PMW Shocker

[Sheriff Jon]

I don't have any specs on this, but here is a pic just released of the upcomming PMW Shocker electric dirt bike with front ane rear CIDLI suspension.

[PaulM]

Love to see a picture of the other side . . .

The single sided front end has been done before (Bimota Tesi, Yamaha GTS1000 come to mind) but it has never stuck around. I wonder what these guys have done different, or are they just trying to be different?

[Sheriff Jon]

Love to see a picture of the other side . . .

The single sided front end has been done before (Bimota Tesi, Yamaha GTS1000 come to mind) but it has never stuck around. I wonder what these guys have done different, or are they just trying to be different?

The company (PMW) has used their patented CIDLI (Cantilevered Independent Dynamic Linkless Indispension) suspension on a number of their GoPed scooter models with great sucess. GoPed is moving more toward Electric power these days, and I guess they wanted to branch out by using the CIDLI concept on a larger motorcycle. The Patmont family are avid off-road motorcyclists and have done extensive testing using more conventional gas powered bikes. It will be interesting to see just how well this design and an electric off-roader work in the real world.

[PatmontS]

Thanks Sheriff,

Here's a few interesting specs about this prototype;

PMW "Shocker" Tri Sport Electric Motorcycle... Street, Off Road, Free Style

198 lb wet (less than a racing 125cc 2 stroke)
0 mph torque approx equivalent to a 400cc 4 stroke
13.5" suspension travel front and rear
Dynamic anti dive braking.
2.3 KWh Lithium-polymer
78V nominal @ 300 amp/10 sec peak output, 250 amp continuous.
Sealed DC brushless dual axial gap motor w/94% efficiency @ 3000rpm/91% @ 6000rpm
Motor serves as throttle controlled regen rear wheel brake.
Sprocket ratio set for 60 MPH.
Not including chain and controls, 6 moving parts (two of those are the wheels).
With freestyle wireless throttle installed, capable of bar spins and tail whips.

[Toshi]

Here's a few interesting specs about this prototype;

PMW "Shocker" Tri Sport Electric Motorcycle... Street, Off Road, Free Style

2.3 KWh Lithium-polymer
78V nominal @ 300 amp/10 sec peak output, 250 amp continuous.

this means they're drawing 10C. yikes.

[PaulM]

Love to see a picture of the other side . . .

The single sided front end has been done before (Bimota Tesi, Yamaha GTS1000 come to mind) but it has never stuck around. I wonder what these guys have done different, or are they just trying to be different?

The company (PMW) has used their patented CIDLI (Cantilevered Independent Dynamic Linkless Indispension) suspension on a number of their GoPed scooter models with great sucess. GoPed is moving more toward Electric power these days, and I guess they wanted to branch out by using the CIDLI concept on a larger motorcycle. The Patmont family are avid off-road motorcyclists and have done extensive testing using more conventional gas powered bikes. It will be interesting to see just how well this design and an electric off-roader work in the real world.

It will be interesting indeed. It appears to be a leading swingarm with some kind of torsion spring in the pivot. From here

With a conventional fork, the wheel moves up and back, "away" from the bump. With this design, the wheel moves up and forwards initially, into the bump. I think this would result in a very harsh ride, but I could be wrong. I can see where the anti-dive during braking comes from though, the braking torque will tend to rotate the swingarm down.

[Sheriff Jon]

[It will be interesting indeed. It appears to be a leading swingarm with some kind of torsion spring in the pivot. From here

With a conventional fork, the wheel moves up and back, "away" from the bump. With this design, the wheel moves up and forwards initially, into the bump. I think this would result in a very harsh ride, but I could be wrong. I can see where the anti-dive during braking comes from though, the braking torque will tend to rotate the swingarm down.

When GoPed first released pictures of the Trail Ripper (model pictured above) it was recieved with mixed reviews because it just looked so strange. But after bringing it out to a few off road races and seeing it compete and win against other scooters with more comventional front forks and rear swing arms on some very large jumps, the reception changed

It is a very simple if not old and tried design that has been use in trailers for years. It is simply four round elatomer tubes inside of a large stationary square metal tube. Then a smaller square tube that is part of the arm that is attached to the wheel is inside of the 4 elastomers. As the wheel moves up and down the small square tube pushes against the 4 elastomers and giving it the progressive dampening.

I have the same design but with slightly less travel on my GoPed Hoverboard (electric scooter) At first the steering is a bit off putting as it feels like the front wheel is trying to fold in on itself. But that sensation quickly disapaits and the suspension just works. In fact it works so well you don't notice it working unless you hit something signifigant, and then your glad you have such suspension.

[liveforphysics]

I think you mean, progressive spring rate, not progressive dampening.

Single sided swingarms were first done by Elf racing for a superbike endurance race. They found they could make up for the extra weight and worse rigidity by saving 45seconds per tire change over the other bikes. Since then, other teams also made single side designs for races with in-race tire swaps. In races with no tire changes, they run bikes with dual sided swingarms. For any and every application that doesn't require in-race tire changes, it's always the inferior design choice, but sometimes still done for marketing products to trendy non-technical motorcycle folk, and that's why you occasionally see it.

The single swing arm inherently will have more weight, more mass, less strength, and either higher bearing loading or additional friction from larger diameter bearings (if they take the giant axel approach rather than the dual conical bearing approach).

As far as a fork that has to move forward to have the suspension function, AND is one sided... Umm... I complain about flex when i race a dirtbike that uses strong conventional forks rather than upside-down forks... Front end flex, and variable steering geoemetry would be a nightmare. When you enter a corner hot, and you start late braking, you NEED the front to drop as you are leaning the bike in to set the corner. It lowers the COG at the time you need it lowered most. Having something that trys to stand up, and resist the function of suspension during the most critical time of brakeing to setup a turn...

I'm guessing this will be marketed to the scooter crowd rather than dirtbike riders.

[Sheriff Jon]

I think you mean, progressive spring rate, not progressive dampening.


I'm guessing this will be marketed to the scooter crowd rather than dirtbike riders.

I admittedly may have used the incorrect terminology, as I am not anywhere as experienced as you are about such matters. And I rather doubt that PMW will target the "scooter crowd' as most of them could not afford the cost of a quality dirt bike, gas or electric. I have not seen the Shocker yet up close and personal, but from the picture I do not think it is anywhere as much of a toy as you may assume.

[Miles]

Single sided swingarms were first done by Elf racing for a superbike endurance race.

http://en.wikipedia.org/wiki/Single-sided_swingarm

http://en.wikipedia.org/wiki/Moto_Guzzi#First_rear_swingarm_suspension

[liveforphysics]

Miles- You are certianly correct about the rear swingarm. I should have been more specific, I was discussing the front of the bike. I'm not a historian, but I'm pretty certian ELF was the first for this in 1984.
Here is a shot of the front-end. The endurance version was single side (and heavier), the non-endurance version was dual sided (and lighter).


A similar design used a single front arm in the bimota tesi 2D as well, because people the buy italian bikes like gimicks



The bimota 1D was more design influenced rather than marketing influenced, so it wisely used arms on both sides for the obvious strength/weight advantages:




These were done this way to enable a king-pin type steering point internal to the hub, so that the geometery could stay even more fixed than a teliscopic fork. and setup with elaborate linkages and caliper mounting to cancel braking induced forces, rather than make the bike stand up when you brake. When steered from a hub-centric point from an in-hub king-pin, a handleing improvement does happen from the geometry being kept more stable than other designs.

When you go single sided, you do not merely double the stress that each single side would carry in a dual sided setup. You introduce a new set of forces, including axial torque that are not even a part of the stressed members in a dual sided design. When the system is under stress, rigidity increases at the cube of radius in tubing, or at the cube of width in a beam. In a dual sided system, the width from the stressed members is spread far apart, so that a pair of very light pieces can provide a large amount of rigidity. In a single side system, unless you are running a section of thin-wall 4-5" pipe/channel, you end up with a very heavy and flexy system.

The PWM shocker would appear to steer from a conventional head-tube arangement to remove the hub-centric fixed geometry steering advantage. It would appear to not have the linkages to cancel the brakeing torque from lifting the bike under braking. It would appear to have a single piviot arm linkage, which will move the wheel in an arc, creating an always changing geometry as the suspension functions. It would appear to be using some very heavy-duty (aka, heavy) arms to create at least the minimum rigidity needed to be functional (assumption).


Now, this said, I do want to wish this product the best of luck, and I do support anyone building something creative and new. From an engineering perspective, I'm getting more of a "style" influenced vibe than an engineering influenced design. I think/hope it may work out fine for casual riders.

I am definately digging the uses of the factory bike's radiator for the water cooling for the motor. My roomate runs that same screw-on turn signal kit on his enduro converted DRZ400. I thnk it was the very cheapest intigrated turn signal kit he could find on ebay

It would appear to be a maybe mid 2000's yamaha yz250 with the plastics spray painted black, some lightning vinal stickers applied over the top, an ebay turn signal kit fitted. Then of course converted to electric, and fitted with some very unique suspension.

Best Wishes,
-Luke

[Miles]

Miles- You are certianly correct about the rear swingarm. I should have been more specific, I was discussing the front of the bike.

Ah! that makes sense. Thanks, Luke.

[fechter]

Very impressive specs, Steve.

I'd be real interested in hearing more about the motor and controller....

Any estimate of price? I bet it will be a 'Shocker', but you get what you pay for.

[liveforphysics]

Well, unless he starts combing craigslist for all the used YZ250's to convert, he isnt going to have much of a product line.

[PaulM]

If it is a production frame, I wonder how the torque from the suspension units is being transferred?

I also wonder how the wheel hubs have been modified to only be supported on one side. A stock axle would snap or bend in short order . . .

Too many questions, not enough answers!

[Sheriff Jon]

Very impressive specs, Steve.

I'd be real interested in hearing more about the motor and controller....

Any estimate of price? I bet it will be a 'Shocker', but you get what you pay for.

I know that I can't speak 'for' Steve, but I thank you for the kind words fecher and having an open mind about the possibilities. "It would appear" that there are some in here who are not quite so.....open minded.

[Lapwing]

The suspension reminds me of the independent sprung rubber torsion type I had on the horse box I owned. Basically a square tube about 2 " with a second solid square bar somewhat smaller at 45 degrees inside. The resulting triangular spaces were filled with a rubber polymer. Bit sqeeky, but excellent travel and load capabilities. Best trailer suspension ever used with supper low bed and compact.

http://www.dexteraxle.com/torflex_axles

Bet the Shocker is a whole lot more sophisticated. Wondering how the damping works?

[PaulM]

"It would appear" that there are some in here who are not quite so.....open minded.

I am one of these, and not ashamed to admit it. I have nothing against neat designs or new ideas as long as they work! I'm not saying this won't work and would be happy to be proven wrong, but I am quite skeptical. There is a reason every mass produced dirtbike on the market uses twin-legged telescopic front forks, they work!

In the dirtbike world, it's function before form!

[Sheriff Jon]

The suspension reminds me of the independent sprung rubber torsion type I had on the horse box I owned. Basically a square tube about 2 " with a second solid square bar somewhat smaller at 45 degrees inside. The resulting triangular spaces were filled with a rubber polymer. Bit sqeeky, but excellent travel and load capabilities. Best trailer suspension ever used with supper low bed and compact.

http://www.dexteraxle.com/torflex_axles

Bet the Shocker is a whole lot more sophisticated. Wondering how the damping works?

I haven't seen the Shockers particular design yet although the silver compression blocks look identical to what is used on the GTR, but your description is exactly how the set up is on my scooter. And odd as it may look, it just works.

[liveforphysics]

PWM shocker = 99 YZ125 perhaps? Definately an old Yamaha frame (the new ones are aluminum). I'm not going to spend the time to go through every year and model to find the exact version.



With this tail light/signal kit screwed on:



And from the glimpse of turn signal reflector showing by the headlight, likely the matching headlight/signal kit.



Add black spray paint + ebay plastics kit + electricity printed vinyl sheet = PWM shocker platform.

While this is a fine receipe for making a 1-off e-bike conversion, it's not something you can base a production model from.

Best Wishes,
-Luke

[maydaverave]

The trail ripper uses a similar suspension and it seems to work pretty good as seen here. http://www.youtube.com/watch?v=JW1HpzNlz9M It looks really cool to me but I guess we will just have to wait and see.

[Sheriff Jon]

PWM shocker = 99 YZ125 perhaps? Definately an old Yamaha frame (the new ones are aluminum). I'm not going to spend the time to go through every year and model to find the exact version.


With this tail light/signal kit screwed on:

And from the glimpse of turn signal reflector showing by the headlight, likely the matching headlight/signal kit.

Add black spray paint + ebay plastics kit + electricity printed vinyl sheet = PWM shocker platform.

While this is a fine receipe for making a 1-off e-bike conversion, it's not something you can base a production model from.

Best Wishes,
-Luke

I can understand being skeptical as this incorporates several new, or at least concepts new to this market, but there is a difference between being skeptical and being closed minded and in your case negative. Why all of the nagativity liveforphysics? Is it just in your nature to look for and point out fault in others, or this just a game to you to see if you can identify what parts YOU think may have been used and then insinuate the Shocker is little more than a cheap toy.

[liveforphysics]

Sheriff Jon- I see a photo of something to be a new production electric motorcycle for sale. To an inexperienced eye it may appear to be something unique and factory production built. However, I recognized the old motorcycle frame, the plastics, the stock ICE bike radiator, and the ebay non-DOT turn signal kit retro fit onto a 99 YZ125; and recognize the stock yamaha radiator. This is not speculation, this is a simple reality.

It's also a simple reality that you can't make a production motorcycle based on buying old steel frame yamaha dirtbikes and retro-fitting them. It's simply not cost effective or practical to do that.

Now, if someone wants to claim, hey, this is a neat E-conversion I made from an old yamaha dirtbike, I fitted my own unique suspension, an electric motor, battery and turn signals. They could then say someting like, "I did a really nice job making it look good, and I want to make a production product that is similar to how this turned out".

That seems like it would be a lot more straight forward way to present something. Maybe that makes me a no-fun stick-in-the-mud because I can easily see what is really shown in that photo. If you could see it's clearly an elaborate E-conversion done on a YZ125, would you mention it? would you pretend you didn't notice? What would you do?

-Luke

[Sheriff Jon]

Sheriff Jon- I see a photo of something to be a new production electric motorcycle for sale. To an inexperienced eye it may appear to be something unique and factory production built. However, I recognized the old motorcycle frame, the plastics, the stock ICE bike radiator, and the ebay non-DOT turn signal kit retro fit onto a 99 YZ125; and recognize the stock yamaha radiator. This is not speculation, this is a simple reality.

It's also a simple reality that you can't make a production motorcycle based on buying old steel frame yamaha dirtbikes and retro-fitting them. It's simply not cost effective or practical to do that.

Now, if someone wants to claim, hey, this is a neat E-conversion I made from an old yamaha dirtbike, I fitted my own unique suspension, an electric motor, battery and turn signals. They could then say someting like, "I did a really nice job making it look good, and I want to make a production product that is similar to how this turned out".

That seems like it would be a lot more straight forward way to present something. Maybe that makes me a no-fun stick-in-the-mud because I can easily see what is really shown in that photo. If you could see it's clearly an elaborate E-conversion done on a YZ125, would you mention it? would you pretend you didn't notice? What would you do?

-Luke

Of course you are free to make whatever assumptions and comments that you think that you see. GoPed is used to that kind of "know-it-all" and put it down attitude from many of their younger scooter customers. But from what I understand they actually do plan to bring this Shocker to market.

I believe the bike pictured is still a prototype, and may or may not have minor or major changes before it is offered for sale to the public. This is not something that I personally would be interested in, but I for one do not have the need to put a product down and critique against it based on one photograph and my own preconceptions.

I do not work 'for' GoPed, but yes I am friends with Steve Patmont (CEO) and a very happy GoPed owner user

[liveforphysics]

[quote="Sheriff Jon
Of course you are free to make whatever assumptions and comments that you think that you see. GoPed is used to that kind of "know-it-all" and put it down attitude from many of their younger scooter customers. But from what I understand they actually do plan to bring this Shocker to market.

[/quote]


These aren't assumptions of what I "think" I see. My eyes work fine, and it's a very professional and nice looking, but still obvious E-conversion of a Yamaha motorcycle. I made a quick diagram so you can see some of the things my eyes see in the picture.





Now, if he is planning to bring what is pictured to production, he is either going to need to buy about $2,000 in Yamaha parts to make each bike, or start combing ebay and craigslist to buy up old YZ125's.

I have no malice for this guy or his company, which I know absolutely nothing about. However, I can tell you with certianty that what is in the picture is a very nicely done E-conversion of an old Yamaha dirtbike and fitted with some VERY unique suspension.