less in higher?

Or maybe you are referring to gearing ratio ?

Edit: Forget the mid drive thing, the motor can be placed anywhere, the concept I and others are talking about is electric skateboard type drive on one side and human on the other.

Yes, the gear ratio between the wheel and motor affects the amount of regen braking force. Lower gearing, higher braking force.

This is correct, although motor choice, controller choice, load/battery choice, is probably more critical than gearing ratio.

 

[markz]

Or a moped/motorcycle/harley/scooter

Why keep the pedals?

Why keep the bike? Get a hoverboard.

 

[cheapcookie]

Or a moped/motorcycle/harley/scooter

Why keep the pedals?

Why keep the bike? Get a hoverboard.

...GET OUT OF HERE WITH THAT ICE MENTALITY. :lol: :lol: 8)

 

[markz]

You mean this kind of ice.

ICE

 

[DanGT86]

I have not ridden a bike with variable regen but I have serious doubts about riding without a mechanical lever actuated rear brake for a variety of reasons:

I like the modulation of regular brakes and the ability to lock up the wheel for trials type riding. If high end variable regen matches modulation of my disks but wont lock the wheel then I'm not giving up the brake.

Mechanical Braking is not limited by the thermal capability of the motor. I know brakes get hot too but they are designed for the job and I can feel their behavior change as I ride. Motor drive seems way more likely to surprise you when tasked with brake duty.

Handlebar brake levers are always in the same place in my hand regardless of terrain. Having a twist grip in both hands seems frightening in rough spots. With a twist throttle there is now zero static grip on the bars.

Regen on a mid drive requires a chain without spring tensioners. This is a serious engineering challenge on full suspension mid drive bikes. It also transfers the chain slack abruptly even on direct drive straight chain runs. I dont like that feeling especially in delicate traction situations. I believe the impact and forces acting on the parts of the drivetrain are worse than under acceleration and will wear parts faster. Also that chain slap really effects the modulation. With a mechanical brake you can keep the slack out of the chain through slick stuff by slightly dragging the brake.

 

[peters]

Electronics can't be considered as reliable as a mechanical brake. Without redundancy many components of the circuit are in series in the reliability model that means any of them fail you lose regen. That includes battery, bms, fuse, controller, components of the controller, connectors, firmware, regen throttle, wiring, motor, hall sensors and others.
I don't know the automotive standards, but sure that relying on regen only wouldn't be in compliance with them. Maybe ok for "toys" like skateboard and segway, but not for vehicles.

 

[cheapcookie]

You mean this kind of ice.

ICE

Not sure why u care bout meth in kangaroo land, when there's literally a planet of it in NorthAmerica

I have not ridden a bike with variable regen but I have serious doubts about riding without a mechanical lever actuated rear brake for a variety of reasons:

I like the modulation of regular brakes and the ability to lock up the wheel for trials type riding. If high end variable regen matches modulation of my disks but wont lock the wheel then I'm not giving up the brake.

Mechanical Braking is not limited by the thermal capability of the motor. I know brakes get hot too but they are designed for the job and I can feel their behavior change as I ride. Motor drive seems way more likely to surprise you when tasked with brake duty.

Handlebar brake levers are always in the same place in my hand regardless of terrain. Having a twist grip in both hands seems frightening in rough spots. With a twist throttle there is now zero static grip on the bars.

Regen on a mid drive requires a chain without spring tensioners. This is a serious engineering challenge on full suspension mid drive bikes. It also transfers the chain slack abruptly even on direct drive straight chain runs. I dont like that feeling especially in delicate traction situations. I believe the impact and forces acting on the parts of the drivetrain are worse than under acceleration and will wear parts faster. Also that chain slap really effects the modulation. With a mechanical brake you can keep the slack out of the chain through slick stuff by slightly dragging the brake.

Nobody said you couldn't lock up wheels up with regen.
In a nutshell, the same way ICE unconsciously encourages you to speed away from a green light.
Regen, encourages you to prepare, slow down, and engage a corner half a mile away.

Electronics can't be considered as reliable as a mechanical brake. Without redundancy many components of the circuit are in series in the reliability model that means any of them fail you lose regen. That includes battery, bms, fuse, controller, components of the controller, connectors, firmware, regen throttle, wiring, motor, hall sensors and others.
I don't know the automotive standards, but sure that relying on regen only wouldn't be in compliance with them. Maybe ok for "toys" like skateboard and segway, but not for vehicles.

Again, above we talked about how much has to fail to be down to so little
But as a generality, I know a few EEngineers on this forum that would like to disagree

 

[DanGT86]

Nobody said you couldn't lock up wheels up with regen.
In a nutshell, the same way ICE unconsciously encourages you to speed away from a green light.
Regen, encourages you to prepare, slow down, and engage a corner half a mile away.

You have NO clue. With ASI controller and left hand domino regen throttle, it is extremely easy to modulate the rear brake to balance the bike and trail brake while riding at the limit. The only difference is you cannot lock the rear brake, which is not a problem since if you ride at the limit of traction just hitting it a little bit will have the same effect. It also goes down to basically zero speed.

User Flat Tire just made that very statement as part of a glowing review on the benefits of variable regen. I was basing my statement on that since again I have not tried variable regen. I have used regular regen with chain driven mid-drive using a sprocket on the disk brake flange. That informs most of the points I mentioned previously.

As for preparing to brake early, its not always up to you as the rider. If you are making a leisurely cruiser for flat ground and not on public roadways or public paths then the front brake might be adequate. If you ride somewhere where joggers wear headphones, cars behave unpredictably, trails get wet, leaves fall on the ground, or any really technical terrain, I think rear brakes are a must.

Since brakes come on most bikes anyway I would suggest you design around using them and then take them off if they annoy you.

Also, if you plan to mess with wheelies I think a rear brake is a must.

An additional engineering challenge is chain management. The slack side of a chain without regen can have very light duty chain idlers like a derailleur. The jockey wheels are only controlling the weight of the chain. With regen they will get the full load of the tension if the chain so they better be strong structural components with good bearings. Say goodbye to cheap bike parts in that application.