Inside Ride Kickr E-Flex Trainer Motion System

I will leave the word “natural” out for now.

To answer the main question, yes, the leaning action is directly linked to steering the handle bars. It won’t lean without input from and/or loose control allowing steering to happen.

You can lean from steering directly or leaning it via the saddle and pedals.

How does this compare for comfort with other solutions rocker plates / rollers?

I’d say it’s on par. I’m planning on a fuller review and have some notes already.

But it allows rocking in a similar way to my other rocker models, and the motion rollers I built. The motion control is different than any other I’ve ridden, but I got comfortable with it after just 4 hours on it (along with my mods after the first 2 hours).

None of these are going to feel natural 100% of the time. The reason being that the roll center (the pivot point) moves depending on what you’re doing.

For casual riding outside, the pivot point for the side to side motion is probably right around where the tire meets the road. Your tires do not weave left right.
For sprinting / climbing (high torque) - it moves to around your crank spindle and your tires weaves side to side.

I don’t think you can design an active pivot based on how hard you’re working. Most rocker plates have this pivot 1-2" below the natural point exaggerating the sway. This thing has it at 0, so it will feel better. I’ve only seen a few that move the pivot to a sprint/climbing point - and one suspended DIY on the Facebook group.

I haven’t played with it, but I’m guessing having the pivot about 1" above the ‘surface’ would be the best all around. It’s tricky to build a DIY setup for that. I tried the Saris one, and was surprised how much the forward/aft movement came into place even at 125w. At any rate, the closer the pivot point is to the rear axle, the better it will feel sprinting hard.

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  • It’s not easily possible if by “how hard you’re working” you mean physical pedaling effort. That would require a some level of connection between input power and rocking pivot location.

  • However, having a movable pivot that varies from lean angle is theoretically possible. Various cam and linkage designs could achieve altered input to output for lean angle. I have penned several myself and built one so far. I’ve tested another that helped me evaluate direction for some future testing I plan to do.

  • That is true for the rear of the E-Flex. But the front is more complex than that. Ignoring fore-aft movement, the lean control on the E-flex locks the front position at the axle, and allows rotation around that axle. Couple that with the lean angle and you get an interesting “virtual location” of the front wheel contact through travel. I haven’t tried to map it (but want to in SolidWorks) to see where it really goes in lean travel.
  • This is often overlooked by many. They jump to the “it must pivot on the tire contact patch” location. that is likely true for some cases, but certainly not true in all cases. The reality is that it varies with rider input via handle bar lean and steering angle. It’s more complex than people consider and part of what makes this tricky to nail.
  • Correct observations overall. I wish I had the tools to capture what I want to see from actual riding, to more accurately consider the real pivots in the range of uses.
  • I’ve built one crazy model with special motion and axis location. It was a flop initially, but upon recent consideration, I need to re-evaluate it with some mods.

TL;DR… Crazy long post as my review to follow (who’s surprised I got a little wordy :stuck_out_tongue: ).

  • Short answer is that I like it in the stock form, but it’s much more to my liking after reducing the leveling and centering forces.
  • Overall, I am very happy with the E-Flex. It gives a basic feel close to my other rockers, with some differences in force input and directions.
  • I plan to do some more testing to see if I can get it even closer to what I see as the best solution possible.

E-Flex Initial Impressions:

  • The shipping package was small and light when delivered. It almost seems like the E-Flex couldn’t all be in there, but it is.
  • The two bases are well protected in the packaging. Once removed from the box, the two bases are light and small. This leads to the E-Flex being easy to move around for setup.
  • The E-Flex looks very clean with a professional build quality. It has the look and feel of a premium product, and is worth the price from that perspective.
  • One small issue, when testing the Fore-Aft motion by hand, I heard some squeaks. Turned out that two of the o-rings were rubbing against the sides of the slots at the mounting points to the outer tubes.
    • The tubes are deburred well, and won’t likely lead to wear on the o-rings, but the noise was something I wanted to eliminate. I added a small piece of Gorilla tape to the sides of all slots, and that silenced the Fore-Aft motion.


  • They are lacking detail in certain areas.
    • Use of the different leaf spring setting is not clear and lacks specific instruction about removing screws, and then swapping the part orientation.
  • The order of operations could be improved for more linear flow.
    • The leaf spring info comes after installing the Kickr on the rear section. It should be first, before any install steps.
  • There is no mention of the steering/lean lock knob on the front section. This should be covered and explained.
    • Despite the oversight on the steering lock, there is coverage of the rear tilt lock, that is used for shipping. This is most likely because it needs to be “unlocked” for final use.
  • Per the instructions, you position the middle leg of the Kickr a measured distance from the front clamp. This works alright, but I wonder if there is an easier way that doesn’t require the person to measure.
    • Perhaps the rear of the Kickr could be positioned flush with the leaf spring as a landmark, and still hit the same position without the need to measure?
  • The instructions show the front support and clamp positioned ahead of the fork.
    • I notice that Ray Maker installed his 180* from that, with the steering lock at the rear of the fork. This makes sense to me and puts the lock within reach while on the bike (at least for me and my bike size and arm reach).
    • I wonder if this “backwards” installation should be the default position shown by Inside Ride?


  • Aside from the instruction notes above, The installation and setup are relatively easy.
  • I love the finished look. It takes up a very small footprint compared to even my smallest rocker plates.
  • I also love the low stack height. The E-Flex sets the bike at roughly the same height as it is with regular wheels. This makes mounting and dismounting very easy. It doesn’t require stepping onto a platform like most rocker plates (that often raise the bike 3-5” higher).

First Ride, and Use Discussion:

  • Rocking Movement (Left-Right Pivot):

    • Typical rockers pivot on the “Roll Axis” that is around the effective contact point of the front and rear tire to the ground. There is no “actuation” connection between the bike other than a left-right weight shift controlled by the rider via input to the handlebar, saddle and/or pedals. This requires input from the rider to initiate and control the rocking motion:
      • At the handlebars, this is nearly vertical direction of motion for control (pull up / push down on opposite sides of the bars).
      • At the saddle, this is nearly horizontal direction of motion for control (shift the saddle left or right with your hips, waist and bottom).
    • The E-Flex rider input on the handlebars is very different when compared to all the other rockers I have used. The fork mount allows rotation around the vertical axis where the front hub would go.
      • That makes the handlebar motion rotate mostly horizontal with respect to the ground. Essentially, it is 90* off a typical rocker design described above.
      • Importantly, with the E-Flex design, the lean angle and steering of the handlebar are directly linked. This is because the rotation axis and plane at the “hub” are connected to the fork and handlebar. This connection, combined with the head tube angle and fork offset of the bike, lead to a sync of motion between handlebar turn angle and bike lean angle. One can’t happen without the other, and they always happen at the same rate.
      • As such, the initiation and control of the rocking on the E-Flex is different from all other rockers. You can lean the bike by either method (or combination) as discussed below:
    • Lean at Saddle: While seated on the E-Flex, I make a subtle left-right shift driven from my bottom on the saddle. The timing is as follows:
      • I push the bike to the left at the saddle, when the right foot goes down to the bottom of the stroke.
      • I push the bike to the right at the saddle, when the left foot goes down to the bottom of the stroke.
      • This is a subtle and natural motion that I do now, after many years on rockers. The main difference here, is that when I am leaning the bike mainly from the lateral saddle movement, the handlebars are also steering since they are connected.
      • This matters because you need to keep a relatively loose hold of the bars to allow the bike to rock left and right. If you hold the bars stiffly, you will prevent or stifle the rocking motion. This can be good or bad, depending on what you want at any given moment.
      • Compared to what I feel outside and on my rockers, the steering action is a bit odd, for seated efforts. It’s not at all what we experience with minimal rocking outside (around 2-3*) because that comes with minimal steering action and is almost purely left-right from the saddle and up-down on the handlebars.
      • Seated riding is good in the addition of the rocking for comfort, but the feel at the bars is just not quite right to me when compared to regular rockers.
    • Steer at Handlebar: While standing on the E-Flex, I rock the bike gradually left and right, in a timing similar to what I do outside. It’s the basic push/pull sequence that we do while outside, with some notable differences I will discuss later.
      • I pull the right side of the handlebar back, when the right foot goes down to the bottom of the stroke. Simultaneously, I push the left side of the handlebar forward.
      • I pull the left side of the handlebar back, when the left foot goes down to the bottom of the stroke. Simultaneously, I push the right side of the handlebar forward.
      • This all makes sense on one level. When riding standing outside, we adopt a rhythmic left-right rocking motion of the bike. That rocking is what we all see and focus on because it is most easy to identify.
      • But if you look closer, you will also see that we are making constant steering input changes. We couple the rocking motion with constantly changing steering input that makes a subtle left-right snaking motion as we roll forward. The steering input is small in general, but if you watch, you will see the handlebars turn while the front wheel slithers back and forth along the road, even if you are riding in a straight line. I mention this, because we need to review the difference from that riding outside, the way we use typical rockers, and the way we use the E-Flex. I will cover that in a separate section.
    • Actual Rocking Function Evaluation: With that out of the way, on to the actual evaluation.
      • Once I reconcile the difference in direction of handlebar input, standing efforts are decent. You can get into the right timing and rhythm with a bit of focus initially, and it becomes more automatic in a short time.
      • Seated efforts are easy, and only require a loose grip and support on the bars. Keeping loose allows the bike to find a natural timing with the seated lean and pedal circle.
      • Overall, it took minimal effort or attention to take my hours on other rockers and adapt to the differences in the E-Flex motion. The biggest issue for me was the leveling force which I expand on next.
    • Rocking Leveling Spring Force:
      • Due to my years of use and experimentation with different rockers, I have settled on liking a fairly loose setup for them. It allows a more natural standing movement and keeps my seated movement fairly active. Low leveling force is more like what we get outside, with the minimal centering force from the bike rolling forward and the geometry of the head tube angle, fork offset, wheelbase and other factors.
      • I am also around 150 lbs (60 kg), which means I can get away with less leveling spring force compared to heavier riders. So keep that in mind with the observations below.
      • Based on that, I found the leveling action of the default steering o-rings to be stiffer than I like. This setting keeps the movement while seated to a minimal amount for me. It also makes the standing efforts require significant handlebar force input to get the greater lean angles that I like.
      • That said, I suspect this setting is actually a good option for first time rocker users, and will likely satisfy many users for their entire use.
      • You get a slight rock while seated and keeping a loose grip on bars. The loose grip is key, since any lean is accompanied with a steering of the handlebars. The connection is direct and unavoidable, so keep that in mind. Lean = steer and vice versa.
      • You can get a decent rock while standing, but it takes more force than what we use outside.
  • Fore-Aft Movement (Front-Back Translation):

    • I built DIY motion rollers years ago (inspired by the Inside Ride ones) and used them for the better part of a full season. For rollers, the fore-aft motion is so helpful and makes the overall roller experience so much more satisfying. To date, my motion rollers are the closest feeling that I have had when compared to riding outside. I suspect a good bike treadmill might improve on that, but I have not had the opportunity to try them yet.
    • I also built a test mule rocker plate that included a fore-aft function a couple of years ago. It took what I liked about rocker plates up to the next level and even closer to my motion rollers. All that gets to me liking the concept and function of fore-aft motion.
    • Unlike rocking, the point of fore-aft motion is not to “make it move”, but more to “allow you to move”. Despite our best efforts to ride and pedal smoothly, the human body in motion on a bike is not “perfectly balanced”. By that I mean we have mass in motion (muscle, tissue, bones and such) and even though we are pedaling clean, the mass is constantly moving and changing directions. This leads to subtle force happening all the time. Riding on a fixed trainer hides these shifts in mass.
    • Fore-aft motion simply creates a linear degree of freedom, with a centering force to get back to a neutral point in the range of motion. It allows the upper portion of the rocker, trainer, rider and bike to shift in space. That system shifts as a response to the mass motion. Fore-aft motion allows the shifts to be seen, and we can use these shifts as a sign of our smoothness or lack thereof. Tweak our inputs a bit and see how the f-a motion adjusts.
    • The E-Flex can show varying amounts of fore-aft motion. It is highly dependent on the rider, power level, pedal circle smoothness, upper body control and stiffness and such. You can quickly switch from minimal fore-aft movement to a lot, just with subtle changes in the process.
    • Seated Fore-Aft Movement:
      • For “normal” riding at reasonable power and cadence, the movement is minimal. Likely around 1” or so total shift. Get a bit sloppy, jump on the power or cadence, and there can be larger shifts.
    • Standing Fore-Aft Movement:
      • When we transition to standing, this creates a large shift in the center of mass. It comes up, but the forward shift is the most important here. We tend to pull on the bars and move our hips forward from the saddle. This results in a rearward shift of the bike, trainer and E-Flex. It is not unlike the shift that happens when riding outside. Notable in a group situation as people standing may inadvertently bump their bike back into riders behind them, if they are too close.
      • Stabilize the standing pedaling and the E-Flex comes to a middle point with a larger range in motion than when seated. Maybe 2-3” depending on cadence and power.
      • Transition back to seated and you get roughly the reverse of the transition above. This all depends on the rider, their speed and smoothness of movement, as well as the forces applied to the bars, pedals and saddle.
    • Overall, I found the fore-aft centering springs are quite firm. Much more so than any testing I have done on my own rockers. It is so firm, that I ended up with an odd oscillation in low cadence standing 60rpm. I also got them anytime I had an odd pedal to handlebar timing.
    • I had more than one case where I had a rhythm ,then it slipped a bit (not sure faster or slower) but I ended up getting out of phase enough that it caused a notable drop in my cadence and very odd feeling. This may be entirely my fault, from poor inputs in power and or forces applied. But I still hit it even when I was trying to keep it from happening.
    • I had a theory that the fore-aft centering force was stronger than I wanted, and test that below. As is, I think the f-a is OK, but may be a place to consider for adjustment depending on the rider size and practices.
  • I took notes on the feelings for motions in both directions and started to form a plan for making changes and retesting.

My Modifications:

  • Fore-Aft Centering Spring Force:
    • I wanted to reduce the force and after reviewing the assemblies, I decided the front was the right place to start.
    • I completely disconnected the front Fore-Aft Centering Springs, from the middle connection on the slider. I just shifted the slider, pulled the o-ring off the mount washer & spacer under the slider, and slid it to the edge of the frame, so it would not contact the center slider.
    • Now, all of my F-A centering forces are controlled by the rear section o-rings.
  • Steering-Leveling Spring Force:
    • I wanted to reduce the force, but also the progressive nature of the Steering-Leveing Springs. After review, I decided adding length between the middle o-ring mount and shifting it closer to the pivot axis would drop the spring force, and flatten the leverage rate a bit.
    • I added some S-hooks to the mount washer & spacer under the steering lock. These moved the connection point roughly 1” closer to the pivot to reduce leverage, and shorten the effective eye-to-eye length of the contact point about 1” as well (totally estimating these values from memory, and can document better distances and pics to show the changes later).

Second Ride:

  • Leveling Spring Force:
    • I do a test where I push the saddle fully right, and watch to see how it rebounds and how long it takes to stop rocking. With my rockers, it takes a minimal force (guessing 15-20 lbs side force pushing the saddle) and it rocks back and forth for quite a while before stopping.
    • The original setting on the E-Flex shows higher force and much shorter rocking time in the test above.
    • Repeating the test after the change to the o-ring connection and leverage rate were just what I wanted. The leveling force is much lower, and less progressive in the travel. It allows the bike to wobble back and forth much more like my other rockers
  • Rocking Input:
    • It makes the rider have more control to keep the bike balanced since the leveling springs are providing less support, which is what I want. I can still ride seated upright, with no hands on the wheel to eat, drink, blow my nose, and anything else I do on my other rockers.
    • It also makes the standing effort and steering input much lower force. The motion angle is still interesting, but the force is much better for my taste. It is a more realistic effort to get the rocking vs the very still default setting.
    • It is all much smoother in and out of the saddle, with a clean feel that is what I want.
    • Fore-Aft Motion:
    • Cutting the f-a centering force roughly in half made a huge difference. The return forces are more gradual, without the “snap” that seemed to get me out of phase during the initial test.
    • The forces are much closer to what I tested before, and I have no complaints with the single setup of springs.
  • Overall, the changes I made get this almost right for my needs.

Comparisons to Other Rockers and Outside:

  • Now that the turning the handlebars for rocking is easier, the amount of input is more notable to me. The handlebar turn movement seems excessive for a steer to lean angle (ratio) compared to lean and turn outside. I will call the E-Flex a 1:1 ratio (but that is totally made up and not analyzed). The issue I have with the E-Flex is that it takes lots of handlebar steering angle input to get what I like for a roughly 5* lean angle while standing.
  • As mentioned above, riding outside leads us to add some steering while rocking. I suspect the steering is roughly half of what we see on the E-Flex when it comes to comparing steering input vs actual rocking angle from pushing the handlebars up/down.
  • That leads the E-Flex to feel a bit off to me when doing the standing efforts since the direction and amount of motion is not quite like what I think happens outside. I plan to try and capture the lean angle to steering angle to rocking angle inputs/outputs, to put some numbers to my theories. But I think we will find that a mix of steering and pure leaning take place.

Wish List:

  • Before I get to things I’d like to see changed, I want to say that with the modifications above, the price I paid and the results from the 2nd ride (as well as a few more since then) lead me to be happy with my purchase of the E-Flex.
  • At stock build, I suspect it will meet the needs of most riders. They have an amazing platform that achieves the main goal of adding motion in two directions. It is done with professional build quality and feel.
  • The main point I would like to see changed is the ability to make adjustments to spring forces.
    • I think alternate attachment points for the springs, to allow at least 3 different settings would be beneficial. I know not everyone will want what I like, but I think there is room to have something like mine, the current setting from IR and something in between. Ideally, a more finite adjustment would allow very custom tuning, but could be more complex than is necessary or cost effective. Adding a few attachment points to reduce the o-ring stretch are a relatively simple option, but not the only one.
  • The next point I would like to see changed, but need to experiment with to learn what I really want is the inputs for rocking action.
    • I think the steering direction as the only input for rocking is lacking for the E-Flex.
    • I also think the pure up-down direction as the only input for regular rockers is also lacking.
    • Ultimately, I think a blend of steering input (E-Flex) and tilting input at the bars (regular rocker) will be a feeling that more closely mimics outside riding.
    • I plan to make a test with the E-Flex by modding the base to allow around 3* of rocking on its own. It will be spring leveled and half the travel of my other rockers. My hope is to have this “regular rocker” part as the main activation for the seated rocking.
    • Then it will also assist while standing, and allow for less steering action to get a fuller range of lean. No idea how it will work, but I think this is one of those instances where both sides have it right, and also a bit wrong. A hybrid of the two controls and motions may well be the right mix.

New info about my fulcrum mods:

I completed the initial testing on the stock E-Flex. Then I started modding I covered the “normal” mods with spring force adjustments in the long post linked above.

I have been testing another mod for weeks and pretty happy with the results, but have more to play with to fine tune performance.

Effectively, I closed the open C-shape of the front base, by adding a 1" x 2" board across the rear section. Then I added a piece of PVC tube directly under the middle of the front and rear supports. This elevated the base a bit, and created a fulcrum where the entire E-Flex front section pivots left to right (roll axis rotation). Finally, I added my original foam springs under the outer parts of the rear bar, to act as leveling springs for the new pivot motion. This change offers about 3* of lean with no steering input from the E-Flex.

This allows the entire front section to pivot left and right, like our existing rockers. I call these “plain” rockers, since they tilt left and right by pure force input on the left and right of the rocker. As noted, the E-Flex uses steering input at the bars to cause tilting. So I have created a hybrid rocker that includes pure balance with steering input. It comes much closer to matching the input/output that I feel when riding outside.

  1. Seated, I can lightly rock the bike left and right with not steering input. That requirement to still have steering input for small rocking (less than 3* lean) seem odd to me and doesn’t match what I feel outside. So my mod allows non-steering rocking with simple left-right balance inputs at the bars and saddle.

  2. Standing, I can combine the steering input from the E-Flex along with the shorter travel rocking from the new fulcrum. It feels way better for me to reach the normal 5-6* lean that I use when standing. It no longer forces me to turn the bars super far with what feels like way more turning than I apply outside. I get a nice mix of the steer and pure lean force control and like the result overall. I still need to play with spring rates and total travel allowed with each control direction.

I will note that this setup gets even closer to what I experience riding my motion rollers. I can still ride seated, upright with no hands, but it takes way more focus and early attention to balance to keep from flopping over. It is a result of my reduced E-Flex steering springs, and my relatively low force on the fulcrum leveling springs.

I freely admit that my setup right now is likely at the very fringe of rockers. I suspect most people would hop on and flail around and not feel right. I plan to throw some friends on just to see.

Point being, I am continuing my silly search for the “perfect” rocker and am likely well outside what is needed or even wanted by most people.

The E-Flex in stock form is one of the best rockers I have ever ridden. At it’s price, and if you own a Kickr, I think it may well be the best purchase to be had.


Wow! Thanks for the thorough review and suggestions. I will drill down on the changes you made/suggest and try them on my E-Flex.

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Get that in video McCheeseNuggets! That’s a lot of great analysis that requires another coffee for me to get through.


Chad, I was thinking about getting one. After reading through your review. I am definitely getting one.
Plus who needs DC and Lama now :sunglasses:, Chad has this covered :slight_smile: :+1:

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Appreciate the thought and I totally agree. A video is really needed.
I may see if I can hammer something out this weekend.

Plenty of it really belongs in a separate discussion about trainer motion overall. But I added it here as the first place I have publicly shared some of my concepts. It relates to my take on the function of the E-Flex, so very relevant too.

I will sure see if I can get something into a video, and keep it to 10 mins max if possible, because I know it will be better received than the book above :stuck_out_tongue:

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I agree. +1 on this. And given the way the owner/CEO took aim on here at me last week, with an attempted anonymous post belittling what I do, there’s little chance you’ll see me cover their products.

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Thanks for the props, but we really need more people testing and discussing these motion platforms. Ray, Shane, Tariq, me (if I can make myself put in the time required) and others are all offering useful feedback to users and hopefully manufacturers.

These devices are so relatively new and divergent in build and function, that I think more viewpoints are very beneficial. The DIY roots are leading into larger production, but I think we are still short of what I want to see for a better performing trainer system.

I want more exposure, discussion, critiques, and hopefully improvement in this area. I think it’s the next frontier for indoor cycling and training, and we need more people to help get it where I’d like to see it.

That was a lame post (group of posts really, when you look back a bit) on his/their part and quite shady indeed. I saw it and appreciate that Ray finally called out the questionable posting. It has no place coming from a manufacturer.

I left any mention of that out of my review, but the taint that has from a broader perspective does color my overall take on the company’s practices.

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Lama, your reviews are trusted and well worth every minute. Chad did an AWESOME JOB on this, he’s always been a rocker guy and “the MAN” on the Forum. I still think you should review one. Two or more heads are definitely better than one.

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This won’t be happening.

Wow that required all of lunch to read! Great stuff.

For those looking for more of a bottom line, as a “never had a rocker plate” guy I’m going to amend my earlier review and give updated impressions:

  • prior experience was putting inflatable balls under feet of Kickr, didn’t like that and removed them
  • unable to make time to build my own rocker plate due to family, home projects and training
  • E-Flex was easy to setup, ride, and store
  • its kinda like riding outside, kinda not
  • short adjustment period, and no learning curve
  • forward/backward motion helps identify sloppy pedaling
  • my butt still gets sore after 60 minutes on the trainer
  • E-Flex makes riding on the trainer better, but nothing beats outside and I live in California so trainer has been put away until a rainy day comes along and my butt is happily logging 8+ hours/week outside
  • would I buy again? Yes to both E-Flex and Kickr 2017 direct drive

I was really happy with InsideRide until seeing @GPLama post today about the pissing match (yes, I went and found it).

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Chad, you mind posting some pics of some the of the mods you did? Curious to try them myself. Removed the front “spring”, but couldn’t figure out the side to side mods you did. Sounds like you just removed the “springs” and put s hooks onto them thereby reducing the tension on them? Thanks.

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Here is what I can add quick. I can go into more detail later, and happy to answer questions, and catch a video in the near future.

1" x 2" x 28" board to close the open “C” shape of the lower frame.
2x PVC pipe mounted with hose clamps to create a new fulcrum.
2x closed-cell foam rubber stacks for leveling springs.

Any recommendations on the best thru axles to get to use with this? (i.e. easy to screw in and unscrew)

I’m using a Robert Thru Axle and long hex wrench.