Ride hight vs Traction

**SteveC** · 07-30-2007 08:25 PM

Well here's the background.
when you raise / lower a truck you effect where the boards centerline ends up while turning.
The higher you go, the more to the inside the board ends up
This seems to effect traction. It's certainly the evident factor in the reduced traction of dropped speedboards...

The theory is, that it effects the weight ratio between the inside and outside of the board.

Now the questions are.

Do slalom boards have a 'sweet hight'?
Does, or how does it differ from truck to truck?
Is this the real reason splits can have more traction?

**Slim** · 07-30-2007 09:31 PM

Great topic Steve. This is going to get complicated. Maybe we should make some sketches we can refer to. I bet Chris Chaput already has some (he's got such great 3d images for everything) but I'm sure he's way busy. I bet Dan Gesmer also has this stuff all figured out. Anyway, I'm looking forward to the discussion amongst the members here.

**SteveC** · 07-30-2007 10:27 PM

well. heres one I prepared earlier.
It's speedboard specific. unfortunately. (for this particular discussion anyway)

**Slim** · 07-30-2007 11:16 PM

**SteveC** · 07-30-2007 11:31 PM

well it's vaguely accurate...

It's simply showing how the center of the board moves outward the further down you go.
or conversely, inward as you go upward.

I'll do one that represents a split DH truck.
I don't have the .psd here so it will take me a bit.

**Slim** · 07-30-2007 11:36 PM

If the board leans more, then yes. But are you saying that at the same board angle (and thus same truck turning radius), that the center point of the board will be different vis-à-vis the kingpin depending on how high the deck has been spaced above the baseplate?

I had just kind of assumed that any loss in traction in a drop-thru deck was because one had less leverage over the truck and therefore had to put more weight on the edges of the deck to make the turn and that moved the center of gravity of the *rider* more off the center of the trucks than he'd have to move for a top-mount deck to make the same turn.

**SteveC** · 07-31-2007 12:14 AM

**karrot** · 07-31-2007 12:25 AM

Originally Posted by SteveC

well. heres one I prepared earlier.
It's speedboard specific. unfortunately. (for this particular discussion anyway)

can you explain this diagram? it looks cool, but i dont know what it means....

**GoGreenLongboarding** · 07-31-2007 12:42 AM

This makes perfect sense. the boards are all leaned to the same angle so it appears. The red dots mark the baseplates and give you a good idea of where the weight center is, and the blue lines show where the center of weight/baseplate is on a raised board.

this appears to me that it would result in better traction on raised boards to a point (i would speculate that under 1/2 inch of riser is below this point depending on truck type), and (huge opinion coming up) could also explain why drifts feel more controlled on low boards. I would say that because your feet are right near the axle and the rider could be applying weight outward rather than down with little effort.

**SteveC** · 07-31-2007 05:36 AM

**bucksaw87** · 07-31-2007 11:49 AM

Originally Posted by GoGreenLongboarding

This makes perfect sense. the boards are all leaned to the same angle so it appears. The red dots mark the baseplates and give you a good idea of where the weight center is, and the blue lines show where the center of weight/baseplate is on a raised board.

this appears to me that it would result in better traction on raised boards to a point (i would speculate that under 1/2 inch of riser is below this point depending on truck type), and (huge opinion coming up) could also explain why drifts feel more controlled on low boards. I would say that because your feet are right near the axle and the rider could be applying weight outward rather than down with little effort.

same concept as:
riding a topmount and turning; the center of the board stays over the trucks BUT on a dropped deck, the inside wheel gets closer to the board and the outside wheel gets farther away?
(watch your wheels next time you're riding)

**Uncle Al** · 07-31-2007 12:05 PM

By SteveC's diagrams (nice work by the way), a lowered board puts the weight further towards the outer edge of the outside wheels in a turn. Could a wheel be designed to perform specifically around this type of weighting? To me it seems like a sideset wheel with a stiff outer lip would perform well under these circumstances. Just my thoughts....

**El Beefo** · 07-31-2007 04:29 PM

Theory:

From the diagrams, and experience, it seems that most of the pressure during a turn is placed on the inner edge of the inside wheels. Therefore, you will get the most grip if you can put most of your weight on that part of those wheels. When you lower a deck, you are moving your weight further to the outside, and less on the wheels that give the most grip, resulting is less grip overall.

I pretty sure it's mostly about where the weight in a turn in applied, and applying it to the wheels that give the most grip will obviously give the most grip.

**Slim** · 07-31-2007 05:34 PM

Steve, thanks for the follow up earlier. I know understand the phenomenon you are explaining.

**lettucefresh** · 07-31-2007 05:59 PM

All I know is that I can't turn drop-boards for ####.

I'm just going to follow this discussion and wait for shapeshifter, aaron, geezerx, cc, or gesmer to tell us the answer.

**GoGreenLongboarding** · 07-31-2007 06:19 PM

i'll give you a hint, i'm pretty sure i've seen chaput post something along the lines of him not liking boards that are too low... not sure of the exact wording but i think he said he likes his slalom decks to sit high. someone please correct me if i'm wrong, i tried searching but even if you search by user you still have to wade through the whole thread (wtf?)

**Pinhead** · 07-31-2007 08:16 PM

I think a taller deck will put more weight to the outside
wheels than a lower deck durning a hard turn. Think of the
side forces in a turn. Push sideways on a silly high deck
and you could lift the inside wheels much easier than you
could with a drop deck.

With a drop deck you get more of your weight to the inside wheels
and if you slide even more weight shifts to the inside wheels and you slide
even more.

I tried someones small drop deck at a slalom race and was shocked
at the lack of grip with what I knew to be sticky wheels.

**SteveC** · 07-31-2007 08:20 PM

I wish I could think of a simple way of actually testing this stuff.
I guess a device that measures g-forces could be fixed to a board pretty simply.
and would tell you how much a board got to before it let go.
but inside-outside weight ratio.. shrug.

**thebassman** · 07-31-2007 08:52 PM

in a big fancy way is all this saying that drop decks have less traction?

**SteveC** · 07-31-2007 09:03 PM

Originally Posted by thebassman

in a big fancy way is all this saying that drop decks have less traction?

No. That's already evident.
What I'm trying to bend my head around is precisely why.

That knowledge is vital for...
A. Maximizing traction.
B. Stabilizing a board without loosing traction...

on another note. It's interesting that reports people have given of the confederate trucks is that the different bushing positions actually give significantly different performances.
I think it's because the axle has more leverage over the bushing in the lower position. (on all axes save torsionally{yaw and pitch, but not roll})