Are mid drives just naturally less zippy than hub motors?

[SC00CHB00CH]

The Christini system is not quite what a lot of people think it is. It is not two wheels powered at once. There is a slight gearing differential - I think its like 97%. Maybe 95%. That keeps the front wheel from being actively powered. If the rear wheel slips, the front wheel takes over and pulls you out of your slide. When the rear stops slipping, it automatically shifts back to being primary. Its a subtle but significant difference. You aren't looking at more power so much as you are looking at it shifting fore and aft, as needed in the moment. He was interviewed on the Area 13 podcast awhile back after meeting the shop owner at Sea Otter. Its worth a listen if you want more on that concept.

Having done a few generations of 2wd bike myself, I can say they are pretty awesome. I have years, and thousands of miles, commuting on a hub/hub version, and my mid+hub can go places no other 2-wheeled bike can.

Dual Motor AWD Electric Bikes – Case Study: Fat Trail and Hill Climber

Built to conquer the weakness of twin hubs in hills – and eliminate the damage a mid drive does to an ebike’s drivetrain. The bike I call 2Fat did all that.

talesontwowheels.com

The question of whether a hub or a mid would work better in snow is moot. The tires and their inflation will decide that, up to the point where the single powered wheel is overwhelmed (the front wants to submerge from being pushed into the soft ground unless its powered and can pull itself up/out). Whether a hub is better than a mid in that world will be all about steepness. of the grade just like it is on dry ground.

In the video he using both wheels powered at once. He even shows you can disable 2wd and just use RWD. Is this a newer design since that interview? Because in the video both wheels are moving at the same time. The front wheel is moving and the rear wheel is moving ,they're both being powered at once by the mid-drive motor. Also isn't the power of the front hub on your bike slightly faster/slower than the mid-drive moving the rear wheel ? Wouldn't the same 95/97% apply to your build? Because both motors are independent of each other?

 

[m@Robertson]

In the video he using both wheels powered at once.

A gearing differential doesn't mean both wheels don't turn. It just means one or the other has torque behind it while the other one is to all intents and purposes freewheeling. They flip based on which wheel is getting traction. Its quite clever.

For the 2wd bikes I build, there is power and constant (albeit variable) torque to both wheels. They are two very different approaches and each has its plusses and minuses. The more crude iterations of dual-motor 2wd (see: E-cells, and apparently now Hummer) use a single throttle for both wheels.

How It Works - Christini AWD Bicycles

It is well-known what all-wheel drive does for a sport utility vehicle — just imagine what AWD can do for a mountain bike. Think traction control for your

christinibicycles.com

 

[SC00CHB00CH]

A gearing differential doesn't mean both wheels don't turn. It just means one or the other has torque behind it while the other one is to all intents and purposes freewheeling.

For the 2wd bikes I build, there is power and constant (albeit variable) torque to both wheels. They are two very different approaches and each has its plusses and minuses.

How It Works - Christini AWD Bicycles

It is well-known what all-wheel drive does for a sport utility vehicle — just imagine what AWD can do for a mountain bike. Think traction control for your

christinibicycles.com

So the mid-drive is only applying to torque to the rear wheel in his build? While the front wheel is freewheeling off the gearing mechanism off the rear? I Got it now

Your build looks awesome BTW!

"Hub drives power an ebike via the axle. They don’t – and they can’t – use the gears of the bike." <---- Love this quote

 

[m@Robertson]

So the mid-drive is only applying to torque to the rear wheel in his build? While the front wheel is freewheeling off the gearing mechanism off the rear? Got it

No. Read that article more carefully. Both wheels are turning via the mid drive. The gearing differential means the rear wheel does the work of propulsion so long as it gets traction. If it starts spinning, then that same gearing diff transfers power automagically to the front wheel. As the front wheel bails you out of the jam you are in, the rear wheel will regain traction at some point, which is when that power will again automatically shift to being delivered by the rear wheel.

You never get power from both wheels. Its one or the other depending on whether the rear wheel is spinning.

AWD Traction Control with Steve Christini, Founder of Christini Bikes | EP 102

Hey Everybody! Welcome back! It's another episode of the Bolton Ebikes Podcast. Recently at the Sea Otter Classic, I made a point to visit as many interesting electric bike vendors as I could. And one of those was Cristini bicycles because of their unique bicycles. I don't see anybody else doing...

www.area13ebikes.com

 

[m@Robertson]

Your build looks awesome BTW!

Worth noting - my twin hub bike is WAY more zippy than any mid drive can ever hope to be, including that mid+hub bike. All you do is stab'n'steer. And hang on. Versus losing time rowing thru the gears. the mid doesn't win until you throw in hills or nasty terrain. But then it wins big.

 

[SC00CHB00CH]

Worth noting - my twin hub bike is WAY more zippy than any mid drive can ever hope to be, including that mid+hub bike. All you do is stab'n'steer. And hang on. Versus losing time rowing thru the gears. the mid doesn't win until you throw in hills or nasty terrain. But then it wins big.

View attachment 139414

HAHA I don't agree , look at this ,mid-drive , this would scorch your dual hub. I would bet money on it . I wish they actually rode it though on video . The controller appeard to not have pedal assist when he got on it.

 

[fooferdoggie]

Worth noting - my twin hub bike is WAY more zippy than any mid drive can ever hope to be, including that mid+hub bike. All you do is stab'n'steer. And hang on. Versus losing time rowing thru the gears. the mid doesn't win until you throw in hills or nasty terrain. But then it wins big.

View attachment 139414

well zippy cause you haver a ton of power is like saying your motorcycle is zippy compared to my bike.

 

[Jeremy McCreary]

The Technological Imperative: If it can be done, it will be done. Doesn't have to be a good idea.

 

[AHicks]

The Technological Imperative: If it can be done, it will be done. Doesn't have to be a good idea.

I would add to that, it CAN be done if you throw enough time and money at it.

Further, if you stand there and say it can't be done, you're just incentivizing somebody that might know better. Might be WAY further ahead to step back and just watch (times to be 'talkin, and times to be 'listenen).

 

[linklemming]

@SC00CHB00CH
I think you have a lot of great ideas, but thinking maybe you're lacking overall experience/seat time with the different options available here. What the hell am I talking about? Get back with us when you've built and spent some time with a similar bike with GMAC power, a 1000w MAC geared hub, or maybe one of the new Bafang 1000w geared hubs for instance. Then you can compare apples with apples best possible.

The subject being discussed here has NOTHING to do with how fast your bike or any other bike will go. This is way more about a drag race to 10mph or so. Who can cross the road in the quickest manner possible. Zippy......

Comparing what you have going on with your bike is hardly typical.... but I'll give you a hint. All else being equal, I feel pretty safe predicting your bike will be smoked in a race across a street by one just like it with a 1000w+ geared hub power and a power supply that will stay up with it (35a+). Beyond that, for our subject at hand, nobody cares....

Lots of interesting twists and turns in this thread as well as apples to oranges comparisons so I thought it might be a good time to throw my thoughts in the mix.

I have two identical DIY high power ebikes (52V, 30A, 1500w). They are both built off Sulry Ogre Framesets and every component is identical except for tires/rims/hubs.

I ride these bikes alternating each day on the same trails.

Bike#1 GMAC 10T with phaserunner and CA3
Bike#2 BBSHD

I could give quite an essay on this subject, if really interested, go to my thread on the build(s). https://electricbikereview.com/forums/threads/my-new-custom-gmac-build-now-a-bbshd-as-well.38385/

I can also elaborate more here if people want.

In a nutshell as far as 'being zippy', its Bike#1 all day long, Sure I can gear down Bike#2 for a short quick takeoff from a stop but quickly run out of rpms and need to shift.
Each shift requires a delay to preserve the driveline. Bike#1 while maybe not having the initial 1 second burst of acceleration of Bike#2, all things considered its WAY faster
getting up to speed and no pauses need for upshifts.

Only area the BBSHD really shines is inclines above 10%. Below 6%, the GMAC excels under every condition....at 8% they are about equal. The BBSHD also has better weatherproofing. The BBSHD also has more nimble handling due to the low centrally located motor.

The GMAC is better in every other scenario. My rides are typically 20-30 miles, 1500ft-2000ft elevation, 4-6% 'average' grades (some grades up to 20% for short distances), headwind on the way home typically 15+mph. Most power demanding part of ride is going up a 6% grade battling 15+mph winds for a few miles at the end of the ride where I am usually at max power.

I have been all over the place as to which is the better bike (initially built GMAC, then BBSHD, then exclusively BBSHD, now GMAC and BBSHD)

There is so much more I can add, I will wait to see if anyone is interested.

FWIW, all my neighbors prefer the GMAC hands down

I have several nice brose mid-drives besides the BBSHD (iZip Moda, Bulls Evo 3, 2022 Specialized Turbo Levo)

 

[Johnny]

A mid vs hub zippiness thread, lovely!

As stated a million times, Hub motor rpm depends on speed , mid motor rpm depends on the cadence. The reason why Hubs feel zippier is most likely a result of the need to change gears with a mid drive to keep it at the right rpm.

"Mid-drives provide a higher-performance experience in every respect."

"Hub motors are roughly 30% efficient, while a mid-motor from Bosch is designed to run at about 70% to 80% efficiency," said e-bike drive system engineer Zach Krapfl,

Most likely the reporter messed it up. A decent engineer wouldn't say this nonsense. At %30 efficiency that thing is a heater rather than a motor. If he really did then he doesn't know what he is talking about...

This nonsense about efficiency is tiring. Human beings like to ride at varying speeds and varying cadences hence one(mid,hub) is not more efficient than the other in all cases. "Usually" High speeds or riding at lower cadences favor hub motors while higher cadence, slower speeds favor mid drives. So mid drives will be cadence sensitive, hubs will be speed sensitive what is so hard to understand?

And when you put a motor to assist you what you are riding is no longer a bicycle! It is not the location of the motor. Regardless of the location, it is transferring power to the rear wheel which propels you forward.

It is absurd as hell to claim that if the motor is located in the mid it is a "bicycle" otherwise motorcycle. Stop being irrational snobs!!!

 

[SC00CHB00CH]

A mid vs hub zippiness thread, lovely!

As stated a million times, Hub motor rpm depends on speed , mid motor rpm depends on the cadence. The reason why Hubs feel zippier is most likely a result of the need to change gears with a mid drive to keep it at the right rpm.



Most likely the reporter messed it up. A decent engineer wouldn't say this nonsense. At %30 efficiency that thing is a heater rather than a motor. If he really did then he doesn't know what he is talking about...

This nonsense about efficiency is tiring. Human beings like to ride at varying speeds and varying cadences hence one(mid,hub) is not more efficient than the other in all cases. "Usually" High speeds or riding at lower cadences favor hub motors while higher cadence, slower speeds favor mid drives. So mid drives will be cadence sensitive, hubs will be speed sensitive what is so hard to understand?

And when you put a motor to assist you what you are riding is no longer a bicycle! It is not the location of the motor. Regardless of the location, it is transferring power to the rear wheel which propels you forward.

It is absurd as hell to claim that if the motor is located in the mid it is a "bicycle" otherwise motorcycle. Stop being irrational snobs!!!

A mid-drive relies on the chain , sprocket and rear cassette to propel the bike forward. Just like a human pedaled bikes does. A rear hub motor does not use the bicycles front sprocket , chain or rear cassette to propel the bike forward.

You could remove the cranks , pedals , front sprocket and rear cassette with a rear hub drive and the bike will still move forward without any input from the rider other than hitting the throttle. The same can't be said for a mid-drive which relies on the mechanism of a bicycle ,chain , sprocket and rear cassette. If you removed the chain from a mid-drive you wouldn't move an inch.

The typical definition of a bicycle. Both human powered bikes and mid-drives rely on the same mechanism to propel the bike forward. Rear Hub motors do not.
In this instance mid-drives are more bike-like than rear hub motors in that both human powered bikes without a motor and mid-drive powered bikes both utilize the same bicycles gearing.

Again we're replacing emotion with mechanical facts. Which is the foundation of all the misconceptions in this thread about mid-drives versus hub drives.
I'm all for team hub drive but I can't replace facts with emotions. The mechanisms of the two bike styles are actually respectably different.

 

[Johnny]

The typical definition of a bicycle. Both human powered bikes and mid-drives rely on the same mechanism to propel the bike forward. Rear Hub motors do not.

I know no such typical definition.

Here are some definitions from well known dictionaries "a vehicle with two wheels tandem, handlebars for steering, a saddle seat, and pedals by which it is propelled", "a road vehicle with two wheels that you ride by pushing the pedals with your feet". https://www.britannica.com/summary/bicycle , https://dictionary.cambridge.org/us/dictionary/english/bicycle , https://www.collinsdictionary.com/us/dictionary/english/bicycle .

So the power must be generated by propelling the pedals!!! Just because a mid drive is connected to rear wheel by a chain doesn't satisfy that requirement. When the chainring is rotated by the motor, the power is still NOT generated by propelling the pedals.

Here is a "mechanical fact" for you, most of the motorcycles also have sprockets and a chain that transmit power from the motor to the rear wheel hence the mechanism is actually very similar to a mid drive with throttle...

 

[SC00CHB00CH]

I know no such typical definition.

Here are some definitions from well known dictionaries "a vehicle with two wheels tandem, handlebars for steering, a saddle seat, and pedals by which it is propelled", "a road vehicle with two wheels that you ride by pushing the pedals with your feet". https://www.britannica.com/summary/bicycle , https://dictionary.cambridge.org/us/dictionary/english/bicycle , https://www.collinsdictionary.com/us/dictionary/english/bicycle .

So the power must be generated by propelling the pedals!!! Just because a mid drive is connected to rear wheel by a chain doesn't satisfy that requirement. When the chainring is rotated by the motor, the power is still NOT generated by propelling the pedals.

Here is a "mechanical fact" for you, most of the motorcycles also have sprockets and a chain that transmit power from the motor to the rear wheel hence the mechanism is actually very similar to a mid drive with throttle...

I'm not sure the point you're trying to make here.

With pedal assist both human legs and the mid-drive motor provide power through the chain ring to propel the bike forward. A mid-drive doesn't need pedals because it's not a human that has feet , it's a mechanical part called a motor. The pedals are for human feet to move the cassette forward and the mid-drive is mounted inside the bottom bracket connected to the same chain-ring both achieve the same result by propelling the chain-ring with a chain wrapped around it tied to a rear cassette. This basically is the bread and butter of bicycles and propels the bike forward.

The mid-drive uses the front chain ring to propel the bike ,this same chain ring is propelled also by the pedals of the rider if needed ie: pedal assist . Both mechanisms use the front chain-ring and the chain along with the cassette to power the bike forward. Why is this simple mechanism not registering with some of you.
The rear hub motor needs NONE OF THIS to propel the bike forward. It's basically a moped disguised as a bike where a mid-drive still uses the same bike mechanics as a human power bicycle.

 

[Johnny]

A mid-drive doesn't need pedals because it's not a human that has feet

Lol, yeah motors dont have feet.

whatever.

 

[SC00CHB00CH]

Lol, yeah motors dont have feet.

whatever.

sarcasm meter detected

 

[AHicks]

A mid-drive relies on the chain , sprocket and rear cassette to propel the bike forward. Just like a human pedaled bikes does. A rear hub motor does not use the bicycles front sprocket , chain or rear cassette to propel the bike forward.

You could remove the cranks , pedals , front sprocket and rear cassette with a rear hub drive and the bike will still move forward without any input from the rider other than hitting the throttle. The same can't be said for a mid-drive which relies on the mechanism of a bicycle ,chain , sprocket and rear cassette. If you removed the chain from a mid-drive you wouldn't move an inch.

The typical definition of a bicycle. Both human powered bikes and mid-drives rely on the same mechanism to propel the bike forward. Rear Hub motors do not.
In this instance mid-drives are more bike-like than rear hub motors in that both human powered bikes without a motor and mid-drive powered bikes both utilize the same bicycles gearing.

Again we're replacing emotion with mechanical facts. Which is the foundation of all the misconceptions in this thread about mid-drives versus hub drives.
I'm all for team hub drive but I can't replace facts with emotions. The mechanisms of the two bike styles are actually respectably different.

You're getting side tracked. Let's focus on "zippy", hub drive vs. mid.

Clearly, those that have a lot of seat time on both types seem to be in agreement. Anyone looking for an unbiased answer here has to wonder why that might be.....

 

[MinnBobber]

IMO, hub drives AND mid drives without a throttle are bicycles.
Hub drives AND mid drives with a throttle…..
they are electric mopeds. No pedaling necessary

Our state of MN also uses that as the legal definition of bikes allowed to use official bike paths.

It does not matter where the bicycle supplemental power is located, but it is supplemental (in addition to required pedaling).

 

[m@Robertson]

Why should anyone care? (answer: ego. Nothing more)

 

[m@Robertson]

HAHA I don't agree , look at this ,mid-drive , this would scorch your dual hub. I would bet money on it . I wish they actually rode it though on video . The controller appeard to not have pedal assist when he got on it.

HAHA yourself. Its one thing to watch a video and its another entirely to know these motors and bikes from experience.

That little bike in the video is powered by a 3kw mini Cyclone kit. They were powered by a 60a Kelly controller that Luna was doing the programming for pre-sale. Want to see another one (I didn't spring for the Luna Tick alloy chainring in that video)? Want to see the instructions on how to install it? They are on the Luna forum. I wrote them. You will see this bike there in the pics.

This was, by the way, October of 2017, which is two months after your video was taken (which I watched at the time, pre-sale. Battery in it was a 52v 12ah Samsung 25R pack). In that video, the motor peaked at 62a. I didn't hear a wattage peak in the vid but mine peaked right at around the same amps. Peak wattage was about 4000w, not the advertised 3000.

So... rather than you watch a video and read it wrong, I can just tell you how they worked.

The Mini Cyclone had very high rpm's which is amply demonstrated by the guy holding it in the air and letting the motor spin it up. But... they are gutless. All horsepower (rpms) and no torque. Apply a load to the motor and it bogs down. To solve that It is essential to downshift at a stop 3+ gears, and then row thru them as you came off the line and get up to speed.

If you tried to run that motor under load without managing throttle - so those 60 amps are only used to make it go forward - it overheated and the controller shut it down. Then you had to sit on the side of the road for 10 minutes while it cooled enough for the controller to let it come back on. Once I learned how to feather the throttle (PAS did not exist) I was fine so long as I stayed off my 12T gear and let the motor keep the rpms up... after ramping up thru the gears. Top speed was about 33-35mph in that next-to-top gear on this bike, bearing in mind my 250 lbs, which were a major limiting factor. Also necessary to stave off overheating during my commute even after feathering the throttle were heat sinks all over the motor, as you can see installed below. These were worth quite a bit. Something like 40 degrees of surface temp but they made the difference internally between a shutdown and a successful arrival at the office from home.

But put all that aside... Cyclones were and are known to taco chainrings and tear chains apart (zoom in on that first pic and look at what kind of chain I used for the primary off the motor). The video you liked so much shows a guy spinning the motor under zero load. But look at the very end of the vid when he tries to ride it. They ended up fixing that as well as they could by the time they started selling them, but bottom line is you cannot watch a motor whiz around with no load and have the slightest clue what it will do with a rider on top.

So... you row thru the gears with that motor. Which was kind of fun as the bike - with no PAS and no display, was kind of like a little crude sports bike all rough around the edges. Remember this was 2017 and there were different expectations of what a DIY bike should be. Just look at all the zip ties I used.

So... THAT is how a hub motor - with sufficient power - beats a mid drive off the line. Hub motors need no shifting. Their acceleration curve is smooth and continuous with no gaps. Mids - even with a gear sensor - need a pause in acceleration to shift, and when they do they have to ramp the power back up. It sounds EXACTLY like a car and it has exactly the same negative effect in a drag race.