APEX AIR & PKP TUNING MEGATHREAD

Introduction to APEX AIR & PKP

APEX AIR are the first Parallel KingPin trucks on the market that have been designed from the ground up with E-MTB in mind. They use Riptide™ Krank® bushings which allow a huge amount of tuning possibility. But there’s a lot of things you can adjust . . .

We Have been riding these trucks and experimenting with different busing setups for a while now and every day we’re still discovering/testing new concepts, ideas, and combinations. The most exciting thing about these trucks is the number of possibilities that it opens up and we’re only scratching the surface of whats possible. We fully expect the creative minds here to think of things we have never even considered yet.

The goals of this thread are as follows:

  • Show the concept behind PKP trucks.
  • Give a short explanation of terminology to use when discussing PKP trucks
  • Primer on Riptide™ Krank® bushings
  • Explain some PKP tuning concepts
  • Share our recommended setups and what our testers are currently riding.
  • Open the thread for discussion.

We want to create a productive and on topic place where everyone can get an understanding of how to get their setup just right and a place where you guys can discuss what you have found to work for you.

With that said, lets get started.

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PKP Terminology

We’re going to start basic here to make sure everyone is on the same level.


Components

Baseplate - The part that bolts to your board.

Kingpin - Traditionally this is the main bolt in the center of the truck. The PKP truck has 2 kingpins that are mounted in parallel to each other. They slide into the baseplate from above.

Hanger - The main moving part of the truck. On a PKP this has no solid coupling to the baseplate so may be referred to as a “floating hanger”.

Bushings - On PKP these act as the main interface between the hanger and the rest of the truck. They control every aspect of the ride feel.

Cup washers - Keep the bushings central on the kingpin and stop them slipping around during riding.

Kingpin Nuts - Apply pressure to the bushing and hanger assembly. They can be adjusted to set preload on the bushings.

Axles - Screw into the hanger and allow the wheels to be mounted.

Grub Screws - Are used to secure the Axles in place

Axle Spacer - Keeps the wheel bearings correctly spaced away from the hanger. On some electric setups this will be replaced by drive mounting hardware.

Axle Nuts - The nuts that hold hold the wheel on.


Features and Geometry

Bushing Seat - The part of the hanger that the bushing sits into.

Pivot Axis - Whilst the PKP truck is able to rotate slightly on all 3 axis, the dual sets of bushings constrain this movement to be predominately in one axis. This is called the pivot axis and it goes directly through the center of the bushing seats, front to back, parallel to the board.

Pivot angle - This is the angle between the pivot axis and the ground. As with many other channel trucks we have been using a pivot angle of around 35 degrees.

Axle Offset (sometimes called Rake) - This is the distance between the center line of the axles and the Pivot Axis. Apex Air has a positive axle offset like many other channel trucks (The axle sits below the pivot axis).


Bushing Positions

On the PKP Truck there are 4 bushings on each truck. When discussing bushings we will use these names for their positions.

Road-side Bushings - face down toward the road.
Board-side Bushings - face up towards the board.
Far-side Bushings - On the kinpin furthest from the rider.
Near-side Bushings - On the kingpin closest to he rider.

Traditionally the road-side bushing is called the “top bushing” despite being on the bottom whilst riding. Similarly the board-side bushing can be called the “bottom bushing”. We found this gets confusing so prefer using road-side and board-side as they are easier to remember.

When discussing setups a single bushing can be specified with both terms eg. “I use a green cone on the far roadside bushing”.

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Riptide™ Bushings.


Formulas

Riptide™ have 3 different formulas used in their bushings and each has different properties.

  • APS™ Formula: Animated Polymer System.
    As the name implies, This compound is very lively and offers high rebound with lots of control and lean.

  • WFB™ Formula: World’s Fastest Bushings.
    This compound offers reduced bushing friction for fast transitions and a deeper lean than the APS. WFB also offers lower rebound than APS and is designed for the rider that wants a very fluid response.

  • KranK™ Formula: Performance Under Pressure
    Riptide’s highest rebound formula to date, KranK is designed specifically to change under pressure and is controlled by the amount of clamp pressure you subject it to when tightening the King Pin nut! The effective range of control is from barely snug for the loosest feel to 2 full turns for the tightest feel.

During development we have been working closely with Riptide™ who has suggested that the KranK™ formula would be the best choice for the PKP due to its large range of adjustability by varying the kingpin pressure.

Because of this Apex have only been testing with KranK™ formula bushings and we will supply these as the standard bushing option as well as keeping stock in our store.


Bushing Shape

The bushing shape controls the relationship between between the lean angle of the truck and the amount of force required to produce that lean angle. Its what controls how linear or progressive a turn will feel.

We have been testing KranK™ bushings in the 4 standard shapes.

Cone

The cone shape has the lowest resistance and stability of all the shapes and can allow your trucks to easily achieve their full lean and turn without loosing the feel of the truck. On PKP this results an a super carvey setup that feels like no resistance is added the more you lean, similar to DKP trucks.

Barrel

The barrel shape offers the next step up in stability above cones. On PKP these seem to give a very liner feeling where the more you lean the more resistance you feel and the more force is required. This is the type of response that feels familiar if you’ve ridden barrels or shockblocks in the past.

FatCone

The FatCone shape has the same initial stability as a barrel but as you lean they offer a progressively higher resistance. On PKP these can be used in high speed carve setups where pushing hard into a carve will give a lot of resistance improving stability.

Chubby

The chubby shape offers the highest stability of all the shapes. They still turn very well and can be used in a softer durometer If you are looking for a stable yet plush and comfortable setup.

Other shapes

There are a few other shapes such as the canon, magnum and some different height variations of the above shapes however we have not tested these and cannot guarantee compatibility.


Bushing Durometer

The KranK™ bushings come in 5 durometers.

Orange Red - 84a - Softest
White - 87a - Soft
Green- 90a - Medium
Wine Red - 93a - Stiff
Grey - 96a - Stiffest


Preload

The main advantage of the Krank formula is the ability to tighten the kingpin nuts and preload the bushings.

Getting “SNUG”

When the kingpin nut is too loose you can easily turn the cup washer with your fingers. As you slowly tighten the nut you will reach a point where the cup washer becomes more difficult to turn. Stop.

Riptide call this point “snug”. This is the minimum recommended preload for the bushings.

More than Snug

By tightening the kingpin past this point you are preloading the KranK bushings, adding additional resistance. Go easy as a little preload makes a big difference.

Riptide recommends a maximum preload of “snug +2” which means 2 full turns of the kingpin nut past the point of snug.

Remembering this preload number will be useful if you frequently switch between different bushing sets that might require different preloads.

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PKP Tuning

These are some things we had discovered during our testing. Some obvious, some not so much.

Mixing Bushings Colours

When turning both bushings get compressed, so if your running different durometers roadside and broadside you get a feeling that’s in between both duros.

Mixing Bushings Shapes

You can mix and match bushing shapes to get the best qualities of both. For example the responsive cone and the progressive fatcone work great together. This can be useful if you want a specific bushing on one position such as larger bushing board side.

Board-side controls Shock absorption

Whilst riding, all your weight is resting on the board side bushings. This means that running a softer boardside bushing allows the truck to absorb more bumps and gives a smoother ride. All our APEX stock bushing sets use a softer boardside bushings.

Softer bushing mean less resistance when turning but you can compensate for this by using a larger bushing like a fatcone to give more resistance. Alternatively you can increase the hardness of the roadside bushing.

Angled risers

Bigger pivot angle means you get more turn for less deck lean. For eMTB the sweet spot seems to be around 35 degrees, this means that some decks like the Bro work best with a 5degree riser.

We’ve never tried it but there’s probably some interesting split angle configurations possible for super stable street riding.

Diagonal pairs

This is still experimental but some early research shows that having different durometer bushings in a diagonal configuration can make the trucks more or less responsive. Stiffer bushings in the far roadside and near board side sharpen the turning (similar to increasing the pivot angle). Moving them to the far boardside and near roadside can dull the turning.

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Apex Recommended Setups.

We have 3 main bushing sets that are available to purchase with the Apex Air and will also be available separately.

All of these sets use a fatcone & cone combo. We found this to be a well rounded combo that feels similar to what riders are used to from other channel trucks.

All our sets also feature softer board side bushings to give you that bump-free AIR feeling.

Medium Bushing Pack

Orange red fatcones board side and green cones roadside. This is the default and recommended bushing set for most riders. Its a the best option for getting started. This soft but stable setup is ideal for riding street and mixed terrain.

Soft Bushing Pack

Orange red fatcones board side and white cones roadside. This set is for lightweight riders who want a carvey feel for riding street.

Hard Bushing Pack

Green fatcones board side and wine red cones roadside. This set is for the hardcore riders who plan to “send it” at 30mph through the forest and off huge jumps.

Recomended Extras

Riptide™ Krank® Barrel and Cone Packs

We found that having a few extra cones and barrels opens up a huge number of combinations when mixed with our standard bushing sets. You can use these with your existing fatcones to get stiffer / softer and experiment with different front rear setups. Or use them with your existing cones to achieve much more carvey setups.

Were stocking these packs in 84a, 87a, 90a, and 93a Variants. The packs are easiest way to get a lot of additional options quickly.

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RESERVED - To share our test riders preferred setups

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RESERVED - For any future concepts discovered by the community

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RESERVED - To feature any clever user setups

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A lot of information in the above posts posts but the science is just beginning.
We expect the information here to develop and evolve over time as new discoveries are made.

We want this to become an active discussion and place to share information so we encourage everyone to get involved.

Feel free to ask any questions you may have related to PKP tuning and please share your setups and experiences with us.

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Well done @ducktaperules !
Hope I didn’t missed it out somewhere in between the lines, but I would like to add that the preload as well influence the truck response and over all ride feeling.
I personally prefer softer bushings with preload over stiffer bushings totally loose.

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this is a great point and i will make sure that is in there somewhere.

Im also preferring softer setups with more preload.

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@ducktaperules excellent job dude! This thread is awesome, and I love how you formatted it. There’s tons of useful information in here, even for folks like me who can only dream of one day being able to afford Apex Airs :joy:

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Yeah a lot of the info about the Riptide bushings should be usfull for anyone running TKP, RKP or DKP trucks too.

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So the axle is directly in-between the bushing seats more or less?

I’m trying to think which bushing is predominantly taking the bodyweight load, traditionally your boardside bushing is a little harder to support rider weight. Obviously here both boardside bushings are taking up some of it, but because of the axle location and mounting angle weight is going to go towards one more than the other.

Wonder if there’s any scenarios where you’d run two different boardside bushings because of this.

One of the hypothetical limitations of this family of trucks is that you’re relying on the bushing seats to limit rotation outside of the pivot axis much more than on a traditional kingpin truck. I’ve never actually touched one, but I presume that you have a trade of appearing between precision turning and degree of lean based around how restrictive the bushing seat is. Is this something that’s been noticed? Any difficulty at all getting appreciable lean without the trucks becoming sloppy?

Have there been any experiments with putting the kingpins out of perpendicular with the pivot axis?
With TKPs, that’s one of the reasons they’re able to lean so much with compact bushings.
There was one of these 4 bushing trucks I saw a long time ago that actually had the two kingpins at 90 degrees to each other, that’s about as extreme as I imagine it can get.

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I‘m definitely going to play with that as soon as I do receive my set of white fat cones.
I think I can get my setup a bit more turnable while maintaining the same stability at speed.

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On apex air the hanger is symmetric and the axle runs in the centre of nearside and farside bushings. However there is positive rake so there is a small offset between the center line of the axle’s and the pivot axis.

When at a 35° angle during normal riding this means that the far boardside bushing carries slightly more weight than the nearside bushing.

Im not sure if this carries over due to the weight being distributed through more bushings but it would be an interesting experiment.

This is a great question. I have not tried a setup like this but it could be possible that running softer nearside to compensate for carrying less weight might soften the ride a little.

At super low speeds a setup that lacks preload feels a little odd but as soon as you reach snug it seems to sort it’s self out.

This is true and softer business definitely limit off axis less but we have yet to notice any issues with this.

It’s hard to explain but off axis “slop” doesn’t feel as you would expect. Bumps that knock the truck off axis are not transferred to the deck, and without constraint from the deck the truck easily jumps the bump and returns to its correct rotation.

Additionally the the reduced inertia of the hanger and means it can bounce and respond much quicker to un even surfaces. But as these quick movements are decoupled you don’t feel them. It’s a strange sensation looking down at crazy vibrations but hardly feeling them.

It’s been discussed, I have designs, and I’d love to try it but this costs time and money. For now our priority is to get these in the hands of users. Once we have funds again we will definitely continue development around this concept.

I would love some details on that if you ever come across it again.

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I don’t even ride MTB and enjoyed reading all the info, GG @ducktaperules!

Just curious, could PKP be a good alternative for DKP on street boards with big wheels?

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Don’t know, it would need to be tested. They would probably be a great option for a larger carver. Never tried them on a smaller evolve style board.

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This is an awesome thread and really shows all the work you guys have put into this. Thank you!

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