ElectricMotorcycleForum.com
General Category => General Discussion => Topic started by: tommydog on March 12, 2023, 02:39:51 AM
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Do you think we will ever see a long range adventure bike with shaft drive? I am thinking something with decent specs like the Energica Experia? Granted shafts are not as efficient as chains, but it would be a maintenance dream. Plus if it had a 20 kWh battery, we would still see decent range.
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Do you think we will ever see a long range adventure bike with shaft drive? I am thinking something with decent specs like the Energica Experia? Granted shafts are not as efficient as chains, but it would be a maintenance dream. Plus if it had a 20 kWh battery, we would still see decent range.
I doubt it because it is a very bad idea on an electric motorcycle. There is probably no better way to reduce power and range instantly than by using a driveshaft. Belts and chains are much more efficient. On an ICE touring bike, a driveshaft is a great idea. Still reduces power and MPG. It would be a stupid idea on a race bike or an electric bike, IMAO. A driveshaft also increases the bike's weight by a few lbs.
Chain maintenance is not that big of a deal. Until you have to adjust it without a centerstand. I don't have the guts to try to use one of those stupid wheel lift thingies that lift the wheel up on a heavy bike unless there are two people. I wish those were never invented so all bikes would still have center stands.
-Don- Reno, NV
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What if the motor was put in the hub of the wheel instead. No shaft needed, it just instead of spinning in the center, the center was stationary and the outside /wheel spun instead? Balancing might be a bitch but it'd lower cog quite a bit, possibly making the bike more stable. Potentially doing away with a gear train, and chain, lowering weight, and / or putting more room for battery capacity. Just run a few cables from power bank to motor. Slip ring rig might work, as long as you are not messing with commutation there are ways to get the power where needed w/o standard carbon brushes.
or just put some plastic sheets around it, one huge ass leaf blower and make it a huge hovercraft ;D
Aaron
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Electric motors make such STUPID amounts of torque I really don't think a shaft drive would make that much difference to the average consumer.
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What if the motor was put in the hub of the wheel instead.
That has been done. Check this video out:
https://www.youtube.com/watch?v=a7oTg6XJsnk
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That has been done. Check this video out:
I always thought that was a great idea. No belt, chain or shaft. But who will be able to change the tires on that?
-Don- Reno, NV
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Electric motors make such STUPID amounts of torque I really don't think a shaft drive would make that much difference to the average consumer.
The power will suffer (the acceleration), not the torque.
-Don- Reno, NV
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Electric motors make such STUPID amounts of torque I really don't think a shaft drive would make that much difference to the average consumer.
The power will suffer (the acceleration), not the torque.
Not enough to make a difference to the typical rider though. Believe it or not, not EVERYONE needs to be the fastest kid on the block. Being able to out-accelerate the majority of automobiles out there is enough,.
-Don- Reno, NV
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Not enough to make a difference to the typical rider though. Believe it or not, not EVERYONE needs to be the fastest kid on the block. Being able to out-accelerate the majority of automobiles out there is enough,.
I agree, I wouldn't care much about that. But perhaps with the difference in range, Even a mile is a lot of reduced range when you have to walk that last mile with the bike!
But perhaps the real issue is the cycle companies like to have better specs than their competitors.
-Don- Reno, NV
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I don't see how changing the tire would be that much worse. Just use the machine on it, but carefully., It does not seem like there is a lot of hardware holding that wheel in so the entire thing should pop out. now granted it may weigh 300 lbs but that's really no different than a truck tire id think.
or maybe they sell them as a plug and play, you bring the old worn out one to the shop, they give you a new / refurb one to put back on, tighten the 4 bolts and you are back in business? Kind of similar to a rethread or capping? from there they take the old to the factory where they are set up to change / inspect, fix and resell
Aaron
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I don't see how changing the tire would be that much worse. Just use the machine on it, but carefully.
Although that would be a major drawback if touring in a remote part of the world and trying to change it by the side of the road. Out of interest do you like the design? Do you ever see a major manufacturer adopting it?
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I don't see how changing the tire would be that much worse. Just use the machine on it, but carefully., It does not seem like there is a lot of hardware holding that wheel in so the entire thing should pop out. now granted it may weigh 300 lbs but that's really no different than a truck tire id think.
or maybe they sell them as a plug and play, you bring the old worn out one to the shop, they give you a new / refurb one to put back on, tighten the 4 bolts and you are back in business? Kind of similar to a rethread or capping? from there they take the old to the factory where they are set up to change / inspect, fix and resell
Aaron
How are they going to balance such a tire when there is no axle? But I think I like the idea and I hope it works and becomes very commonly used. If the design becomes common, there will be many ways to deal with the once oddness of it.
-Don- Reno, NV
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Aaron
How are they going to balance such a tire when there is no axle?
-Don- Reno, NV
Easy, they can put it on a spindle / bobbin and spin it, if it's off balance it'll tip and they'll see where and then you can shim it. it may even be factory balanced with just a little tappity tap around the edges as the tire wears. given the drive force is on the edge of it and it's not 'centering' around an axis like a regular tire, that might not be as big an issue, I honestly don't know. We have balanced huge rotors in our generators that weigh 200 k lbs down to half an ounce, so yes, the tech amazingly IS there.
Aaron
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No regular bike shop would be able to balance that thing, I'd imagine most wouldn't even attempt to put a tyre on it. A regular old hub motor using an axle like a normal wheel makes more sense. One of the issues with hub motors is high unsprung mass, the second is you have no control over gearing to vary the torque (unless it's a geared motor, but that's not an easy thing for a consumer to play around with).
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It's pretty much direct drive, it basically grabs the wheel on a corner where it goes under the coil and just like you'd grab a bicycle tire and give it a spin, same principle, only with a lot more power. But, to keep you standard wheel guys happy Im sure they can put some spinners in the hole for you :D Maybe even have a little speaker to go Brrr BRRRRrrr so you can pretend you are still on your ICE bike :P
Aaron
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Yeah direct drive isn't always best, otherwise every Zero would be geared 1:1 and Energicas wouldn't have their gearboxes.
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Although that would be a major drawback if touring in a remote part of the world and trying to change it by the side of the road.
Have you tried to do that in the last few years with the new tires? I don't think it is even possible these days. It is actually easier to change a truck tire than a motorcycle tire on the side of the road when you have the proper hand tools.
I tried to change a tire (which I have done countless times in the distant past) on my little Suzuki DR200SE with large, long tire irons. I gave up and brought the wheel to a shop for them to change it with their shop tools. Took them a few minutes or so. And even on this bike, I have changed the tires before. The tires have changed in the last few years. Much more difficult to remove. I couldn't even do it.
-Don- Reno, NV
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I keep reading this nonsense about shaft drive efficiency being ludicrously low and it's repeated about on the internet, the same set of figures, parrot-like, but I have a feeling it's ... bullshit. Or BMWs would be slow as hell (they are not), and their shaft housings would be rather hot to the touch after a 100mph blast down the motorway (they are not, they barely get warm). I've had 5 shaft-drive BMWs. They were all noted for being surprisingly fuel efficient.
I bet the losses are large just in relative terms to a chain or belt. That is if a chain is losing 3% to friction then ooh maybe the shaft loses twice as much! Or ... 6%. I'd still take the shaft drive even if it meant I could only go 94 miles instead of 97.
Cas :)
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I keep reading this nonsense about shaft drive efficiency being ludicrously low and it's repeated about on the internet, the same set of figures, parrot-like, but I have a feeling it's ... bullshit. Or BMWs would be slow as hell (they are not), and their shaft housings would be rather hot to the touch after a 100mph blast down the motorway (they are not, they barely get warm). I've had 5 shaft-drive BMWs. They were all noted for being surprisingly fuel efficient.
I bet the losses are large just in relative terms to a chain or belt. That is if a chain is losing 3% to friction then ooh maybe the shaft loses twice as much! Or ... 6%. I'd still take the shaft drive even if it meant I could only go 94 miles instead of 97.
Cas :)
I think you will find BMW's fastest bikes to be using a chain drive. The ICE bikes for touring are the ones with the shafts. FWIW, my 1,000 lbs Harley uses a belt and usually gets better than 50 MPG. However, my TTSE is shaft driven and gets around the same MPG but it is a lot lighter.
My MotoGuzzi only gets around 42 MPG, Shaft drive but also uses TBI instead of the true EFI. Kinda difficult to compare. But I heard about the power loss of driveshafts long before the internet existed. BTW, shaft drives can give some real serious problems, they are not 100% reliable either and when they give problems, there's no fixing on the side of the road.
Power loss in a motorcycle chain is around 3%. A drive belt is about 10%. Power loss of a motorcycle drive shaft is often above 20%.
The one I cannot figure out is why the big difference between the chain and belt.
-Don- Reno, NV
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With bicycles the difference in efficiency is very minimal (a percent or two) and mainly comes from the higher tension of the belt, and the difference is greatest at lower power levels for some reason. A motorcycle belt is at an even higher tension so that's probably why. It could also be due to the generally lower gearing than a bicycle, you've got many more teeth engaged on the larger rear sprocket with a belt where as with a chain drive not every roller on the sprocket is actually applying force.
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There are two main reasons the shaft is not preferred and that is cost and weight.
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The one I cannot figure out is why the big difference between the chain and belt.
-Don- Reno, NV
I would say friction losses but THAT much you'd think it'd burn up the belt in short order. Maybe, because it's friction drive, the metal holding the belt at either end is greater to transfer that friction...without burning up the belt, and the extra weight of all that metal spinning round is eating efficiency... but 3 percent?? You'd probably lose a bit of energy at the start up due to slippage but what overall amount? it can't be THAT terrible.
Is the 3 percent .vs. 6 percent a stat that is still valid with today's tech, or is it one of those things where they figured it out in 1953 and just ran with it to this day and nobody every questioned it because the 'experts' said it is that??
Aaron
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You would make far more impact on range by designing a proper fairing in a wind tunnel than you would with ANY final drive system.
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There are two main reasons the shaft is not preferred and that is cost and weight.
How about chasis jacking? apply power rear swingarm pivots up, do a downshift swingarm squats. Or use something like BMW paralever set up.
The shaft itself probably isn't where the losses are it is in the 90 degree turns and the reduction gearing in those turns,
When you have to buy chain and sprockets retail the shaft most likely is more economical for the user in the long term.
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I think you will find BMW's fastest bikes to be using a chain drive.
Tell that to my K1300S!
My GSes regularly got over 55mpg (UKmpg too - which I think is about the equivalent of 45 USmpg) and that simply doesn't strike me as inefficient as it's about the same as most bikes get when ridden at around the same speeds. If 20% of the energy is being lost by the shaft then it's being lost as heat, and if we're doing 70mph then we need about 11kW to reach the rear wheel, and you're saying that's only 80% of the energy output by the gearbox output shaft? So there's another 2.5kW of waste heat blasting out of the shaft drive? There's no cooling whatsoever - it'd be red hot after a few miles!
The one I cannot figure out is why the big difference between the chain and belt.
Because, once again ... it is probably not true. Some internet nerd will have quoted some figure years ago and it'll have been Googled and parroted ever since. Here's the reality: https://www.cyclingabout.com/belt-drivetrain-efficiency-lab-testing/
Cas :)