On rear stand tire spins forever w/clutch pulled; must stop by hand...normal?

[CZroe]

I've always detected the rolling resistance significantly increase brefore releasing the clutch when shifting down out of neutral. In other words, neutral is not equal to clutch pulled. I had to pop-start the bike once and, sure enough, it was way to difficult to push up a hill if you tried to do it with the bike in first and the clutch pulled in. Shifting into neutral definately had much less resistance. As far as I know, that's normal. The bike has been serviced several times in the year-plus/10K miles I've owned it and no service people have ever reported a problem. I think I've always had notably bad fuel economy, never breaking 50MPG, but I always attributed that to me being almost 250lbs. Now I think I might have a rolling resistance problem.

So, I finally got my slider spools today and got it lifted up on the rear stand for the first time. I put it in neutral and started up the bike and the tire remained still. I spun it with my hand and it quickly stopped. I pulled in the clutch and shifted down and the tire instantly started spinning at full idle speed while I was still holding the clutch all the way in. It would keep spinning forever unless I stopped it by force, at which point it would remain stopped. From there if I spun it lightly it would stop immediately. If I spun it with force, it would pick back up and keep spinning forever. Clearly, the rolling resistance of the tire at rest combined with a stationary object's tendancy to remain stationary (also called momentum) is enough to overcome the slipping clutch. With rolling momentum and the clutch pulled in fully the transmission still seems to be providing enough assistance to keep the tire moving at full speed... but is the clutch even supposed to be slipping or is it supposed to be fully-disengaged while the clutch is held in? The play on the clutch lever is within spec and the dealer service-people have adjusted it in the past.

So, is it normal for the tire to spin with the clutch fully retracted? How long should the tire continue to spin when you put it in neutral?

[LazinCajun]

As I understand it, the rear tire spinning with the clutch in comes from having a wet clutch, especially with cold oil. The cold oil in the clutch has a high enough viscosity to spin the wheel slightly when it's up on a stand. I don't know if that fully explains everything you're describing or not though.

Edited to add: not trying to be a jerk, but you're talking about inertia and not momentum. I apologize in advance.

[CZroe]

Originally Posted by LazinCajun

As I understand it, the rear tire spinning with the clutch in comes from having a wet clutch, especially with cold oil. The cold oil in the clutch has a high enough viscosity to spin the wheel slightly when it's up on a stand. I don't know if that fully explains everything you're describing or not though.

Edited to add: not trying to be a jerk, but you're talking about inertia and not momentum. I apologize in advance.

Thanks. Now, I wonder if I can get anyone to tell me how long it takes for their tire to stop shen shifted into neutral from 1st gear idle speed. Mine is almost instantaneous so I suspect that I have too much rolling resistance for some reason. It would explain my poor fuel economy. I've seen others suggest that the Ninjette could get insane economy using "pulse and glide" hyper-miling technique, but the Ninjette slows so fast on me that it would never work!

When I first learned the definition of momentum in 3rd grade (when discussing Sir Isaac Newton), that is how they described it. I know they also call it inertia, but the Bob Jones University science book called it "momentum." FWIW, the intro of "Portal," a first-person physics puzzle game, uses "momentum" incorrectly.

[LazinCajun]

Hm, the easiest thing I can think would be to make sure your chain is cleaned/lubed. I've been lazy about getting a rearstand, so I can't help you out there.

On momentum vs. inertia: I'm a big physics nerd. 99.99% of people wouldn't worry about it, and 100% know what you mean. Feel free to throw things at me and call me four eyes. Bonus nerdism: Galileo was the first Western scientist to write about the idea, before Isaac was even born! Ok, I should stop talking before I get completely shunned

[Jerry]

Originally Posted by CZroe

Thanks. Now, I wonder if I can get anyone to tell me how long it takes for their tire to stop shen shifted into neutral from 1st gear idle speed. Mine is almost instantaneous so I suspect that I have too much rolling resistance for some reason.

This could be attributed to a few things, and comparing to idle speed would need to be a little more specific (e.g. my bike idles at 2k, yours at 1.3k..)

Dirty, or worn bearings
Rear brake dragging
Chain too tight, too loose, dirty, or misaligned.
Some sort of sprocket problem
Rear axle over torqued (maybe, not sure on that)
Really unbalanced tire (really, really unbalanced)
The high frictional resistance of momentum battling inertia
Remember, it's not ratcheted like a bicycle tire, even in neutral, there's a lot of stuff involved.

I'd start by checking out the chain, maybe post a vid clip to show how fast its stopping. It may be normal.

[Cedilla]

I would imagine that as long as the wheel does not take much force to spin it with your hand it should be alright, but im just speculating.

[smcbride11]

Mine has a little bit of drive on the stand as well - I assumed it was normal (even though it was weird) because I don't see any other issues.

As far as mileage and engine braking... I'm never in 1st unless I'm stopped. Same as in my Jeep, I find that 1st is low enough that the engine applies a ton of braking effect - so I end up always being in 2nd once rolling, even if I'm moving at less than parking lot speeds. I end up with 60+ mpg regularly in city traffic, so I suspect it's just different use of gears and not a systemic issue. In the Jeep I'll even stick with 2nd in stop and go traffic, but I haven't done so on the bike - just something about the 1 down 5 up pattern makes it feel odd to be in 2nd at a full stop.

[Cedilla]

With the bike, I can take off in 1st, 2nd, and 3rd, but in my car, I can take off in 2nd, but it requires a lot of slipping the clutch.

[CZroe]

Originally Posted by LazinCajun

Hm, the easiest thing I can think would be to make sure your chain is cleaned/lubed. I've been lazy about getting a rearstand, so I can't help you out there.

On momentum vs. inertia: I'm a big physics nerd. 99.99% of people wouldn't worry about it, and 100% know what you mean. Feel free to throw things at me and call me four eyes. Bonus nerdism: Galileo was the first Western scientist to write about the idea, before Isaac was even born! Ok, I should stop talking before I get completely shunned

Quantum Physics: The Brady Bunch Perspective

Originally Posted by Jerry

This could be attributed to a few things, and comparing to idle speed would need to be a little more specific (e.g. my bike idles at 2k, yours at 1.3k..)

Properly adjusted, an EX250J should idle around 1.8K. It's the only point of reference I can measure.

Originally Posted by Jerry

Dirty, or worn bearings
Rear brake dragging
Chain too tight, too loose, dirty, or misaligned.
Some sort of sprocket problem
Rear axle over torqued (maybe, not sure on that)
Really unbalanced tire (really, really unbalanced)
The high frictional resistance of momentum battling inertia
Remember, it's not ratcheted like a bicycle tire, even in neutral, there's a lot of stuff involved.

Like every other I've seen, my brakes are touching the disc. How can I tell if it's enough to be considered "dragging?"

Originally Posted by Jerry

I'd start by checking out the chain, maybe post a vid clip to show how fast its stopping. It may be normal.

I intend to just as soon as I get my phone jailbroken again (not enough time to back it up first). Thanks!

Originally Posted by Cedilla

I would imagine that as long as the wheel does not take much force to spin it with your hand it should be alright, but im just speculating.

I do have to give it a good push to get it to spin and it doesn't seem to spin freely. I have no idea how much force is too much.

Originally Posted by smcbride11

Mine has a little bit of drive on the stand as well - I assumed it was normal (even though it was weird) because I don't see any other issues.

As far as mileage and engine braking... I'm never in 1st unless I'm stopped. Same as in my Jeep, I find that 1st is low enough that the engine applies a ton of braking effect - so I end up always being in 2nd once rolling, even if I'm moving at less than parking lot speeds. I end up with 60+ mpg regularly in city traffic, so I suspect it's just different use of gears and not a systemic issue. In the Jeep I'll even stick with 2nd in stop and go traffic, but I haven't done so on the bike - just something about the 1 down 5 up pattern makes it feel odd to be in 2nd at a full stop.

Actually, that makes me even more suspicious and less likely to consider it simply "different use of gears." You see, I, too, have strived for better MPG and gone through a few tanks taking it easy like that. I still have yet to exceed 50MPG.

[smcbride11]

Originally Posted by CZroe

Actually, that makes me even more suspicious and less likely to consider it simply "different use of gears." You see, I, too, have strived for better MPG and gone through a few tanks taking it easy like that. I still have yet to exceed 50MPG.

Depends on your riding profile... With heavy highway use, I'm right around 50 as well. When I spend the whole tank commuting, it's more like 60-65.

The roads around Miramar are also much faster than my 25 mph speed limit roads - my commute usually has me in 2nd or 3rd at 6 or 7k rpm.

[CZroe]

Originally Posted by smcbride11

Depends on your riding profile... With heavy highway use, I'm right around 50 as well. When I spend the whole tank commuting, it's more like 60-65.

The roads around Miramar are also much faster than my 25 mph speed limit roads - my commute usually has me in 2nd or 3rd at 6 or 7k rpm.

My commute is only 10mins (sometimes less) and is mostly 35-45MPH. I spend more time warming up than driving! I know that is when it is at its least efficient. A neighbor even complained about the fumes!

[kkim]

Originally Posted by CZroe

My commute is only 10mins (sometimes less) and is mostly 35-45MPH. I spend more time warming up than driving! I know that is when it is at its least efficient. A neighbor even complained about the fumes!

That alone may be the cause of your poor gas mileage.

As far as the wheel that keeps on turning when pulling in the clutch... normal.

[backinthesaddleagain]

Originally Posted by CZroe

My commute is only 10mins (sometimes less) and is mostly 35-45MPH. I spend more time warming up than driving! I know that is when it is at its least efficient. A neighbor even complained about the fumes!

Maybe drop the ninja somewhere else for the day and borrow a straight piped HD. Then see if the ninja fumes bother him the next day.