Sur-Ron - New Mid drive Bike

[motomoto]

I got some good riding in today at Prairie city OHV. I did the bigger kids track and the beginner motocross track. I thought I was
hauling the mail but on the motocross track a kid on a 125 2-stroke was putting 2 seconds a lap on me. 30 hp vs. 4 hp.

When I went back to the kids track the second time something shut the bike down to half power after about 5 laps so I called it
a day. The motor did not feel hot at all, just warm. It was a solid 20 minutes before it shut down the power.
I used about 25% of the pack. It reset itself and is back to full power.

[Merlin]

2 seconds only on a mx track?
that sounds nice.
please make videos from the 30-40-50 foot doubles you are entering with this 4kw beast

[Aebrennan]

I wonder if the English to EUR translation doesn’t work well on Endless Sphere, or is the arrogance setting set to maximum on the non English speaking parts of the world?

[Merlin]

... Should I fill Google translate with your post now?
Because I don't understand what your point is?

[Aebrennan]

Maybe it’s my calculator but if I convert minutes to seconds I multiply by 60?

20 solid minutes x 60 seconds = 1200 seconds but your answer is 2?

[Aebrennan]

Maybe it’s my English fail!
I see you are referring to the lap time difference?

[Merlin]

Dude.. Take a look on your left arm... Is there still a needle plugged?

Wtf are you talking about?

He wrote he was riding on a mx track and a 125ccm kid was 2 seconds faster.

So why and what do you calculate in minutes?

[Aebrennan]

I apologise
I will not post again without reading comments properly
I thought you were referring to the run time prior to shutdown
I am impatiently awaiting the arrival of these bikes and in defence mode

[concrete]

Have people seen this video of a Sur-Ron Bee yet? https://www.youtube.com/watch?v=nPHLXLIL7Zs

[motomoto]

2 seconds only on a mx track?
that sounds nice.
please make videos from the 30-40-50 foot doubles you are entering with this 4kw beast

It was a beginner track. I did hit an uphill jump at the end of a straightaway (about 30 mph) and it took the hit fine. The frame
seems solid.

[motomoto]

2 seconds only on a mx track?
that sounds nice.
please make videos from the 30-40-50 foot doubles you are entering with this 4kw beast

It was a beginner track. I did hit an uphill jump at the end of a straightaway (about 30 mph) and it took the hit fine. The frame
seems solid. I played with the Mavic Pro today in beginner mode and plan to take it to the track this week and put it in the middle
of the track on active track spotlight. I think the camera will follow me around the track.

[Aebrennan]

A very detailed story here about the company and the bikes, although not sure how accurate it all is.
I found a few differences in what i have been told from the company, but a good read and a lot of detailed pics.

https://evnerds.com/electric-vehicles/e ... e-sur-ron/

[macribs]

Can someone explain how the linkage of the rear suspension will work and how linkage will affect and improve performance of rear suspension, and what theoretical benefits this rear suspension has over say a simple solution like the enduro frames?

I can picture how a double whishbone works, but never paid close details to rear end of vehicle as for most cars there is where things get really complicated with various usage of linkage etc.

[Rube]

Hi Macribs, that's an interesting question with a couple of answers. An easy explanation is seen in the evolution of motorcycles from unified rear triangle (URT), think twin shock on the swing-arm, to single shock linkage on modern sports bikes.

Tuning the linkage offers potential to optomise suspension geometry and squat/ anti squat characteristics throughout the range. Combined with progressive rate springs, adjustable compression and rebound dampening the rising rate, linear or falling rate linkage ratios control shock movement to maxamise drive traction, bump and braking control.

The problem with URT, such as the enduro, is geometry (e.g. wheelbase), squat/ anti squat, compression and rebound, and braking characteristics will change (often dramatically) throughout the travel. Also URT is a poor design for isolating drive torque from loading the shock, generally the current crop of frames fail in this regard. That's many seek Horst link designs like the Norco.

We need to champion better suspension designs. Unfortunately, the new Luna Apex frames also have a URT.

For manufacturing, linkages allow one frame to be used for both long and short travel suspensions, such as motard and dirt, while reducing the compromise of drive torque acting on suspension.

Btw - I'm no expert many on the forum are more knowledge. For example, Snowychild's frame addresses rear suspension rate, and separation of motor torque acting on the shock by tying motor torque to the swingarm. The motoped does this pretty well but a shock linkage would improve the design.

Cheers

[macribs]

So as the swing arm compresses the linkage works the rocker arm. The rocker arm compresses the shock while also working the opposite side of rocker arm to move the "wishbone". The "wishbone" got a pivot point on the frame too.

So here is where the linkage outsmarted me. What is the job of the wishbone? How does the movement of the wishbone influence the shock movement or the forces working on the swing arm? Looking at the pics below we can see the shock got a straight line from the frame mount to the swing arms "hi point".

I can briefly remember to seen a build or build sketch that used a similar swing arm. Will a swing arm alone shaped like that have any positive effect on shock and damping forces? Or does that curved swing arm not make any difference without the linkage too?

[Rube]

Linkage actuation depends on suspension travel, the design is primarily influenced by adaptability to meet min and max travel as per design criteria for one frame for steet and off road. Don't think of the 'whishbone'/ linkage as optimal for anything, instead it's to lower production cost first and second to lower design compromise. Much less achievable with URT. If you changed the central dog bone the ratio changes without additional components.

[madin88]

The Linkage offers progressive damping and/or spring rate.
Otherwise it is usual single pivot or URT with the motor attached to the frame body.

[FlightService]

McRib:

Are you referring to the A-arm the shock pass through the hole of or the swing arm mounting bracket that the rocker arm is attached to?

Edit: Also, this suspension arrangement does not look like the rear linkage set-up in the dirt-bike photo in the other thread.

[sn0wchyld]

So as the swing arm compresses the linkage works the rocker arm. The rocker arm compresses the shock while also working the opposite side of rocker arm to move the "wishbone". The "wishbone" got a pivot point on the frame too.

So here is where the linkage outsmarted me. What is the job of the wishbone? How does the movement of the wishbone influence the shock movement or the forces working on the swing arm? Looking at the pics below we can see the shock got a straight line from the frame mount to the swing arms "hi point".

I can briefly remember to seen a build or build sketch that used a similar swing arm. Will a swing arm alone shaped like that have any positive effect on shock and damping forces? Or does that curved swing arm not make any difference without the linkage too?

The linkage setup here makes it so the ratio between the movement of the rear axle and the movement of the shocks 'rear' axle (the 'shock attachment' point in FlightService's image above) changes throughout its range of suspension compression. In this case, the ratio decrees - thereby increasing the force required to compress the suspension further. That way it feels 'soft' for the first say, 1/3rd of the compression, stiff for the middle 1/3rd, and very hard for the last 1/3rd, making it very difficult to bottom out. The same thing would happen if it was simply attached to the swingarm as in the 2nd pic (no linkages) but the difference in how 'stiff' it gets would be much less. A linkage like the 1st pic can have a change in ratio from 1:4.5 that decreases to 1:2, where the 2nd pic will change from perhaps 1:3.4 to 1:3.0. Note these are not the actual numbers, just guesstimates for comparison.

Another way of thinking about it is a fulcrum/leaver setup:

the 1st bike with its linkages effectively means that the fulcrum moves to the right as you compress the suspension - so your 'effort arm' gets smaller, and the effort required to compress the suspension increases. For the 2nd bike pic, the fulcrum doesnt move, so the effort required remains approximately the same, no matter how much the suspension is compressed (in truth the fulcrum does move in both cases, but far less for the 2nd bike). The wishbone/dogbone setup simply allows the designer ( ie sur ron) to tune where the fulcrum is positioned at any given point in the suspensions compression. In particular, it allows for a 'progressive' rate of compression, so the effort required to compress the suspension increases exponentially, giving good compliance through most of the range of travel, while still preventing bottoming out.

hope that helps... haven't had my morning coffee so that might actually be gibberish.

[macribs]

Thanks guys for taking the time, now it kind of makes more sense. At least I understand how and why. But to implement something like that on my own.....is there any open source design for these kind of things? Progressive damping is something that is very much spot on to what I had in mind. Main goal not to bottom out, yet to have decent comfort for smaller bumps and slow speed cruising without having to resort to costly MX shocks that anyway would be a tight fit due to the eye to eye length.

I seem to recall an entire thread about goodies like suspension inner workings suddenly vanished a while back.....sad we lost all that.

[sn0wchyld]

Thanks guys for taking the time, now it kind of makes more sense. At least I understand how and why. But to implement something like that on my own.....is there any open source design for these kind of things? Progressive damping is something that is very much spot on to what I had in mind. Main goal not to bottom out, yet to have decent comfort for smaller bumps and slow speed cruising without having to resort to costly MX shocks that anyway would be a tight fit due to the eye to eye length.

I seem to recall an entire thread about goodies like suspension inner workings suddenly vanished a while back.....sad we lost all that.

http://www.bikechecker.com/
about the only one i know of. in my case (for my custom frame, see sig) i used fusion 360 and did the rest of the maths myself as i couldn't get the linkage software to work.

[FlightService]

4 bar linkage is what this is called in the engineering world.

There are a few visualizers out there.

Making little models out of cardboard popsicles sticks erectorsets always helps visualize your final design intent.

[madin88]

4 bar linkage is what this is called in the engineering world.

No, a 4-bar linkage is something differnet.
The surron has a SINGLE PIVOT swingarm with linkage to the damper for PROGRESSIVE damping. sn0wchyld has explained it pretty good.

[FlightService]

4 bar linkage is what this is called in the engineering world.

No, a 4-bar linkage is something differnet.
The surron has a SINGLE PIVOT swingarm with linkage to the damper for PROGRESSIVE damping. sn0wchyld has explained it pretty good.

Nah. The upper A-arm, my degree from a top 30 Engineering School in Mechanical Engineering, 10 years of Engineering experience and http://ffden-2.phys.uaf.edu/211_fall201 ... urBar.html all disagree with you.

It's still a 4 bar linkage


Edit: I see where madin88's confusion is coming in and from some quick research it is a common misconception/miscommunication. A single pivot would be solely based on the swing arm attachment and shock position. This is a 4-bar because the shock, upper A arm and rocker link are all connected. You CAN oversimplify and say the rear swing arm is a single pivot, but that wouldn't be an accurate description of the rear suspension. Just a description of the swing arm.

[FlightService]

Since there seems to be confusion as to what a 4-bar linkage is and how it works. Here are some links to play with.

http://dynref.engr.illinois.edu/aml.html

http://www.mekanizmalar.com/fourbar.html

https://www.desmos.com/calculator/iuprdl6sxk

Have fun!