Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[Richard230]

If electric motorcycles had a gearbox, the next thing you know an "oil thread" would be created on this forum.   

A great reason for not having a transmission.   

[mrwilsn]

I'd prefer a clutch to be honest.

When the backside kicks out it's nice to be able to disengage the spinning mass from the rear wheel.

I agree. Especially since we have no traction control on the Zero. But wouldn't be worth a whole transmission just to get that ability. The next option would be to add a clutch just for the single gear but sadly I doubt Zero has the R&D to design considering the short list of benefits.

I thought about wiring up a lever and tying it in to the motor kill switch to create an electronic version to just be able to cut power faster than I'm able to with the throttle. But I'm not sure how effective it would be at mitigating a low side and it would take a second once re-engaged to get power again which would be annoying at the least.

Sent from my Nexus 6P using Tapatalk

[Killroy]

It seems like traction control would be a lot easier to implement than adding a transmission and a clutch. 

There is a lot of user error when people shift gears and clutch.  You can hear the errors in lots of Youtube videos. 

[Erasmo]

I'd prefer a clutch to be honest.

When the backside kicks out it's nice to be able to disengage the spinning mass from the rear wheel.

There is almost no spinning mass compared to an ICE. Let go of the throttle and the regen will actively counter the spinning mass.

[Justin Andrews]

I'd prefer a clutch to be honest.

When the backside kicks out it's nice to be able to disengage the spinning mass from the rear wheel.

There is almost no spinning mass compared to an ICE. Let go of the throttle and the regen will actively counter the spinning mass.

Good point, I wonder how close the spinning mass of the output side of the clutch compares to the rotor of the motor, I'd imagine there is not a great deal in it, and as you say, the output side of a clutch cannot act as a counter the way a motor in regen mode can.

[frodus]

My thoughts: Back in 2013 when I bought mine, I'd still have chosen a Brammo because of the look and fit and finish looking cleaner and more refined. The transmission wasn't really a selling point for me, but I do see the merits. I'd likely go with a Zero today, though not because of direct drive, but because of it's range and performance. In the end, it didn't really matter to me.

So, a lot of posts about direct being better than transmission, but is that really true across the board?

Torque on the Brammo R is 90Nm and it has 54HP. Zero SR has 144Nm they have 67HP. One decided to go with a slightly larger motor with more torque and direct drive it, the other decided to put a smaller motor and a transmission to get them the torque they wanted, but over a larger vehicle speed.

Yes each have their benefits. The Zero (aside from belt) is pretty much zero maintenance and more efficient in its conversion of torque to the rear wheel. The transmission has infrequent transmission oil changes, and likely no need to change the clutch. It's less efficient, but allows you to always put the motor in it's more efficient RPM range, something direct drive cannot do (at least not at all speeds).

I did some calculations on the torque on a Zero SR and Brammo Empulse R:
Here's the Zero:
http://electricmotorcycleforum.com/boards/index.php?topic=3872.0

Here's the Brammo:
http://electricmotorcycleforum.com/boards/index.php?topic=3871.0


The Brammo has a smaller motor with 90Nm of torque peak. Notice the Brammo has 2760N of force at the rear tire (where the rubber meets the road) in 1st gear from a stop.

The 2014 Zero SR, had a little larger motor (bigger diameter) with more torque at 144Nm. Notice here that the peak torque on the rear rubber is 1983N. Even with the newer motors and 157Nm of torque and a 4:1 ratio (before it was 4.4:1), you get 1966N of torque at the rubber (slightly lower than 2014). In fact, the Brammo has mote torque at the rear rubber than the Zero SR (2014 until today) in 1st and 2nd gear. 1st gear has ~775N more force and 2nd gear has about 275N more.

Not poo-pooing Zero at all, but there are merits to a transmission.

Transmission Pro:
Can get the motor in it's peak efficiency RPM
Can change torque output on the rear wheel


Transmission Cons:
Less efficient (but could actually pick up gains by putting the motor in it's peak effieincy part of the motor curve)
More maintenance (but minimal in my experience)
More moving parts
More expensive (We're all guessing here though, is a larger motor and direct drive cheaper than smaller motor and off-the-shelf transmission?)
Transmission lash is noticable

Direct drive Pro:
More efficient
Less Maintenance
Less moving parts

Direct drive Cons:
Cannot change the torque output on the rear wheel
Can potentially lock up the rear wheel if there's a catastrophic motor failure
Cannot put the motor in peak efficiency (which could, in theory negate any gains made by direct drive)


Anyway, this is just using the specs on each, there's nothing to argue here. Just fact and showing some of the pro's and cons of each.

I'd by a Zero today if I was looking for a bike, because of the range and support and refinement the last few years, not because of the direct drive.

[Low On Cash]

Frodus

Thanks for the detailed reply and most important, sharing the torque advantage comparisons using a transmission - Your Rear Wheel calculations clearly shows the torque advantages of using a transmission. It boils down to the fact any motor will be more efficient and powerful at its designed operating RPM.

Do we need a transmission - possible not, but just because Zero decides not to use one, which I’m sure was from a cost stand point, does not mean others will follow. Brammo did get one thing right - guys like shifting gears.

As an example - The best motorcycle transmission in the world, which I own two bikes with; is the Honda DCT (Dual Clutch Transmission) The DCT is a 6 speed computer controlled transmission that may be shifted manually as well. The DCT is the most efficient and the fastest shifting transmission made. By using one clutch for 1,3,5 gears and a second clutch for 2,4,6 gears, it allows the transmission to shift from one gear to another by simply releasing one clutch and engaging another, its lightning quick since its actually in both gears at one time prior to shifting. Testimonial to the fact just how good the DTC is; is used by many luxury and sports such as the Porsche 911, Mercedes GT-S, BMW M4, Alfa Romeo 4C, Acura NSX, and others, some costing over a million dollars since it is the most efficient (no hydraulic converter) and can shift faster than any human being or any hydraulic transmission.

Getting back to my point - even though this transmission is the most advanced in the world - Guess What? it was never accepted by the motorcycle industry for the simple fact that riders like doing stuff when they ride and shifting is one of them.

Thanks - Mike 

This is the Honda NM4 Limited Production bike with the their DCT system - because of its aerodynamic design and efficiency of the Dual Clutch Transmission and engine this bike achieves up to 80 miles per gallon. 

[Richard230]

My Honda dealer says that the DCT transmission has increased their Honda sales considerably.  They claim that new riders don't want a manual transmission, or the need to shift or operate the clutch.  They are much happier with an automatic transmission, which makes motorcycles much easier to ride, especially in urban traffic.  Personally, I like not having to shift my Zero, after shifting motorcycles for 55 years.  It just makes the ride more enjoyable for me.     One of the reasons that I bought a Zero instead of a Brammo when the Empulse finally hit the market was because it had a 6-speed transmission and I preferred the simplicity of the Zero design.   

[benswing]

Also zero isn't the only EV manufacturer to use a single gear.  All of the major manufacturers of EVs use it.  So this isn't a Zero Motorcycles simplicity thing, it's the industry standard for a reason. 

Not that there aren't advantages, and I appreciate the detailed analyses provided here. Very interesting.


Sent from my iPad using Tapatalk

[frodus]

Also zero isn't the only EV manufacturer to use a single gear.  All of the major manufacturers of EVs use it.  So this isn't a Zero Motorcycles simplicity thing, it's the industry standard for a reason. 

Not that there aren't advantages, and I appreciate the detailed analyses provided here. Very interesting.

Exactly, the reason they chose it isn't necessarily performance (maybe cost and simplicity driven?). And to your point, Brammo isn't the only EV manufacturer that has used a transmission, and likely won't be the last. Just different manufacturers solving an end goal with 2 solutions.

Also, if I recall correctly, Tesla had a terrible time not breaking transmissions with all that electric motor torque!

#ilovemybrammo

[Snafuperman]

If electric motorcycles had a gearbox, the next thing you know an "oil thread" would be created on this forum.   

A great reason for not having a transmission.   

Now that's funny . . . and true!  Every m/c forum I've ever been on had at least one oil thread going at any time.  On the H-D forums there were more like 3 or 4, each dumber than the last one.

[clay.leihy]

My first shift-less bike was the Honda Silverwing scooter. It was positively liberating, especially in city traffic. It was kind of slow "off the line" but the Zero certainly doesn't have that problem. 😀

Sent from my Z981 using Tapatalk

[Richard230]

If electric motorcycles had a gearbox, the next thing you know an "oil thread" would be created on this forum.   

A great reason for not having a transmission.   

Now that's funny . . . and true!  Every m/c forum I've ever been on had at least one oil thread going at any time.  On the H-D forums there were more like 3 or 4, each dumber than the last one.

Your choice of IC oil is apparently like your choice of a religion.    I have no idea why?    Perhaps it is all just a big plot by Big Oil. 

[MrDude_1]

The funniest part is that once you understand a bit of the science behind the oil, instead of "ONE OIL TO RULE THEM ALL"  you can just go "anything in this group is fine for X application"... and thats that. You never need to look at an oil thread again.

So, just dedicate 2 years of your life to the subject, and you never have to read a forum thread about it. Problem solved.

[hubert]

- Riders like doing stuff when they ride and shifting is one of them
- They are much happier with an automatic transmission

- 25 years ago, riders wanted to "kick" start their bike, electric gadgets are too girly
- Now they all have electric starter

- sure, ABS is for non-riders only
- sure, really?

Other domain, but same "male self-esteem" issue

- 25 years ago, the pro photographers said "autofocus is for tourists, true photographers want to decide with their own hand how to set the sharpness"
- Now the pros' are comparing the AF performance of high-end cameras, and always moaning when the AF is not as perfect and fast as they expect...