Motorcycle vs car engine

[redpoint5]

Originally Posted by Frank Lee

That reminds me of another point: motorcycle drivetrains appear to me to be quite lossy. By that I mean, unlike in most cars where the power goes from engine to trans input shaft to output shaft to differential to wheels, bikes usually (always?) employ chains or belts between engine and trans, and after trans too. More chains and belts and shafts and **** means more drivetrain losses.

There are not many other methods more efficient at transferring power than a chain. Chains are more efficient than gears and shafts.

The reason shafts and gears are employed is to reduce maintenance, not to increase efficiency.

I'd be curious to know what other methods of energy transfer are more efficient than a chain.

[Frank Lee]

The reason they stuff their drivetrains full of gears, chains, and belts is packaging. It's not more efficient to stick a jackshaft in there if it can be done without it.

[drmiller100]

Originally Posted by Frank Lee

Power transmission efficiency drops at least 1% with every chain, belt, or gear mesh between the crank and the wheel(s) right?

nope.

shafts are VERY efficient. Constant Velocity joints are VERY efficient. Non O-Ring chains are VERY efficient, as are O-Ring chains.

In every racing class where it is legal, motorcycles ALWAYS run a chain. Bicycles use chains for a reason.

Gears are next on the efficient list.

Belts somewhere lower. Belts lose energy to hysteresis effects. Plus they are not as strong as chains, and are much more picky for alignment.

Bearings all take a tiny bit of energy to turn.

Something which is relatively inefficient is a ring and pinion. Pretty hard to make a final drive without a ring and pinion, although more and more FWD cars are doing it.

I have read a ring and pinion can be as bad as 13 percent inefficient. Seems high to me.

[dcb]

Originally Posted by drmiller100

nope.

I believe Franks statement was technically correct. I'm not sure what you are saying "nope" to unless you just like being disagreeable.

[Frank Lee]

Originally Posted by miller

nope

Oh yes it does.

Chains are not better than 99% efficient.

Belts can be 97-99% efficient, depending on if they're Vee, synchronous, or what have you.

CV joints lose a bit of power too. I think it's less than 1%, but it's still a loss, just like bearings are. Just like the mere fact that spinning a shaft takes power. If spinning a shaft DIDN'T take power, it would just sit there and spin with no power input right?

I don't think you are getting what I'm talking about. AS NOTED on a car the power goes from end of crankshaft to trans input shaft. On a bike it does not. It goes through a chain or belt first. STRIKE ONE! That's a 1% loss the car does NOT have. Same thing on the other end of the transmission- STRIKE TWO! So by the time the power gets to the output shaft on a bike, it will have lost 2-3% or maybe more vs if it had an automotive layout.

[dcb]

yes, a chain primary reduction sounds sort of harley-ish but on most of the exploded bike diagrams I've seen there is a small gear on the crank and a large gear on the clutch basket or something.

from there both cars and bikes suffer from constant mesh transmissions (for packaging) as opposed to some configuration that only meshes the gear in use.

then most every bike I have had takes the output to a chain to the wheel, and a car would use a shaft and hypoid differential (rwd) or a reduction gear differential (fwd)

Best numbers I've seen for a chain were %98.

[Frank Lee]

I did mention the Gold Wing; it has a chain tween engine and trans, then there's the transmission gearsets, shafts, and bearings; another chain from trans output to direction-changing gearset; then the drive shaft with the joints and bearings; then the final drive gears. The system efficiency for my GL1100 must purely SUCK.

[drmiller100]

Originally Posted by Frank Lee

Oh yes it does.

.

actually, if you start spinning a shaft, it will continue spinning unless an external force acts upon it. It takes no horsepower, in and of itself, to spin that shaft.

Further, you don't get to just say "each thing in the middle takes one percent".

[dcb]

Originally Posted by drmiller100

Further, you don't get to just say "each thing in the middle takes one percent".

dude, he didn't say that.

[Frank Lee]

Ah, I can see this is going nowhere. Sweet dreams.