| Author | Message | ||
     Jaimec |
Some time ago we had a long debate here on whether or not electric motorcycles NEEDED a transmission with Blake on the "Pro" side and everybody else being skeptical. This article seems to imply that the skeptics were right... Brammo wasted both weight and battery space for a transmission the bike DOESN'T need: http://www.motorcycledaily.com/2013/02/md-double-t ake-2013-brammo-empulse-r/ | ||
| Reepicheep |
I was on the "pro" side as well. I think a sporting electric bike *does* need a transmission. A scooter doesn't though. I'll post this before I read the article so I am right or wrong fair and square. | ||
| Reepicheep |
Meh. Not a verdict one way or the other. The first rider said it should have two gears (city and highway) but was unconvinced he needed a clutch. The second rider was clearly more technically astute, and he got the reason for both the transmission and the clutch... and correctly observed that the only reason they weren't useful is because there was a computer nanny stopping his attempts to wheelie and burn out. This was the correct observation. And not a suprise, if you listen to the Motorcyclist Radio interview by Steve Natt (who has an irrational fear of Sara Palin and seems driven to be rude as a result, but who also rides an 1125CR and seems to be a nice guy in other respects) with the president of Brammo, the bike is pretty much designed for "void your warranty" post purchase upgrades. Out of the box it comes buttoned down and with all the blade guards in place. If you want to make this the hooligan bike it begs to be, give your warranty a goodbye kiss, and start hacking. You will then get what the transmission and liquid cooled motor promise, wheelies, smoking back tires, and a genuine motorcycle experience. If their dual sport version was $10k, I would be sorely tempted to buy one, and mod it quickly. It would make a stupid fun commuter bike. | ||
| Teeps |
Reepicheep Posted on Monday, February 18, 2013 You will then get what the transmission and liquid cooled motor promise, wheelies, smoking back tires, and a genuine motorcycle experience. The mistake is expecting "a genuine motorcycle experience" which it's never going to be. If your expectations are that which an internal combustion motorcycle provides. The same can be said of the auto industry with CVT transmissions. Honda spent millions trying to make the CVT experience like their automatic transmission experience, which was never realized. For the electric vehicle to take root. The end user must have no prejudice or expectation, when taking the bars or the wheel. Thus accepting the EV for what it is; different... | ||
| Sifo |
There is an apparently difficult concept that you really need to understand with an electric motor. They run most efficiently near their peak RPM. This is pretty much the opposite that we are accustomed to with IC engines. This means that shifting into a higher gear once you reach your cruise speed with an EV will hurt your economy. Combine this with producing max torque pretty much at zero RPM and it becomes apparent that a gear box just isn't a requirement for the market that an electric bike will be targeting. You can gear it to give good results from 0 to 70 mph without any need for the weight, expense, and complexity of a clutch and gearbox. Direct drive is all you need. | ||
| Reepicheep |
That's probably why I am leaning toward the dual sport version (with a transmission). Geared right, the KLR-250 I had (which probably had 20 HP on a good day, and it hadn't had good days for at least a decade before I bought it) was still a ton of fun for around town up to 55mph highway playing. The Brammo dual sport would be better than that. | ||
| Natexlh1000 |
Authentic motorcycle experience:  | ||
| Jaimec |
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| Nik |
The direct drive bikes currently on the market come with electronic nannies too. They all limit the amount of amps the motor can draw at low rpms which kills the torque and low end acceleration. Adding a transmission doesn't change that. But beef up and cool the motor effectively and crank up the juice... | ||
| Sifo |
But beef up and cool the motor effectively and crank up the juice... Then watch as the next weak link gives up it's magic smoke. | ||
| Britchri10 |
Cool the motor = take the weight penalty! Chris C | ||
| Kenm123t |
forget the transmissions IGBTs are where its at | ||
| Ourdee |
Get rid of the gearing and run the motor in the hub/wheel. | ||
| Blake |
>>> You can gear it to give good results from 0 to 70 mph without any need for the weight, expense, and complexity of a clutch and gearbox. Direct drive is all you need. Or you can put a gearbox in it and be able to accelerate to 70 mph in half the time. But who would want that? ME! And every other acceleration junkie out there. Motor is most efficient at high top speed... So then with a gearbox it would be more efficient being able to run at top speed for multiple mph rates. | ||
| Blake |
>>> The direct drive bikes currently on the market come with electronic nannies too. They all limit the amount of amps the motor can draw at low rpms which kills the torque and low end acceleration. Adding a transmission doesn't change that. Sure it does. It puts the motor out of the troubled over-current prone "low end" portion of its operating range, allowing it instead to operate in the mid to high end of its range. | ||
| Blake |
>>> They run most efficiently near their peak RPM. This is pretty much the opposite that we are accustomed to with IC engines. This means that shifting into a higher gear once you reach your cruise speed with an EV will hurt your economy. Your assumption of an overdrive is off base. The gearbox is to provide lower gears to allow more power at lower speeds, not higher gears for lower motor speed at cruise. | ||
| Blake |
In effect, the direct drive version is always stuck in high gear. Low speed acceleration is very weak. Add a gearbox with same top gear drive ratio, and now you have decent acceleration at lower speeds. I doubt I'd buy an ebike with direct drive. A clutch to decouple torque transfer to the rear wheel is also something I'd not want to give up. | ||
| Sifo |
Yes, add a gearbox so that at low speeds you can operate the motor at higher RPM where torque is dropping off. This is IC thinking. Electrics just don't have the same benefits, and when cost and weight are factored in, they just stop making sense for the target market. I probably won't buy one without a gearbox either. Then again, I probably won't buy one with a gearbox. Why spend well over $10K for something that competes with a CBR250r for less than half the price? | ||
| Hybridmomentspass |
I do not see how this article proves that gearboxes on ebikes is a bad/pointless thing. Now Im not an engineer or anything like that, and I wont pretend to be But it seems like a gearbox, as Blake has said, would keep it in its sweet spot for multiple conditions How could that be a bad thing? This article shows how their current setup isn't ideal - hell, people said the same stuff about Buells - clunky shifting and so on. So no different. As the technology improves so will the range, space, and all else. Im not interested in one, I'll stay with a standard ICE bike, like Sifo said, for that money I'd expect a lot more out of a 'sportbike' | ||
| Natexlh1000 |
How many of these bikes use regenerative braking? I would think it would help range a great deal in a city environment. | ||
| Sifo |
But it seems like a gearbox, as Blake has said, would keep it in its sweet spot for multiple conditions How could that be a bad thing? In theory, I can see where a simple hi/low range gear box could be beneficial. No clutch, no shifting while moving. Simple around town/highway selector. That would keep weight and cost down. It's all about range with electrics. More efficiency is fairly critical. Cruising at around town speeds doesn't take much energy though. Even if it's not optimized for 35 MPH, you get good miles per charge because of low drag. To allow the user to select gears will probably have them trying to use it the way they have learned with an IC engine, shifting into high gear to lower RPM thinking better efficiency. This is all wrong for an electric though. You will draw more amps, and create more heat at low RPM. The fix for this will be automatic shifting to keep efficiency high. There's two big problems with that though; Cost and taking a step away from the traditional experience. Bottom line is that an electric bike isn't going to deliver the traditional experience. It's not traditional. Accept it for what it is or reject it. | ||
| Hootowl |
Regen braking would have to be done by the rear wheel, and most of the braking is done up front. It may not be worth the complexity. | ||
| Cityxslicker |
I am liking the electric moto platform for sneaking up on things.... | ||
| Airbozo |
I actually got the chance to ride several Zero Cycles models and the Brammo on the same day. It was odd not having to run through the gears on the Zero Cycles models, but not something you wouldn't get used to. It did sort of remind me of my Honda Scooter, with much better takeoff and max speed. Shifting on the Brammo also felt odd but that was due to lack of an audible RPM indicator (for me). Again, with enough experience it wouldn't be an issue. I do agree with the 2 speed comment though. | ||
| Jaimec |
Instead of regenerative braking, how about recharging when "coasting?" That would provide the simulation of "compression braking" from an ICE and at the same time eliminate that disconcerting feeling that you're coasting on a very heavy bicycle... | ||
| Froggy |
What you describe is exactly what regenerative braking is. It is simply coasting and using the momentum of the vehicle to recharge the battery as it slows down. | ||
| Froggy |
As regenerative braking is nothing more than simply slowing down while in gear, there is no additional complexity, and no reason not to have it. In fact, it would be more complex not to have it, as you would need something like a clutch to disengage and allow you to freewheel instead of coasting. | ||
| Hootowl |
Regenerative braking is done WHILE BRAKING, not while simply off throttle. Electric cars that employ regen braking do not apply the regen/generator "brake" when you get off the throttle. Using it to simulate engine braking could be done, but as it would simply slow you down when you don't necessarily want to slow down, I don't see how this would be a benefit. Engine braking is, in most instances, not desirable. Motorcycle engineers program ECMs to minimize this effect. Why would you want to artificially introduce it? | ||
| Froggy |
But they do. Try it in any electric or hybrid, simply coast down a long hill without using the brakes or giving it any throttle, you will see the battery will regain some power. The electric motor is still spinning, but instead of using power from the battery to propel the vehicle, the wheels are turning the motor and it is acting as a generator.
When you step on the brake on an electric or hybrid vehicle, you are just dialing up the regenerative effect causing more engine braking. This is why EVs and hybrids require less frequent brake pad replacements. The real brakes still get used, just significantly less. | ||
| Hootowl |
Seems Zero does use regenerative braking on at least one of their models. The effect must not be very pronounced. |
