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Thalass
19 February 2011, 1944
Hey folks. I'm just taking lessons to get my bike license (as the first stage of my EV project haha), and i've just started to get good at riding slowly - that is slipping the clutch, riding the back brake, and keeping the revs up. I'm told when you do this the flywheel spins faster, and it provides the gyroscopic stability when your wheels aren't moving fast enough.

So i was wondering how an electric bike goes, when it's direct drive and most likely doesn't have a flywheel at all. Even at a 10-1 sprocket ratio i don't think an electric motor would have the angular momentum to keep you upright. But i don't know.

So how do you guys go at slow speeds?

magicsmoke
19 February 2011, 2116
Hi Thalass, I'm sure the flywheel has some effect on slow speed stability, but I can also assure you that it's bugger all :)
How slow can you ride a bicycle?
Basically, you keep the revs up so you don't stall the bike or at least suffer the chug chugging effect.
I wouldn't think too much about this stuff at this stage, just concentrate on being safe and memorising the question hoops that you have to jump through to pass your test.
Good luck with the lessons.

Rob

ZoomSmith
19 February 2011, 2152
It's infinitely easier to do low speed maneuvers with my EV since I don't have to slip the clutch to do so.
Also the lack of ICE vibration gives me the feeling of more control at low speeds.

teddillard
20 February 2011, 0404
Infinitely easier as long as you're not looking to grab a handful of clutch to stop power... :D The only time I've had the slightest problem with the bike was trying to thread through a narrow slot in my driveway. I lost my balance, the usual backward fall move which twists the throttle more, and a futile grab for a non-existent clutch. It's OK, there's a bald patch on the driveway asphalt and the bruises have healed...

I know Dave is planning to rig a cutoff/regen switch to a "clutch" lever, I'd seriously consider at least a kill switch lever for a street build now.

I also am seriously considering a clutch. Not a transmission, but a clutch. But then I wake up. (ducks, runs away...)

jazclrint
20 February 2011, 1234
I know on the 180 degree crank on my VFR at idle you can actually see bike kind of rock side to side a bit. And in interviews AMA campion Arron Gobert, and BrammoBriam say that elmotos feel lighter (Brian said about 100lbs lighter) when riding due to the lack of a reciprocating motor. This effect is exactly what Micheal Czysz was trying to negate in his MotoGP bikes he designed and built. My point is that I from all this I believe that the effects of a reciprocating motor are probably much greater than we realize. So, maybe reving the ICE motor at low speed turns is just as much about not stalling it, as it is about spinning the engine up enough to make the effects of the reciprocating parts more constant, predictable, and manageable. So you eliminate all that crap when you go to an EV. But I'm just thinking about this stuff in my head, have yet to swing a leg over an EV, and could very well be full of crap. I would still think though, that dragging the brake and applying constant power, is still they way to go when doing a tight U-turn, just to keep the suspension settled and constant.

Richard230
20 February 2011, 1555
I agree that using the brake while riding an IC bike, while on a bit of throttle, is a great way to navigate tight up-hill turns. However, I don't think that technique would work with an electric bike outfitted for regenerative braking. The regen would probably come on and kill forward motion.

jazclrint
20 February 2011, 1809
See, didn't even think of that. That made me think of something else thought. If you have a bit of throttle on, and some brake, which takes priority in the logic in the controller, the regen or the throttle?

podolefsky
20 February 2011, 1828
Hey Thalass,

I took my motorcycle driving test on my electric bike. I think the size and weight of the bike probably makes a bigger difference than electric vs ICE (although it makes sense that electric would be easier because you don't have to deal with the clutch).

My bike is based on a GSXR 1100, and it has a 4" extended swingarm to boot. At high speed it's stable as hell, but below 10 mph, it's a handful. I practiced and practiced and got good enough to pass the test...barely. If I was on my scooter, or something like a CB250, it would have been a breeze.

Richard230
20 February 2011, 1836
The nice thing about a clutch is that you can feather it at low speeds to finely control the amount of power delivered to the rear wheel. With a direct-drive EV you get whatever the controller programming allows at small throttle openings. What power the controller wants to provide when the throttle is cracked may not be what you want when performing the figure-8 in the DMV parking lot for the "skills" portion of your California driving test.

Thalass
20 February 2011, 1921
Thanks guys. I won't have my EV before my test, but at least i know it won't be anything to worry about when i do have it. My major problem is the 250cc restriction here. For a year after i get my license i can't have a bike larger than 250cc, which makes chosing a bike for the conversion tricky - i can't wait another year! haha. But i'll see how it goes.

Thanks!

DaveAK
20 February 2011, 2024
See, didn't even think of that. That made me think of something else thought. If you have a bit of throttle on, and some brake, which takes priority in the logic in the controller, the regen or the throttle?
With my controller setup you can't have regen and throttle at the same time. Can't say how other controllers work, but the Sevcon doesn't allow it.

BaldBruce
20 February 2011, 2045
Regen overrides throttle input in the PM Kelly controllers. This is one of the reasons I plan on using the seperate throttle input to the regen rather than connect to the brake and have a fixed regen. This way I can have both mechanical brake and throttle at the same time. (Smell the burning rubber through the computer connection????) I can also then vary the regen based on condiyions since I don't want much if it's slippery...

podolefsky
20 February 2011, 2143
Thanks guys. I won't have my EV before my test, but at least i know it won't be anything to worry about when i do have it. My major problem is the 250cc restriction here. For a year after i get my license i can't have a bike larger than 250cc, which makes chosing a bike for the conversion tricky - i can't wait another year! haha. But i'll see how it goes.

Thanks!

Man, that is one crappy law. I'm not sure how registration works in CA - they might take into account that your bike is no longer ICE. So even if it was a 750, if it is converted to electric with 25 HP it might be OK. When I registered in CO they just put down "93 GSXR 1100". The woman at the DMV just said "we don't have a spot to put what type of fuel it takes, so you're good to go." But when I took my driving test, they wanted to know how many watts the motor was to figure out the equivalent cc, since there are different tests for different sizes.

Anyway, might check into how they actually register the bike...you might be OK.

electriKAT
21 February 2011, 0908
This is an interesting discussion. I have never really thought about it before. I've been riding for nearly 30 years, and had my license for 20. On a gas bike, if I want to go slower than min comfortable speed in first gear, I just pull the clutch in and drift. Balance takes practice, but it will come. I don't see any reason to feather the clutch, drag the brake, and modulate the throttle; it sounds unnecessarily complicated. Although I may give it a shot the next time I'm on a gas bike, just to see what it feels like. My suggestion, try drifting, and don't over think it.

On an electric bike, I find slow speeds to be easier. When you let off the throttle, you freewheel. And there is no clutch. Just be sensitive to throttle input and you should have very good control.

My $0.02.

Richard230
21 February 2011, 0924
The problem with modern IC bikes that are fuel injected is that they have abrupt on-off throttle response that makes it really tough to go slow. You need to either feather the clutch to ride slower than idle speed, or keep the throttle on while dragging the brake. Either of these riding techniques makes it a lot easier control your motorcycle at slow speed.

In order to perform a tight uphill turn at at slow speed, where if you accidentally close the throttle you might stall, dragging the rear brake is really helpful. I learned this technique while riding up Mt. Hamilton, east of San Jose. That road has a couple of very tight steep right-hand uphill corners near the observatory that you take at around 5 mph, if you want to stay on your side of the road . That is really tough to do while keeping the engine pulling so that it will haul you uphill, yet not go too fast that you blow your line on the curve. If you drag the brake, you can keep the power on, while adjusting your speed with the brake and that will prevent the possibility of a stall because you accidentally cut off the power by closing the throttle.

On level ground, feathering the clutch allows you to go slower than idle speed and keeps the dreaded abrupt on-off throttle transition from upsetting your day - or at least your style.

HighlanderMWC
22 February 2011, 1232
In California the Motorcycle Safety Foundation course takes the place of the DMV skill test (well at least it did in 1994 and I haven't heard anything different since) and you get to do it on their bikes (i think Honda CBR125 when i did it).

I can say that an electric that is set up well is a pleasure to handle at low speed. On my Enertia feathering the throttle works quite well and I have enough sensitivity that I can feel the motor loading.

DaveAK
22 February 2011, 1237
In California the Motorcycle Safety Foundation course takes the place of the DMV skill test (well at least it did in 1994 and I haven't heard anything different since) and you get to do it on their bikes (i think Honda CBR125 when i did it).
Same here in Alaska. Just waiting for the snow to clear then I'll be taking my test. I was just thinking about this this morning and realized I haven't riden a bike in 10years. Looking forward to rectifying that. :)