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| Truck Reviews (15215 Posts)
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Line it up
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On 12/9/2007 PSR
wrote in from
United States
(75.68.nnn.nnn)
Exactly, Herbn. Just where the bushings seat (using 'stock' bushings) in the hanger, and also having the pivot point (or possibly the cup's seating in the baseplate as well) line-up along a different axis (flipped Vs. un-flipped), these things Will Change The Geometry in the pivoting action. This is Without taking into consideration rake, castor, bushing shape, or use of spherical ball joints.
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flipping bear
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On 12/9/2007 herbn
wrote in from
United States
(71.251.nnn.nnn)
i 'm pretty sure you know how thw bears "work", "fake pivoting axis" is ,to me On an indy type truck,the comprimise between the real pivoting axis and the angle that the hanger would pivot on if it could faithfully follow the angle of the kingpin, because the soft mounted, it follows the pivot angle at first(for a few degrees of lean), then it starts to average in a bit of the kingpin angle,for less turning/lean,a shallower angle. A randle type truck steers mostly true to the pivot angle because the bushings are lined up perpendicular. So the confusing Bear,it sounds like if you took randle and bent the pivot knob on the hanger a bit to make it a different angle,47 instead of 50, when you flipped it ,it would be 53 degrees. Neither represents the actual turning angle because you've got that comprimising action going on, but you do have a change in angle. You've got a randle type truck that doesn't really fit together right,it's just like if you took a randal and stuffed longer bushings in to raise the steering angle to 53 degrees, or shortend the bushing to make it sit at 47 degrees.
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grizzly
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On 12/9/2007 hc
wrote in from
United States
(71.198.nnn.nnn)
Herbn, not sure I can decipher what you are saying,
but from their description, it sounds like they are describing the 'fake' steering axis.
"How dose this flipping measurement work? Well, the bushing seat is recessed in the hanger, and the bushing seat and pivot nub are angled. So from the middle of the pivot cup to the middle of the axle is 57 degrees for carving and flipped for downhill it is 47 degrees."
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flipping bear
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On 12/9/2007 herbn
wrote in from
United States
(71.251.nnn.nnn)
if the without the bearing has a geometry arranged like i described in the last postthe angle would change a bit and the fit would be a bit inaccurate but it would "work" and be no worse than mixing parts from different indy stages which lots of people have done most of them swear they fit fine but if you don't believe me maybe belisve donald i think he posted that if you look carefully different stages don't exactly center the kingpin in the bushing seats.
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bear
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On 12/8/2007 hc
wrote in from
United States
(71.198.nnn.nnn)
herbn, I am referring to the cast bear grizzlys.
http://www.landyachtz.com/D27.cfm?PID=285&place=1
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longboard web site under construction.
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On 12/8/2007
paul ireland
wrote in from
United States
(205.188.nnn.nnn)
check out www.thelongboarder.zoomshare.com for some sweet longboard stuff. there is also a skateboard deck for sale on the site too. please note that the website is under construction and will be fully up in about a week. check it out!!!!
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flipping bear
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On 12/8/2007 herbn
wrote in from
United States
(67.83.nnn.nnn)
"simply flipping" the hanger could change the angle if the bearing between the bushings is not cntered on the piot axis bearing ,if both bearings are spherical things would just sort of shift over the part of the truck that fits into the pivot axis bearing(the one in the baseplate would just sort of slide to a new position,the fit on all parts would need to be pretty tight, for this to work. Although the bushings wouldn't be square to their seats,with loose springy bushings it might not be a big deal, it's a more precise version of steepening indys with taller bushings or extra washers between the baseeplate and the cup washer.
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polymorph
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On 12/8/2007 Michael
wrote in from
United Kingdom
(87.114.nnn.nnn)
has anyone any experiance of using polymorph, the plastic putty stuff, to make pivot cups? As it works by heat, does it not work well on a rubbing pivot application, as when dry/moulded it sems quite greasy in the had.
Just wondering if its a pointless exercise.
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fake is fake
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On 12/8/2007 hc
wrote in from
United States
(71.198.nnn.nnn)
psr, look at the diagram again.
SteveC made that diagram for people who incorrectly assume that steering axis is simply connecting axle to pivot, flipped or not!
What you are talking about is what I call
'imprecise steering axis' (just made that up)
due to the nature of the dual-action bushings.
For Randals the bushing seats are absolutely inline with steering axis.
(For Bear trucks, the jury is still out, there are others on SF that also question their claim of steering axis change by simply flipping)
Regarding bikes, just because Peter have background in motorcycles means it relates to trucks? That sounds like a stretch. PVD's are simply solid pivot trucks with some offset. That rectangular bushing is the one piece that is kind of unusual. What's impressive about the truck is more the contruction than anything else.
Regarding Herbn's strokers, now that's what I really want to take a spin on...
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Steering true..
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On 12/7/2007 PSR
wrote in from
United States
(75.68.nnn.nnn)
Actually, the 'fake' pivot line, is real. What you must understand here is that very few truck actually steer 'true' to the pivot point's intended axis line. Rather, what often occurs is that bushing height, washer thickness, that kind of realignment creates a skew in what would otherwise be the true steering axis. With Bear or Randal, you gotta figure in also that the Bushing Seat is NOT inline with this pivot axis, so flipping the hanger does indeed change the steering geometry, and in quadratic math, changes the reactionary speed of input by changing the Castor Angle. Trucks like Radikals that use spherical pivots at the pivot-point (cup) and also in the hanger are far less prone to having 'skew' away from the intended pivot axis, BUT, may be affected by Castor changes by simply changing bushing heights. Keep in mind, this isn't 'just' two-dimensional geometry, or 3-D Trig, but rather Also the Leverage changes, so TIME gets involved, which you FEEL as 'sluggish' or "quickness".
Funny how such a 'simple' device as a skateboard truck can suddenly be complex enough to require graphic calculators to pin down the exact happenings of just how much it's steering. If my Dad were still alive, he'd have it calc'd out in a few hours, but likely lose even my train-of-thought in the explanation. ;-)
And, Herbn, you're absolutely right, Bike's do relate. How else could you explain the yet-to-be-exceeded performance of the PVD truck?! Verdone worked from what he knows of Motorcycle Racing, and arguably made the finest (Arab's 'single action arguement notwithstanding) skateboard Racing truck ever. Yet, somehow, I get the feeling that YOUR homemade trucks (even those not like a Stroker) might yet define the cutting edge of lean-steer performance. The intuition of educated feet beats many CAD designs...
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re:Bike stuff
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On 12/7/2007 Brett Hunter Nelson
wrote in from
United States
(69.105.nnn.nnn)
That is true, the steeper the angle the quicker the turning. The arguement being made is in refrence to the effect of flipping a hanger with a positive or negative offset. If you look at the picture that HC posted it mentions a "fake pivot line". This could translate to bikes with offset wheels. The turning axis will still be the same, but the handling will certainly be different
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bike stuff
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On 12/5/2007 herbn
wrote in from
United States
(67.83.nnn.nnn)
how can it not be like bike stuff? there's got to be a relationship, could be inverse? could some aspects be similar and some inverse? doesn't a steeper geometry make for quicker turning in both devices?
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castor offset
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On 12/4/2007 hc
wrote in from
United States
(71.198.nnn.nnn)
the axle location affects leverage and load on the bushing, the trail stuff I am not so sure about, people have their own theories on it, but it ain't like bicycle stuff.
personally I don't like flipping the hanger, sluggish steering feel. btw, Magun's are built with negative offset
steveC's other diagram
http://i185.photobucket.com/albums/x193/SteveC8/R2Flip.jpg
I am not so sure how the bear trucks change steering angles, (or if it even does), haven't seen detail pics online.
btw, I am glad you used that pic from my site, I am happy when I see someone make use of it, it needs some updating though...
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Flipped Hangers
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On 12/4/2007
Brett Hunter Nelson
wrote in from
United States
(69.105.nnn.nnn)
Ha, too funny, didn't mean to bite your photo.
There was a diagram that I saw a while back that was actually a diagram of randal trucks one with a standard setup and one with a flipped hanger. I couldn't find it tho...
I understand what you are saying. Although, having tried it myself it seems to me that when they are flipped the turning was tuned down. Having thought about it, It seems that with a negative offset, the hanger would have less torque on the bushings, which may emulate a decreased geometry.
I suppose that despite the technicalities, weather it be the reduced height, negative offset, or modified geometry... the effect is a slightly more stable ride.
I had not put much thought into the question of weather the turning axis was between the hanger/baseplate pivot point and the bushing cup or weather it was between the hanger/baseplate pivot point and the axle... I think that with a precision truck it most certainly would be between the h/b p.p. and the bushing cup. But is it not possible that with a truck that has more play (randal/bear) at the bushing cup, it may be somewhere between the two? What do you think?
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steering axis
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On 12/4/2007
hc
wrote in from
United States
(71.198.nnn.nnn)
Brett, I understand what you are trying to say but its incorrect.
steering axis remains the same no matter where you put the axle.
it's same for bikes, cars, shopping carts, etc.
diagram by SteveC on SF
http://i185.photobucket.com/albums/x193/SteveC8/TruckDiagram2.jpg
red line is steering axis
btw that diagram is by chaput from my sk8sanjose data page.
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35's
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On 12/4/2007
munchh
wrote in from
United Kingdom
(86.145.nnn.nnn)
Yeah 35, but it didnt twig that my splits are 'not' cast, but billet.
Nightwork fries your brain!
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tracker
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On 12/4/2007 hc
wrote in from
United States
(71.198.nnn.nnn)
yea, it would cool if someone made a cast split randal-style truck.
might break in the middle though with split axle...
btw, downhill plates are 35 deg.
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offset
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On 12/4/2007 munchh@btinternet.com
wrote in from
United Kingdom
(86.145.nnn.nnn)
It will make a difference on an RII or UB copy, because the hanger is not a flat angle like the Randal down hill which is flat.
It is minimal, but at high speeds can make the difference in speed wobble and not, i used to use a downhill base plate (30 degrees) with the 180 RII hanger flipped on the back and the standard setup on the front, felt nice.
Just be carefull of being that little bit closer to wheel bite aswell!
Shame nobody has anything on the Tracker?
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Flipped Hangers
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On 12/4/2007
Brett Hunter Nelson
wrote in from
United States
(69.105.nnn.nnn)
Both Randals and Bear trucks come with a positive castor. Which means that the axle is slightly offset. If you were to draw a straight line from the point where the hanger and baseplate meet, through the pivot cup, the axle would be offset a few degrees (5 degrees with Bear trucks). This is why flipping them changes the geometry.
Bear 1052's and 852's come with a 52 degree baseplate. By default, the offset adds 5 degrees to get a geometry of 57 degrees. Flipping it subtracts 5 degrees to get 47.
This is a diagram of a truck with 0 offset/castor. Imagine the axle being placed just above the yellow line and you have RII's or Bear trucks. Flipping it would put it below the yellow line.
...Make sense?
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flip
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On 12/3/2007 hc
wrote in from
United States
(71.198.nnn.nnn)
flipping does not change steering angle.
(Bear trucks claims angle change by flipping, I don't see how that's possible)
flipping lowers it by about 5mm.
some riders don't like it flipped, some do.
go ahead and experiment.
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Randal Flipped Hangers
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On 12/3/2007
Brett Hunter Nelson
wrote in from
United States
(69.111.nnn.nnn)
Eh... "drop" your board... not quite. Randal hangers have a positive castor, or offset, so when you flip them it will lower your board by a few centimeters. The real difference will be that the geometry of the truck will be changed.
Randal R2's come with a 50 degree setup. By flipping the hangers you will change that to maybe 45 degrees or so. So the ride will be more stable, but turn slightly less. The dropping effect will be minimal but the geometry change might be what you are looking for.
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randal 180 hangar flipping
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On 12/3/2007
dh_turi_9
wrote in from
United States
(72.199.nnn.nnn)
i heard that if you flip the hangar on randals that it will drop your board. is that true? is that safe?
some one help me!
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Why so similar?
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On 11/28/2007
munchh
wrote in from
United Kingdom
(86.145.nnn.nnn)
Can i be devil's advocate for a minute and ask why after all this time, this truck is near as dam it the same as any of the other 50 degree, reverse kingpin, lets face it, Randal RII type trucks!?
They will be 180mm or 150mm, not a 100mm in site?
Nore the split axle on either side of the king pin that would have been a nice touch.
The only advantage with these is they will take a 'custom' bushing, which is nice as i've had my hole saw out lately.
I love Tracker and always will, but why just a touch above the others??
Please tell me if i'm missing something??
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terminology
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On 11/28/2007 hc
wrote in from
United States
(71.198.nnn.nnn)
got it Chris,
people been calling it the 'reverse kingpin design'.
I hate that name though.
I like 'perpendicular steering design'
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base plate - no angle - shux
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On 11/28/2007 Chris Yandall
wrote in from
United States
(66.91.nnn.nnn)
No I'm talking the base plate King Pin being angled as opposed to the upright kingpin design from the conventional trucks. My bad :)
Although Bennett does have the nice mounting plate hole design you mention....
cYa
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