Sherman-S 3600wh: 100V, 20", suspension, 97lb

[techyiam]

Hsiang hosted a Sherman-S demo ride in NYC. Here's one of the riders first impression. It sounded quite positive. Time-stamped. 

 

 

[Tawpie]

3 minutes ago, techyiam said:

It is hydraulic, because they are using an oil damper. But they separated the function for each leg. One struct is dedicated as a damper, and the other as a spring. For the struct that contains spring, it should be filled with oil, but it doesn't have to.

Got it. It's literally taking a coil over and putting the coil in one leg and the shock/damper in the other.

[Jon Wall]

Both legs are dampers and sprung. Just split rebound and compression. Nothing special. Both legs have oil for valving 

and lubrication 

[Tawpie]

I now understand why some are concerned about twisting and whether or not the two legs are sufficiently supported to prevent issues. The two legs are doing two different jobs so calculating the dynamic loads and stresses is "quite complicated".

nvm... I was just curious if there was oil in that leg, evidently there is!

Edited December 6, 2022 by Tawpie

[MrMonoWheel]

1 hour ago, Road Runner said:

Adam's broken gasket

 

 

 

 

1 hour ago, techyiam said:

The way the dust seal on the suspension struct got damaged looks odd.

Perhaps it was damage during disassembly?

Honestly it looks like the seal shit the bed due to all the lateral forces being applied while riding. If the force on the shocks were more vertical like in an MTB or motorcycle with proper rake angle, it wouldnt wear as hard (maybe), but with the EUC its constantly having force applied from the front and back depending on if you are accelerating, braking, hitting stairs, jumps, etc. Over hundreds of miles I could see it slowly killing the suspension (if its not engineered correctly).

6 minutes ago, techyiam said:

It is hydraulic, because they are using an oil damper. But they separated the function for each leg. One struct is dedicated as a damper, and the other as a spring. For the struct that contains spring, it should be filled with oil, but it doesn't have to.

I may be wrong, but when rebuilding the forks of my motorcycles the spring and damper system were all integrated into one unit, all of which was submerged in oil. The damper system sits inside the spring.

[Jon Wall]

I don't understand how this nonsense gets started. 2 springs, 2 valve stacks. 1 spring in each leg. One valve is rebound and a spring to hold it at length. The other side, again a spring and the opposite function valve stack. Simple simple . Both legs are a wet system.  Both legs sprung

 

 

 

[Slartibartfast]

12 minutes ago, techyiam said:

Theoretically, since it doesn't function as a damper, it could be dry lubed or greased.

Interesting. Why do you say it doesn't function as a damper? I thought it did and that that is what the dials on the top were for.

Specifically I thought one side limited how quickly oil was able to flow in one direction and the other side controlled how quickly it could travel in the other, and that both sides allowed oil to "return" without restriction.

[Jon Wall]

No. Both springs work in compression. 2 spring preload adjusters up top. 1 on each leg. The valving is just separate left and right. Springs are all normal stuff. Not like a light weight mtb short travel fork at all. More like most motorcycle forks use a spring in each leg

 

[Tawpie]

2 minutes ago, Jon Wall said:

No. Both springs work in compression. 2 spring preload adjusters up top. 1 on each leg. The valving is just separate left and right. Springs are all normal stuff. Not like a light weight mtb short travel fork at all. More like most motorcycle forks use a spring in each leg

 

apologies, I hid my post asking if one spring was being compressed and the other stretched, because sitting here reading it I got all confused again and my post sounded foolish.

Edited December 6, 2022 by Tawpie

[Slartibartfast]

8 minutes ago, Tawpie said:

I get it now I think... one leg is smashing the spring when the wheel is moving upwards, that's the compression side. The other leg is stretching a spring when the wheel is moving upwards, that's the rebound?

That's not my understanding. From what I understand both sides have springs which compress as the wheel moves upwards and this provides the "suspension" as most people think of it.

Additionally to this both shocks are also filled with oil and the restriction of this oil provides the "dampening". The idea of the dampening is to reduce the speed at which the spring compresses (and decompresses). This is primarily to prevent the springs "bouncing" back to there original height after a bump as this "bouncing" will lead to an oscillation. Without dampening the rider would bob up and down for a bit after hitting a bump.

There is of course more to it but that's the general idea.

Edited December 6, 2022 by Slartibartfast

[Jon Wall]

Only the split rebound on the left leg , and compression 

on the right leg is unique .  The spring orientation is all common 

 

[Paul A]

1 hour ago, Unicycle Santa said:

If the force on the shocks were more vertical like in an MTB or motorcycle with proper rake angle, it wouldnt wear as hard (maybe),

 

Rake angle non existent.

Does seem like this is a contributing cause of failure.

Previous other makes and models have similar orientation though.

Maybe over time, they will prematurely fail too and reports will begin.

 

The S22 suspension might be the better design for durability?

Edited December 6, 2022 by Paul A

[MrMonoWheel]

Im not sure what all the hubub is about regarding how the damping works, so I will clear it up. Both shocks have a coil spring to provide the suspension action. One leg has valving that limits the speed of compression, the other has valving to limit the speed of rebound. Both legs are sprung and both (should be) full of oil. Also, different weight shock oil can always be used to tune the compression/rebound to the person's liking.

[Slartibartfast]

32 minutes ago, Unicycle Santa said:

Also, different weight shock oil can always be used to tune the compression/rebound to the person's liking.

Each of the forks have adjustment knobs at the top so you shouldn't need to change the oil to tune your setup, unless you're after something out of the adjustment range.

[techyiam]

I stand corrected. There should be a coil spring and oil damping in each leg. But reviewers can confirm. Just check the preload. Unless someone can point to a picture or video showing a coil spring in each leg.

I can't find the source of where I read or watched about the separate function of the suspension structs. But now that it has been pointed out about the compression damping adjustment on one leg, and the rebound damping on the other leg, we can be certain that there is oil damping in both legs.

And after going back and scan through EEVEES Sherman-S disassembly video, I see a preload adjuster is on each leg. And hence, there is a very high probability that there is a coil spring in each leg.

Thank you pointing that out.

This is great news for me. LeaperKim did not cut corner on the structs, and so the lateral stresses will be greatly reduced. With the higher headroom recently added, the Sherman-S is looking better than ever.

For a quality high speed commuter, the Sherman-S and the V13 are both looking really good to me.

Edited December 6, 2022 by techyiam

[Paul A]

Did Adam say why the gasket broke?

[MrMonoWheel]

1 hour ago, Slartibartfast said:

Each of the forks have adjustment knobs at the top so you shouldn't need to change the oil to tune your setup, unless you're after something out of the adjustment range.

Well yeah thats what I am saying. If you were to want a feel outside of the range you could put in thicker or thinner fluid. Pretty common on motorcycles where the factories often dont put a heavy enough oil in.

[BKW]

 

[Planemo]

49 minutes ago, techyiam said:

And hence, there is a very high probability that there is a coil spring in each leg.

I thought we covered that there was ages ago in this thread.

Re the seal, the fact it has pulled away from the leg and has damage pretty much bang in line with the damage on the lower section I can't help but feel the seal got ripped out at the same time by whatever damaged/scraped the lower section. Just a possibility.

If not, it's possible that air pressure build up in the leg on compression simply blew out the seal, not unheard of on MTB's. Can either be down to too much lube being applied to the seal on fitment or them simply not having a tight enough interference fit in the leg.

[techyiam]

9 minutes ago, Planemo said:

I thought we covered that there was ages ago in this thread.

That's great. 

Can you kindly provide the link that shows a coil spring in each leg.

[Planemo]

7 minutes ago, techyiam said:

That's great. 

Can you kindly provide the link that shows a coil spring in each leg.

Not sure I can, but the fact that there is a preload adjuster on top of each leg would be a bit odd if there wasn't a spring underneath it.

[techyiam]

5 minutes ago, Planemo said:

Not sure I can, but the fact that there is a preload adjuster on top of each leg would be a bit odd if there wasn't a spring underneath it.

I agree. But you never know.

In any case, I hope that somebody will do preload soon in a video.

[Planemo]

34 minutes ago, techyiam said:

I agree. But you never know.

I know that Chinese products can be a bit random in their design but fitting a 'decorative preload adjuster' would be a new one on me!

[Planemo]

2 hours ago, Unicycle Santa said:

Im not sure what all the hubub is about regarding how the damping works, so I will clear it up. Both shocks have a coil spring to provide the suspension action. One leg has valving that limits the speed of compression, the other has valving to limit the speed of rebound. Both legs are sprung and both (should be) full of oil. Also, different weight shock oil can always be used to tune the compression/rebound to the person's liking.

Agree with all of that except I don't believe the legs are 'full' of oil. I suspect that the damping circuits have their own (smaller diameter) tube ie 'twin tube' design and this would appear to be the case given the diameter of the piston head shown in the previous pic. This would mean the stanchion wiper seals don't share the same lubricant. They may well just rely on grease in addition to an oil-soaked sponge fitted internally to the outer leg just above the wiper seals to provide a little extra help in lubing the wiper seals, as per usual MTB standards. An internal pic of the black outer tube would confirm the presence of an oil sponge or not. Would also be interesting to see how many PTFE bushings there is and what depth the bushings are. This would give us an idea of how much surface area there is to support everything and the forces being applied to them. I believe they would need to be pretty large (or numerous) given the lack of rake and therefore side load in this application. But with more bushing area comes more stiction so....it's a juggling game.

[techyiam]

43 minutes ago, Planemo said:

but fitting a 'decorative preload adjuster' would be a new one on me!

I was thinking more along the line of saving money by not having another part to deal with in inventory, or needing to not get mixed up during installation, or having the other cap designed and tooling made.