Truck Information

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RandalAnatomy.B.H.jpg

Angled Risers

Angled Risers will help give the trucks a slight angle which helps to make the board carve better; however, if your board already has a wedged nose or tail (also see Contour), then you will most likely not need angled risers.

This chart will help out you out in finding the ideal angled riser setup for your style.

Wedges.B.H.jpg

Axle

This holds the bearings, which hold the wheels. Typically comes in 8mm or 10mm diameters.


Axle Offset/Rake

This describes the axle’s position compared to the pivot axis. This is also referred to as the Caster Angle.


Axle Travel

This is the path the axle takes when it rotates on the pivot axis.


Axle Width

The distance between one end of the axle to the other (also known as Hanger Width)

The number one question to help you decide which width to pick is: How wide is the board? You should usually try to match the outside of the bearings with the edge of the board where your front foot is. This will provide you with good leverage over the hanger.

However it's usually better to have a hanger that's a little too wide, than too thin. Significantly too thin can cause the outer wheels to lift when turning.

People often describe a thin hanger as being quicker turning. This is because the board usually has more leverage over the hanger, the wheels travel a shorter distance to get to an angle, and less board-lean is lost to bushing compression.

It's not uncommon for people to deliberately choose to increase their board's leverage by choosing a thinner hanger than would usually be advised.

People often describe a wide hanger as being more stable. This is because the board often has less leverage over the hanger, the wheels travel a longer distance to get to an angle, and more board-lean is lost to bushing compression. Plus your feet usually have less leverage when compared to the board, and the wheels create less steering when they go over bumps.

It's not uncommon for people to deliberately choose to lower their board's leverage by choosing a wider hanger than would usually be advised.

When the axle angle is the same, the board turns on the same axis, regardless of hanger width.

HangerWidthTurnCompW.jpg


For street-luge and buttboard wide hangers are always recommended, using a significantly narrower hanger can actually cause the board/sled to roll when turning.

Notes on Width:

As stated above the width of the hanger doesn't affect the turn radius when the hanger is at the same angle. But if the bushings are the same it takes more force to get a wide hanger to that angle, which is good for stability, but bad for responsiveness.

A wider hanger is often compensated for with a softer bushing, this can lead to some board angle not being converted to axle angle or "lost to squish", and to corner forces shifting the hanger left or right on the kingpin. A wide hanger can potentially be more prone to wheel-bite, as the wheels get closer to the board at the same lean. A wide hanger can also sometimes put the wheels far enough clear of the board to make wheel-bite impossible. A too-thin hanger can be compensated for (to a degree) by soft/loose bushings. There is a limit though. The shape and core of the wheels can have some effect on what hanger width is optimal.

Baseplate

This bolts to the board, it in turn holds the kingpin and pivot-cup.


Bottom Bushing

Made from polyurethane, it helps hold the hanger in place and control turning. The bottom bushing also takes rider weight.


Bushing Seat

This part of the hanger is shaped to help the bushings keep the hanger in the right place.


Caster

Positive Caster is the tendency for the truck to stay centered. Negative Caster is the tendency of the truck to stay in a turn. This is determined by the axle offset being either above or below the axle.


Cup Washer

These help push the bushings into the hanger’s bushing-seat. The washer shape helps control the shape of the bushing’s distortion when the hanger turns. If you have a cupped washer, the amount of lean over your trucks (in order for them to turn) is limited more than if you used a flat washer. Cup washers also help increase the reaction time the board has to return to center.

Flat Washer

The washer shape helps control the shape of the bushing’s distortion when the hanger turns. If you have a flat washer, the amount of lean/leverage over your trucks is limited less than if you used a cupped washer. Flat washers also help decrease the reaction time the board has to return to center and allow for a smoother carver action.


Flipping Hangers

Flipping the hanger involves undoing the kingpin, taking the hanger off the base-plate, turning it over and bolting it back together.

RandalFlip.B.H.jpg

This only works with some hangers, it requires an axle that is offset from the pivot-axis, axle offset is also commonly referred to as rake and caster.

But what does this do?

The short answer is that it lowers the ride height and can help increase stability. The long answer is that it also does the following. 1. Lowers the ride height. (Check for wheel-bite before riding) 2. Increases the axle’s up-down leverage over the bushings. 3. Changes the behavior of the axle’s torque leverage over the bushings. 4. Moves the board’s centerline, relative to the wheels, when turning. 5. Moves the roll-axis of the board. 6. Moves the axle further from the pivot. 7. Slightly reduces the distance between axles. It does not change the pivot-axis angle. It does not directly reduce the board’s leverage over the bushings, but it does change the hanger’s resistance to lean...

How do I tell what side I’m using?

The width markings can identify the different sides of R2 hangers, 125, 150 or 180 is cast into the front of the hanger. When this marking is easily visible the hanger is in its standard/ un-flipped state. The F and R markings on Luge hangers identify the different sides. The R is the regular side (sometimes referred to as response) The F is the flipped side (sometimes referred to as fast) The 160mm downhill hanger and the original Comp 1 hanger both have no axle offset and are not intended to be flipped.

Mixing Base Plates?

Any Randal hanger can be put on any Randal baseplate. This is possible because the hangers all have essentially the same pivot to bushing seat measurement. This can allow for a high level of customization, as riders can choose any hanger width and pivot axis combination they want. Some riders prefer the feel that can be provided by a high angle front truck and a low angle back truck. It's an effective way of providing stability to the tail without sacrificing too much turn radius. But it does produce a board that rides strangely going backwards.

Doing it with different baseplates rather than wedges keeps board height down. This is possible because all Randal baseplates and hangers are interchangeable.

Notes on mixing angles

When the bushings are the same, a lower angled truck requires less force to make it lean. This can lead to the front outside-of-turn wheel lifting, which is bad for traction. The fix is to run harder/tighter bushings in the tail, and/or softer/looser bushings in the front. Here is a chart to help in determining the overall ride height of the truck based on hanger and baseplate combinations.

Hanger height chart.jpg


Here is a compatibility chart of which hangers fit on which baseplates.

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Hanger

The hanger holds the axle, the bushings and has a pivot. It’s width controls the distance between the truck’s wheels.


Hardware

The bolts than hold the trucks to the board. There are two types of bolts. Recessed bolts are used on Top mount boards. These fit down into a board with recessed holes and are measured from end to end.

Machine bolts are typically used on Drop Through mounts. These are paired with washers. Measuring these are from under the head to the threaded end.

Standard hardware: #10 with 32tpi (treads per inch) mounting bolt is imperial/SAE, not metric. It's also not UNC threaded.

When nuts are frequently removed and reinstalled, the nylon thread lock material on the threads wear down and could result in loosing a nut and possibly a wheel. It is a good idea to use a thread lock compound on the bolts to reinforce safety.


Kingpin

This bolt holds the truck together as one unit. How tight it is affects how the board turns.

It's possible to use most 3⁄8"-24tpi bolts of suitable length as a kingpin. Just make sure you use grade 8 bolts, identified by six lines on the head.

Some people advocate using the kingpin with the nut on the hanger-side of the truck. With longer bolts, make sure that this doesn't put the kingpin where it can hit things on the road.

Grade8Head.B.H.jpg


The difference between grade 8 and grade 5:

Grade 8 bolt capability in yield (stretch) = 130,000 lbs / in2 x .03349 in2 = 4354 lbs minimum Grade 8 bolt capability in tension (failure) = 150,000 lbs / in2 x .03349 in2 = 5024 lbs minimum

Grade 5 bolt capability in yield (stretch) = 92,000 lbs / in2 x .03349 in2 = 3081 lbs minimum Grade 5 bolt capability in tension (failure) = 120,000 lbs / in2 x .03349 in2 = 4019 lbs minimum

It's typically a bad idea to run a kingpin flipped for it can cause major wearing within the baseplate. This can cause slop because the kingpin is much harder than the soft cast aluminum. If your kingpin has slop, you can shim it with a piece of coke can.

Pivot

Part of the hanger, it helps hold the hanger in place, as well as constrain it’s motion to the pivot axis.


Pivot Angle

Determined by the trucks Pivot Axis

At the same wheelbase, a higher angle pivot-axis will create more steering per board-lean than a lower one.

This generally makes the high angles more suited to turning, the low angles more suited to speed. However high angled Randals are still exceptionally stable for how well they turn. And low angled Randals are a great way to keep board length down, without sacrificing stability.

How is the angle measured? Randals can be accurately described by either the kingpin angle or the pivot-axis angle, because the pivot-axis and kingpin are at 90° to one-another. You just have to measure them from different places.

RandalAngles.jpg The wheels of high angle trucks move in-and-out more than low angle trucks, which have a more up-and-down motion. This difference can affect the correct position of wheel-wells. And along with wheel-size and hanger width affect the size and shape of cutouts.


LeanComp3.jpg

The above illustration also clearly represents how low angle trucks create much less turn when compared to high angle ones. (When the board lean angle is the same).


Notes on angle:

It should be noted when comparing trucks that not all companies use the same method of measuring their truck angles. For example a 50º truck could be called 40° (90-50=40) if it was measured differently. The further above 45° the pivot axis is, the more downward force is required to make the hanger turn, to the point where, at 90°, it is impossible to turn the hanger with the board. Conversely, the closer to 0° you get, the easier it is to lean. This is assuming the bushings, tightness and board-width remain constant

Pivot-axis

This is what the hanger rotates around when it turns.


Pivot-cup

Made from hard polyurethane, it holds the pivot in the correct position.


Risers

Risers are hard or soft plastic rectangles which rise the board so wheel bite is less likely to occur. Typically, more leverage is increased allowing for harder turning. Generally, risers are referred to the hard plastic kind. Also see Soft Risers


Roll-axis

This line is what the board rotates around when it leans.


Roll Center

Defined by where a line, square with the board, crosses both the axle’s center, and the pivot axis. A line between these points on both trucks defines the roll axis.


Shock Pads

Typically made of rubber and differ from riser pads. They reduce the vibrations transferred from the road to the rider's feet. They are commonly referred to drop through mounting, which consist of two per truck which are mounting between the top of the board and baseplate.


Soft Risers

Soft plastic rectangles or rails which rise the board so wheel bite is less likely to occur. Soft risers reduce road vibrations better than hard plastic risers.


Spacers

Placed between bearings within the wheel, these allow the wheel nuts to be tightened completely. They also reduce wear an tear on the bearings caused by sideways loads of sliding and carving. Typical sized spacers come in 0.400" width (aka 10mm).


Speed Rings

Also called Wheel Washers, go on the outside of the bearings, between the axle nut and hanger.


Top Bushing

Made from polyurethane, it helps hold the hanger in place and control turning.


Track Length

The overall length of the axle width combined with the lips of the wheels.


Truck Facing

The end of the hangers, where the axle protrudes from the hanger, are smoothed out. Facing improves traction, increases bearing life, and reduces noise.

Wheel Nuts

Nuts that hole the wheel on the axle.