The Tuesday Tune Ep 14 - Busting Myths

[@theohlinsguy4649]

Great video in a KZbin sea or mis-information. My favorite is a so called professional shock that has what they call a "Velocity Dependent Piston". Pretty much every piston (at least the ones I work with) are velocity dependent unless I am missing something in the translation.

[@infidelmat]

Probably clumsy marketing speak for a multi-stage progressive shim stack instead of a simple stack or basic orifice damper. Or that there are high and low speed damping adjustment "channels". Damping is intrinsically velocity dependent in its most basic form so it must be one of those IMO.

[@gernotkvas6364]

Another great episode of the series. Keep it going!

[@alexandergavrilov5491]

Hi, how do I calculate the speed of a spring? Should its stiffness be divided by its compression stroke or should the mass that presses on the spring be divided by the compression stroke?

[@fireblade1986]

well if you'd really like to mess damping up one could play with fluid dynamics if you'd design a lowspeed circuit that has laminar flow at low shaft speeds, the effective flow rate can be higher at a given force ... just the flip-point into turbulant flow would typicly mean a really harsch transition in Damping force.... unless you create really fancy difusors on your ports ... but there we likely get into metal 3D printing

[@infidelmat]

Ti vs steel spring: coil springs aren't truly fully linear due to the way coil geometry works, but it's pretty close for all intensive purposes (smaller the displacement range the more linear they appear). But Ti springs require less coils per inch (so big spacing) due to lower material stiffness, and so this non linear coiling effect may become more apparent (in theory, I don't know if it's reasonable to say one could feel it). Also the way they are coiled due to the large spacing transitioning to the tighter spaced coil ends may introduce a progressive wind into the mix, but again I don't know if this could be noticeable.

[@testtesttesttesttest884]

Intents and purposes

[@alexandergavrilov5491]

How to calculate the damping speed?

[@leonardmag]

real position sensitive damper should be on the market from dt Swiss fork and ext shocks. Ext solution should be basically is basically just the piston entering a smaller tube at the end of the travel.

[@piciu256]

So like Manitou TPC+ or HBO in the newer forks?

[@spuddo123]

If the piston entered a smaller tube at the end of the travel then it would mean no overlap with the piston head and the inside of the shock body in the initial part of the stroke, therefore it could flex and get stuck on the smaller tube causing it to stop or even break, unless I'm missing something

[@piciu256]

@@spuddo123 it doesn't, Manitou just has a slightly floating cup at the end of the piston, chamfered at the end of course, I assume EX and everyone else with similar systems, does it the same way.

[@syammimarifin3437]

Is there any frequency dependant damping in mtb application, similar to Koni fsd system?

[@VorsprungSuspension]

Not precisely in the same manner, but Manitou's TPC+ has many similarities in that regard.

[@otaviogoncalves6383]

Hi! What diference make if you change the pressure on the ifp?

[@spuddo123]

Less risk of cavitation, but can affect the springrate. Ideally IFP pressures should be as low as possible without a risk of cavitating

[@sandy_knight]

LOL, "Semantically incorrect", aka marketing mumbo-jumbo... ;-)

[@MrTeilzeit]

So how does the progressive/degressive damping of the new Stumpjumper work? Or is it actually “not existing”? The ID imof the fox shock also claims being not linear in rebound 🤷🏼‍♂️

[@florihupf]

Thanks!!!

[@pukki34]

May I ask ; how its possible that the red line is lower on 50% sag than the linear line? it should be going always above the linear line. If you make the air space smaller (with bottomless tokens) the air pressure increases much faster when you compress the shock or fork.

[@VorsprungSuspension]

Basically if you were to run a hyper progressive setup at a much lower pressure then that's the curve you'd get. It's grossly exaggerated compared to anything you'd run in reality just so that it's easy to visualise on a graph.

[@DottorRox]

number 1 !!

[@tobiasdonner6268]

I have a very little nerdy thing to mention about the statement that spring force is the only factor that defines rebound speed: I am riding a DVO diamond fork (new fork is on the way and I'm planning on a coil kit), I'm riding the rebound relatively fast (rider weight ca 95kg, rebound setting is fully open). I notice a loud metallic "klonk" sound when I exit a berm and go directly in a manual to pump over a roller (lifting the handlebar quite fast out of the compression from the berm). I think the extension speed of the fork is at that moment higher than what only the spring can do because the inertia of the front wheel and lower leg creates an additional resistance against which I can pull to extend the fork even faster.

[@spuddo123]

Thats a very good point, not sure by what amount it would increase rebound speeds but it would definitely have some effect

[@piciu256]

The clunk you hear is just from the steel negative spring, typical thing with DVO forks.