When they are talking about clicks, its from all the way clockwise, then back for the number of clicks? In that case, Gwin Holy sh**
if you are 40+lbs lighter than me, a 450# spring is a bit much IMO....but then again, DW makes points as to why a super fast rider might use a heavier spring.
If you plan to run lots of compression damping (esp. LSC), you can get away with 50 lbs less spring rate on a CCDB. If you don't like to run a lot of compression damping, then go with the 450 lbs.
im actually liking the new tires that wear off a lot faster than previous years...the cars are still faster despite thisNot enjoying the Pirelli P Zero are we?
From the article:
Strain gauges on the cranks and h-bar, calibrated to give vertical (or maybe normal to nominal ground-plane) force (=m.a) of the rider, plus an accelerometer on the frame somewhere (but not while pedaling)?
Hah, mine goes to 11.
FFTs were taken of data logged whilst riding, not from a dyno... no point running frequency analysis on something where you're controlling the input frequency!
Jesus Christ!...I had no Idea what the hell I was walking into on this one.
Cool. What were the data channels? Wheel travel/t only or accels on frame as well?
Got it.Google "sex machines"
Crap. Replace "dyno" with "potentiometer" in my post. Brain fart moment...
Right, I think we are making points on totally different aspects of the ride here; my argument being mainly concerned with bike stability (particularly when cornering or slower compressions closer to the natural frequency of the bike) and you being more concerned with the high frequency response of the wheel than the chassis stability.
They were all on completely different frames, and all on custom valved shocks to boot. Comparing clicks tells you absolutely nothing; for all we know, it might have given them all exactly the same characteristics when measured at the wheel!
On the post shaker I built, suspension movement and input displacement, so I could compare how the suspension reacted to the input at different frequencies, and see how the rider interacted with the bike. Pretty sure nobody's actually undertaken this research before outside vehicle crash testing, I couldn't find ANY mention of it anywhere - the closest thing was some US Army papers I found on proportions of bodily mass (ie relative weights of your head, neck, torso, abdomen, hands, forearms, upper arms etc). Sadly the project was somewhat limited by financial and time constraints (the original aim was pretty ambitious!) but it taught me a LOT. On the bike it's just wheel position against time. Accelerometers would be cool though, I'm sure DW's got dozens of those little buggers floating around!
haha righto. FFTs of wheel displacement only give you very implicit data, as in you can't look at a PSD of wheel travel and go "well then I need more rebound and less HSC" or whatever. What it does is help you understand the natural frequencies of the bike itself (natural frequency of the wheel, natural frequency of the sprung mass, how the rider moves, pedalling inputs etc) much moreso than the relatively random inputs. If you rode down a set of stairs or on a course with unbelievable amounts of braking bumps (Thredbo for example) you might start to see discernable input frequencies, but for the most part nothing much shows up there, all it really does is show you the vehicle's modes of response. It's not easy stuff to understand, and I'm still learning a lot about it. However, relatively speaking, I'm only at the beginning of my research
"xSensor" app on iphone + gaffer tape = win!
hahah. Doesn't it only do up to 1 or 2 g's though?
+/1 1.3g I think. Sample rate might be too low as well (among other issues, though uses the gyro in v4 phones which is cool, so = 6 axis)...
You are more or less correct, for most bike dampers. The LS circuit is usually a small hole through the centre of the piston/shaft, that is partly blocked by a tapered needle that you wind in or out to close off/open up the size of the hole. The HS circuit is the large ports on the piston that are closed off by the shim stack, which may or may not be preloaded. If there's no (or very minimal) preload on the shim stack, the shim stack will affect the LS damping as well to some degree, because it will begin to open very slightly as soon as oil is moving at all. When you crank the HS adjuster, it increases the spring preload on the shim stack, keeping it closed for longer, and increasing the HS damping force somewhat as well.
My head hurts from reading this thread, but good info is being shared.
Changing the shim stack changes the 'knee' on the damping graph, or the threshold between the LSC and HSC. The shape of the curve below the knee is 100% LSC and is not changed by modifications to the shim stack. Adjusting the needle valve is the only way to change the shape of the LSC curve:
The following graph shows the change in overall damper curve via changes to the first shims in the shim stack. You can see, that the curve below the inflection point (knee) is always the same shape...what does change however is the point where the shims open, and the regressive HSC takes over
To stay in the LSC region 'longer' you need to make the shim stack such that it takes more force to open. Stiffer or more large shims next to the piston face are one way to do this.
The further away from the piston face....you are effecting the regression of the HSC curve. If the tapper in shims is agressive (fat short pyramid) the curve will be more regressive. If the shim stack tapers less, the HSC curve will be less regressive in nature.
Images as well as some very good reading from here: http://www.peterverdonedesigns.com/damping.htm
Probably not as high as you'd expect, mostly (but definitely not entirely) below about 5Hz. High frequency stuff is relatively random, and the super high frequency stuff (like say above 15Hz) has virtually no impact on the suspension, it just gets sucked up by the tyres. Consider that you can actually hear vibrations from about 20Hz upwards though though...
I hope you guys get a chance to talk to Luis Arraiz (K9) one day...this is just the kind of analysis he does to set up CCDBs for riders. Captures the data on board, looks at the frequency analysis, then uses what he knows from the dyno curves of the shock to tune out the proper frequencies, both for low speed and high speed. And from what I know, it's pretty effective.
I actually met him briefly at Ft Bill in 2007 purely by chance. Cool that he's making a concerted effort to be methodical and by all accounts generally doing a good job, but there are a few theories of his that I disagree with (though by the same token I'm sure there are a few people who think I'm full of **** too!). He is doing some cool stuff (whether effective or not) of considering the little details of bike performance though, like those fork spring bearings.
Agreed. I'd love to see more hard data supporting suspension setup choices (and design) before jumping back into the full-suspension +/- big bike fray in the future.
