Leaperkim Lynx 2700wh: 151V, 20" tire, suspension, 89lb

[UPONIT]

16 hours ago, Planemo said:

I don't want to insult your intelligence, but this video is quite a good overview of how to set things up. It's a very basic but has helped a lot of guys that are just getting into things. Theres plenty more in-depth tutorials out there if this one sends you to sleep

 

 

I'm never insulted by people sharing knowledge/help at any level. Thank you for the link. Curated technical info is much more efficient than random googling!

Never been interested in mountain bikes = I've never studied the evolution of bike suspensions. Now that the subject has become pretty central to EUCs, I'm interested.

9 hours ago, Duster said:

Both scenarios are just solved by stiffening the suspension, as long as the right weight springs were chosen for the rider in the first place.

Maintenance/performance issues aside, isn't that an area where air suspension is "better" than springs? Instead of having to configure EUCs with a variety of springs for different size users (inventory prediction nightmare?), an air suspension covers all of the weight spectrum?

---------------

One last confusing vocabulary issue: damping/dampener.

When someone says "compression dampening," doesn't that mean the same thing as "adjusting the spring to be more or less stiff" (stronger spring/higher psi)? In other words, there is no separate dampenER doing the dampenING during compression?

Whereas during rebound, there is a separate mechanism (a dampenER) that opposes the spring's expansive force or the air's expansion? Otherwise, the air/spring would be like an ejector seat.

Do I have that right? And does that apply to air and spring suspensions? That's the implementation on the V13's air suspension...

[Planemo]

19 minutes ago, UPONIT said:

I'm never insulted by people sharing knowledge/help at any level.

All good then! Heres another link which is quite good as well

 

19 minutes ago, UPONIT said:

One last confusing vocabulary issue: damping/dampener.

Same thing really, 'damping' is what the 'damper' does. The term 'dampening' is a bit grammatically incorrect tbh but it's one of those where everyone knows what you mean so it's not a problem.

19 minutes ago, UPONIT said:

When someone says "compression dampening," doesn't that mean the same thing as "adjusting the spring to be more or less stiff"

No. Damping is entirely separate from the spring action, whether that be coil or air. It's just as separate as your later comment re rebound damping.

But I think I know where you are coming from as in general, yes, rebound damping is more critical than compression damping. It's why many MTB'ers run little to no compression damping, partly also because of the stiction in the system which provides 'damping' in a way (a resistance to the coil spring/air piston). But we often need some rebound damping to prevent the 'pogo' effect. FWIW I have seen many, many EUC riders running way too little rebound damping and you can see it when they bounce up and down on the wheel like it's a trampoline. It should be far more controlled and this is where damping comes in. Too little damping leads to the tyre skipping between successive bumps and of course, any time the tyre loses contact with the terrain you don't have an ideal situation. The first vid gave a good example of too little rebound on the front - the forks extended at such a rate it pulled the front tyre off the road with it.

[UPONIT]

1 hour ago, Planemo said:

All good then! Heres another link which is quite good as well

 

Same thing really, 'damping' is what the 'damper' does. The term 'dampening' is a bit grammatically incorrect tbh but it's one of those where everyone knows what you mean so it's not a problem.

No. Damping is entirely separate from the spring action, whether that be coil or air. It's just as separate as your later comment re rebound damping.

But I think I know where you are coming from as in general, yes, rebound damping is more critical than compression damping. It's why many MTB'ers run little to no compression damping, partly also because of the stiction in the system which provides 'damping' in a way (a resistance to the coil spring/air piston). But we often need some rebound damping to prevent the 'pogo' effect. FWIW I have seen many, many EUC riders running way too little rebound damping and you can see it when they bounce up and down on the wheel like it's a trampoline. It should be far more controlled and this is where damping comes in. Too little damping leads to the tyre skipping between successive bumps and of course, any time the tyre loses contact with the terrain you don't have an ideal situation. The first vid gave a good example of too little rebound on the front - the forks extended at such a rate it pulled the front tyre off the road with it.

Thank you for the link and for the further explanation. I understand the concepts you explained. Makes sense.

But, take the V13 suspension, which I'm familiar with. The rebound damping is a separate mechanism and I understand its function. The compression shock is a single air chamber tube and piston. In that single tube, what is the separate mechanism damping the compression? Is it the stiction of the seals?

I thought the only compression adjustment one can make is changing the psi, making it resist being compressed more (or less). For instance, I run the shock at about 30 psi less than the recommend pressure for my riding weight. The shock compresses about 30% when I step on. The ride is WAY more cushy of course.  And since I don't do big jumps, I've never bottomed out (if that is even possible here).

So is the compression somehow being damped? How? Is it adjustable?

Thanks again for taking the time to help me with this. I want to be able to follow along and understand the nuances as people debate the pros and cons!

 

[Duster]

2 hours ago, UPONIT said:

Maintenance/performance issues aside, isn't that an area where air suspension is "better" than springs? Instead of having to configure EUCs with a variety of springs for different size users (inventory prediction nightmare?), an air suspension covers all of the weight spectrum?

Hmm. I'm not sure. I could've sworn both air and hydraulic suspensions have springs in their mechanisms. I do suppose that air has what hydraulics doesn't, which is compressibility. That would theoretically allow an air shock to provide the rebound without a spring... But again, I've only known Leaperkim hydraulic suspension, so I've never known air suspension to be able to forego springs.

Could someone with note expertise confirm it deny this?

[Rawnei]

3 hours ago, UPONIT said:

Maintenance/performance issues aside, isn't that an area where air suspension is "better" than springs? Instead of having to configure EUCs with a variety of springs for different size users (inventory prediction nightmare?), an air suspension covers all of the weight spectrum?

The advantage of air is that you can use a pump to adjust it instead of switching springs, once both air and coil is dialed in there's not a lot of reason to change it.

[Planemo]

53 minutes ago, UPONIT said:

But, take the V13 suspension, which I'm familiar with. The rebound damping is a separate mechanism and I understand its function. The compression shock is a single air chamber tube and piston. In that single tube, what is the separate mechanism damping the compression? Is it the stiction of the seals?

I'll be honest, I'm totally unfamiliar with the V13 setup, I've never looked at it. But it's entirely possible to combine a damping circuit in the same 'tube' as the coil/air spring. Maybe thats what they do. Does it have compression damping adjustment? And we prob need to put this in another thread

 

17 minutes ago, Duster said:

Hmm. I'm not sure. I could've sworn both air and hydraulic suspensions have springs in their mechanisms.

That wouldn't make any sense. The only spring I have ever seen in an air system is a small one for the purpose of negative, a bit like the negative air chamber in air shocks, to reduce stiction around sag point.

17 minutes ago, Duster said:

I do suppose that air has what hydraulics doesn't, which is compressibility. That would theoretically allow an air shock to provide the rebound without a spring...

I think you're getting a bit mixed up re air/hydraulic. Not helped by the recent argument over the terms in another thread on this very website. The result we have now is exactly what I knew would happen... 

[InfiniteWheelie]

I’m far from a suspension expert but the basics are actually simple once you learn it…

Firstly there’s the spring itself which is either a steel coil, or air which gets compressed. In both systems there is oil which must pass through a hole when the suspension compresses and rebounds. When this hole is adjusted to fully open, you have no damping so the spring alone is responsible for all the movement. You add damping by adjusting the hole to be smaller so the oil can’t pass through as fast as it want. This slows the rebound or compression.

All suspension is “hydraulic” because they all use oil for damping. Anyone who calls the Leaperkim suspension “hydraulic” is doing a disservice to people who don’t know better, and are causing confusion. We have linkage and fork type suspension, with either coil or air springs. So the Lynx has coil fork suspension.

Edited November 26, 2023 by InfiniteWheelie

[Duster]

33 minutes ago, InfiniteWheelie said:

I’m far from a suspension expert but the basics are actually simple once you learn it…

Firstly there’s the spring itself which is either a steel coil, or air which gets compressed. In both systems there is oil which must pass through a hole when the suspension compresses and rebounds. When this hole is adjusted to fully open, you have no damping so the spring alone is responsible for all the movement. You add damping by adjusting the hole to be smaller so the oil can’t pass through as fast as it want. This slows the rebound or compression.

All suspension is “hydraulic” because they all use oil for damping. Anyone who calls the Leaperkim suspension “hydraulic” is doing a disservice to people who don’t know better, and are causing confusion. We have linkage and fork type suspension, with either coil or air springs. So the Lynx has coil fork suspension.

That clears up a lot for me. Thanks!

My suspension knowledge comes from a decade ago, when I was 12 and experimenting with my Traxxas rc car's silicone shock fluid.

I had previously heard EYC reviewers referring to the veteran suspension as "hydraulic" specifically, which certainly informed my limited knowledge of our linkage v fork setups. I actually haven't read the other threads where this rhetoric is also occurring, so this is probably a common misconception.

[InfiniteWheelie]

@Duster No problem. Leaperkim themselves have been calling it “hydraulic suspension”, along with just about every uninformed YouTuber and a bunch of people here as well. Just because the majority are saying it, doesn’t mean it’s correct or makes sense. All suspension is “hydraulic”, not just forks. It’s ridiculous to refer to it by that name, especially when they only do so for forks.

Edited November 27, 2023 by InfiniteWheelie

[Planemo]

1 hour ago, Duster said:

My suspension knowledge comes from a decade ago, when I was 12 and experimenting with my Traxxas rc car's silicone shock fluid.

Don't beat yourself up, the Traxxas suspension is a perfect example of how it works in just about most applications despite it being a 'toy'. On the RC car it will be a coil spring over a hydraulic damper. The damping amount can be adjusted by either choosing piston heads with different sized bleed orifices or, as you did, by changing the weight of the oil. Between them both options give a huge range of damping adjustments. Ride height/firmness would be adjusted by swopping out the springs, just the same as Leaperkim. All thats changed on the EUC is size.

Don't underestimate what you can learn from playing with RC/Meccano/Lego/Scalextric etc etc as a child, or even as an adult...

Edit: The only difference with the RC car is that you wouldn't have separate bump/rebound adjustments because the piston head and/or oil would operate the same whichever way the piston was travelling. Higher end suspension generally uses shim stacks (thin plates of metal) which bend one way in one direction and lock in the other direction, separating bump (compression) from rebound. By changing the stiffness of the stacks on each you can alter the amount by which they deflect, therefore the amount of oil that passes through them. Some suspension uses a mix of orifice and shim stacks. All depends. But the mechanics behind it and how it works certainly isn't NASA material. Some lower spec suspension on say EUC/MTB uses adjustable orifices and this is what changes when you turn the knob on the leg.

Edited November 26, 2023 by Planemo

[UPONIT]

8 hours ago, Planemo said:

Does it have compression damping adjustment? And we prob need to put this in another thread

No, it doesn't. Changing psi is the only compression adjustment. There's a separate rebound damping unit, adjustable by hex-head valve.

Onwards to Lynx-specific suspension stuff...

I just watched Freshly Charged's (YouTube) review of the Lynx and they really loved it. They made special mention of how much they loved the suspension, and showed all kinds of bumping and jumping and hopping.

[Duster]

On 11/25/2023 at 10:22 PM, Planemo said:

Don't beat yourself up, the Traxxas suspension is a perfect example of how it works in just about most applications despite it being a 'toy'. On the RC car it will be a coil spring over a hydraulic damper. The damping amount can be adjusted by either choosing piston heads with different sized bleed orifices or, as you did, by changing the weight of the oil. Between them both options give a huge range of damping adjustments. Ride height/firmness would be adjusted by swopping out the springs, just the same as Leaperkim. All thats changed on the EUC is size.

Don't underestimate what you can learn from playing with RC/Meccano/Lego/Scalextric etc etc as a child, or even as an adult...

Edit: The only difference with the RC car is that you wouldn't have separate bump/rebound adjustments because the piston head and/or oil would operate the same whichever way the piston was travelling. Higher end suspension generally uses shim stacks (thin plates of metal) which bend one way in one direction and lock in the other direction, separating bump (compression) from rebound. By changing the stiffness of the stacks on each you can alter the amount by which they deflect, therefore the amount of oil that passes through them. Some suspension uses a mix of orifice and shim stacks. All depends. But the mechanics behind it and how it works certainly isn't NASA material. Some lower spec suspension on say EUC/MTB uses adjustable orifices and this is what changes when you turn the knob on the leg.

Thanks to you too!

Yeah, the Traxxas suspension resembles the leaperkim suspension, but I never had the allowance to buy the expensive air shocks back in the day... As far as I knew, air shocks were like the stock oil shocks, just replacing the silicone for air (somehow managing to make the air pressure approximate oil weight).

Now, with this thread's context, I vaguely understand that the air replaces springs, and all suspension uses oil, and the differences between linkages (Begode King Song, and v14) VS fork (V13, Shermans, and EB) are where the "hydraulics" term was misattributed as a differentiating feature.

Kinda itching to get back into the RC cars now...

[stizl]

 

[techyiam]

Here's EEVEE's Veteran Lynx Review. Consensus seems to be Leaper Lim has knock it out of the park.

 

Edited November 29, 2023 by techyiam

[Rawnei]

Unfortunately Denis also don't understand that 250 cycle degradation numbers for the 50S cells come from a torture test at max discharge and charge, this community often acts like a big echo chamber without any fact checking, even more unfortunate when reviewers can't even fact check things.

 

[Rawnei]

@Jason McNeil what do you think of the rear light on the Lynx? Would it be possible to ask LK to change the firmware so that it doesn't blink all the time? Just steady red with brighter break light would be awesome.

Turn signals overall seems completely useless on an EUC both for the fact that it happens after rider already turned but also that many EUC riders like to carve so it's not really signalling anything useful.

 

mod edit: Split turn signal discussions to a new thread here: https://forum.electricunicycle.org/topic/34769-about-turn-signals-built-in-to-eucs-split-from-leaperkim-lynx/

Edited December 1, 2023 by RagingGrandpa
(added URL)

[Drunkard]

12 hours ago, Rawnei said:

this community often acts like a big echo chamber without any fact checking

was there data released on degradation using lower discharge rates? 

[Rawnei]

10 minutes ago, Drunkard said:

was there data released on degradation using lower discharge rates? 

Personally I haven't seen any good data for that but I haven't searched that much either.

There are discussions about it going on in this thread:

 

Edited November 29, 2023 by Rawnei

[cegli]

1 hour ago, Drunkard said:

was there data released on degradation using lower discharge rates? 

They age a little better than the 50E, but it's almost negligible:

Considering they support much faster charging than the 50E, I'm betting they'll hold up to aggressive braking and fast charging better than the 50E as well.  2.5A (50E) vs 6A (50S).  That means the batteries are within manufacturer spec charging at ~1300W for the 50E and ~3100W for the 50S, given the 36s4p Lynx configuration.

I'm not sure how much wattage heavy braking down a hill generates, but I bet it's above 1300W.

Edit - I just did some quick math on how much wattage emergency braking pushes into batteries:

Scenario: 82kg person + 40kg wheel going 72km/hr (20m/s).  Emergency brake to a stop in 2.5 seconds.  This seems reasonable based on eevees braking tests from 50km/hr, which appeared to take about 2 seconds from their video.

EK = 0.5*122kg*20m/s^2 = 24400J
P = W/T = 24400J/2.5s = 9760W

Now this is an extreme situation (and it only would happen for 2.5 seconds), but I see the benefit of a battery pack specified to take 3100W continuous vs 1300W continuous.  Down a steep hill, large amounts of power could be dumped into the batteries for longer periods of time...

Edited November 29, 2023 by cegli

[Rawnei]

31 minutes ago, cegli said:

I'm not sure how much wattage heavy braking down a hill generates, but I bet it's above 1300W.

Edit - I just did some quick math on how much wattage emergency braking pushes into batteries:

Scenario: 82kg person + 40kg wheel going 72km/hr (20m/s).  Emergency brake to a stop in 2.5 seconds.  This seems reasonable based on eevees braking tests from 50km/hr, which appeared to take about 2 seconds from their video.

EK = 0.5*122kg*20m/s^2 = 24400J
P = W/T = 24400J/2.5s = 9760W

Now this is an extreme situation (and it only would happen for 2.5 seconds), but I see the benefit of a battery pack specified to take 3100W continuous vs 1300W continuous.  Down a steep hill, large amounts of power could be dumped into the batteries for longer periods of time...

More importantly it's interesting to understand what can happen to a high capacity cell during this type of strong braking, one theory regarding MG50T fires was that regen braking could be part of the problem and also a big reason to choose high performance cells.

[stizl]

Effortless 45 degree climb! WW’s title says “nothing comes even close”. That answers my question about low-speed torque vs the Patton, although other reviews still gave the starting torque edge to the Patton from a dead stop. 
 

 

Edited November 29, 2023 by stizl

[Rawnei]

2 hours ago, stizl said:

Effortless 45 degree climb! WW’s title says “nothing comes even close”. That answers my question about low-speed torque vs the Patton, although other reviews still gave the starting torque edge to the Patton from a dead stop.

I'm curious how they come to that conclusion, how do you even test that?

[Ronin]

3 hours ago, stizl said:

Effortless 45 degree climb! WW’s title says “nothing comes even close”. That answers my question about low-speed torque vs the Patton, although other reviews still gave the starting torque edge to the Patton from a dead stop. 
 

 

This shows that the motor of the Lynx is extremely powerful. On flat ground, i observed the torque kicking out from 10-15mph, after gaining momentum. This is because the pedals are quite high with less immediate leverage to push the wheel (its still ok). High pedals are ideal for trail riders. With a lower pedals mod I think the low end torque of the Lynx will be on par with the Patton (few people are working on such mod). 

Edited November 29, 2023 by Ronin Ryder

[stizl]

1 hour ago, Rawnei said:

I'm curious how they come to that conclusion, how do you even test that?

It could definitely be tested with a dyno and measurements of distance and force applied to the pedals and/or pads, which could also show what @Ronin Rydermentions above.

The feedback from the reviewers, however, appears to based on feel. The Patton, in stock form, has the most (or the sensation of the most) accessible starting torque. It also makes sense with the smaller wheel diameter. 

[UPONIT]

1 hour ago, Ronin Ryder said:

This is because the pedals are quite high with less immediate leverage to push the wheel (its still ok). High pedals are ideal for trail riders. With a lower pedals mod I think the low end torque of the Lynx will be on par with the Patton (few people are working on such mod). 

Lower pedals sure as hell helps the V13's low-end torquelessness. I'm sure that mod will make the Lynx noticeably beastier than it already is.