[chillindrdude]

http://www.vitalmtb.com/features/Formula-1-Meets-Mountain-Biking-in-Treks-New-RE-activ-Suspension,732

Seems like a great marketing job, at least to me. The Re:Aktiv damper sounds like it IS an inertial damper; relying on mass to move in order to open low resistance oil flow path to create that digressive curve.

it appears to really only work on a very progressive suspension leverage curve, no? wouldn't that digressive damper create a wallowy feeling least when you want it hitting a square edge bump at speed? i guess it's counterintuitive, but I want progressive support as i am going through the travel and increasing shaft speeds, not some weird drop off before the damping force catches me.

or am I not reading the hype correctly?

discuss.

 

[Da Peach]

I'm not Penske material.

 

[tacubaya]

 

[tacubaya]

Looks like a fancy propedal.

 

[chillindrdude]

my guess if it actually worked better than propedal, fox would either steal it, and/or refuse to bring it to market. seems gimmicky.

 

[HardtailHack]

So, like an Avy Mid Valve kit for your shock?

"This kit consists of MidValve shims stacked in front of the rebound check plate.
This allows the check plate to limit the flow on very low speed fork movements by reducing the gap or "Float"
that the check plate can open, and as the speed increases the amount the MidValve shims bend open will
prevent fork dive from heavy braking, jump faces or rolling bumps.
Because the check plate is stacked with shims, at higher fork speeds the MidValve
and check plate will open completely allowing the MidValve to flow more oil without any harshness.
This MidValve can be tailored to your type of riding by changing the shim configuration to increase the gap or "Float"
and or change the stiffness of the stack to determine at what speed the MidValve transitions to a check valve.

 

[dcamp29]

Hey guys-

I was the lead (Trek) engineer on this shock. I've already answered a bunch of questions on Vital, but feel free to ask any RM style questions here I guess...


To stop any speculating:

-It is not a mass damper. It has a Penske style regressive valve inside it.
-The licensing goes something like this: Trek has exclusive rights to Penske technologies, Fox is the manufacturer. I'm guessing this will be a Trek exclusive tech similar to DRCV.
-It doesn't feel wallowy on our bikes. Those graphs from Vital are marketing illustrations... take them with a grain of salt.
-It works pretty good.
-It has many shims(z) in it.

 

[kidwoo]

But how many shimz? Specifically.......


And is it enough?

 

[dcamp29]

But how many shimz? Specifically.......


And is it enough?

my first design replaced all the oil with shims, but it felt a little harsh.


It has enough+1 shims. specifically.

 

[mykel]

http://shop.penskeshocks.com/files/downloads/ETM 12.1 REG-A.pdf

for un automabooble, but a bit more detail on the thee-rie.

 

[tacubaya]

Penske's regressive valve installed on rebound side.

Holy mother of hysteresis.

 

[kidwoo]

It has enough+1 shims. specifically.

Well that's just good science.

Well done!

 

[Kanye West]

So, high-speed only bypass valve?

 

[FarkinRyan]

What is a penske-style regressive valve?

Is it 'pretty good' in the way a CTD fork is 'pretty good'?

 

[norbar]

Why not just go with a suspension design that doesn't bob unless you pedal so bad you loose your health insurance every time you try to do it.

 

[scottishmark]

OMGz! Trek is in danger of winning at teh Monkey!

First ever manufacturer to have the correct number of shimz?!?!

 

[dcamp29]

What is a penske-style regressive valve?

Is it 'pretty good' in the way a CTD fork is 'pretty good'?

It's like the regressive valve that Penske makes for car applications.

If I said it was 'the best shock evarrrr!!!' RM would rip me to shreds. I think it is a solid improvement over current CTD DRCV rear shocks.

 

[dcamp29]

So, high-speed only bypass valve?

no- the regressive valve does low-speed control, then when oil passes through it, there is a secondary shim stack that helps with high speed.

Why not just go with a suspension design that doesn't bob unless you pedal so bad you loose your health insurance every time you try to do it.

that is a good suggestion.

 

[dcamp29]

OMGz! Trek is in danger of winning at teh Monkey!

First ever manufacturer to have the correct number of shimz?!?!

It's only because I was on RM before employed by Trek. I learned everything here.

 

[HardtailHack]

It's only because I was on RM before employed by Trek. I learned everything here.

Helping prove that all forum members are engineers, nice!

Going back a bunch of years, isn't this just a better version of the Reactor Valve that Romic had?

 

[scottishmark]

It's only because I was on RM before employed by Trek. I learned everything here.

So it will come in Rootbeer AND fit a 3 inch Gazzalodi?? Sweet.

 

[dcamp29]

Helping prove that all forum members are engineers, nice!

Going back a bunch of years, isn't this just a better version of the Reactor Valve that Romic had?

Lol yeah- all RM members are really smart.




do you have a drawing or something? I don't remember anything about this "reactor valve"? This thing is pretty unique on the inside.

 

[CBJ]

I'm not Penske material.

Glad I'm not the only one who had this as the first thought.

 

[blindboxx2334]

ctd is still ctd to me.

i cant wait until i get back from vacation and track down a CC inline to put on my fuel ex. f 'proprietary' sizing and ctd.

 

[Vrock]

To me it looks like something between a platform and a standar LSC-HSC Damper, you can have a bit more LSC than with a standar shock without compromising HSC, but it's not as hard as a platform, so it's going to work nice on trail bikes. On XC Bikes Platform it's still what most people want and on AM-Enduro Bikes it's better to have a lot of tunning options (CCDB) unless you can build a better shock with that valve, then it's game on...

Can you buid a nicer shock with that valve? Fox Float X with HSC adjustment on the piggy for example. And also, are you going to use standar size shocks on the new models or are you going to keep using odd sizes?

 

[dcamp29]

you can have a bit more LSC than with a standar shock without compromising HSC, but it's not as hard as a platform, so it's going to work nice on trail bikes.

Very true- I think this shock is best for trail bikes with the current tune

Can you buid a nicer shock with that valve? Fox Float X with HSC adjustment on the piggy for example. And also, are you going to use standar size shocks on the new models or are you going to keep using odd sizes?

Still odd shock sizes. I'm trying to convince the frame guys to go back to standard sizes...eventually it should happen, but these are being built into existing size DRCV shocks, so odd mounting and odd lengths.

I think the valve would fit in a float x, but I doubt Fox will sell you teh parts to do it. Maybe eventually?

 

[Vrock]

One more question... How does the new Monarch Debonair compares to the Fox DRCV? It's "the same concept" build into a standar shock, so I like it better unless you tell me that DRCV has a much better spring curve.

 

[tacubaya]

No, DRCV is a secondary positive chamber that "activates" when you reach a certain point in travel, DebonAir is just an air sleeve with increased negative and positive air chamber volume to slightly reduce the air spring "hammock" and to reduce the air spring force gradient in the beginning of travel.

 

[Vrock]

It's the same idea, getting a better spring curve out of an air shock.

 

[dcamp29]

You guys are both right. DRCV was implemented to reduce the hammock looking spring curve of air shocks. Debonair does the same thing with a much larger volume negative spring. Both work well. The debonair curve is almost identical to DRCV with the push spacers (which I use). I think it's great- less money and less potential problems vs DRCV shocks and very similar feel.

 

[tacubaya]

It's the same idea, getting a better spring curve out of an air shock.

Yep I agree with that.. I'm just saying those two systems had different specific targets in mind, one was to affect the beginning force gradient where was the other was to affect the second and third thirds of travel.

 

[Vrock]

When you use a huge negative air chamber it changes the whole spring curve, not just the beggining.

 

[tacubaya]

When you use a huge negative air chamber it changes the whole spring curve, not just the beggining.

I never said the contrary

 

[blindboxx2334]

So, before i let this thread die.

has anyone used the push volume spacer kit for the non-penske drcv shocks? ive got the smaller spacer in mine currently. although i couldnt get the bigger one to work.

 

[dcamp29]

I use/designed those spacers... what was wrong with the larger spacer?

 

[blindboxx2334]

oh nice! well. the smaller one feels great.. better bottoming resistance. although the shock still bottoms far too easily for my liking.

so, then i tried installing the bigger spacer. it pretty much made the shock locked out the whole time.. even after i took a fair amount of pressure out.

the shock isnt too bad, i would just prefer it to be higher up in the travel.

 

[dcamp29]

oh nice! well. the smaller one feels great.. better bottoming resistance. although the shock still bottoms far too easily for my liking.

so, then i tried installing the bigger spacer. it pretty much made the shock locked out the whole time.. even after i took a fair amount of pressure out.

the shock isnt too bad, i would just prefer it to be higher up in the travel.

ah. ok- I thought the spacer didn't fit or something...

You can always drill/cut some material off the large spacer to get somewhere in-between the small and large. Unfortunately the spacers really only effect spring curve after DRCV rod is engaged (roughly 50% travel) so getting the bike to ride higher will mean small spacer + more pressure.

 

[stim]

dcamp29, I have a question, not about the new Penske damper but about the DRCV system...

Is there only one valve to fill both chambers of the shock? If so, this means at zero travel the chambers are at equal pressure right?

 

[dcamp29]

Yes- the fill valve goes to both chambers, so right when you pump up the shock, the two chambers are at equal pressure. But- as soon as you compress the shock to DRCV activation point (50% travel) the upper chamber equalizes with lower chamber through the rod-valve. Then when you let the shock extend, the rod-valve seals at 50% travel, and the upper chamber ends up staying at a higher pressure.

Say you fill to 200 psi. Once you bounce on the bike, the lower chamber is probably at around 100psi and the upper is at around 300psi. When the bike is compressed to 50% travel and beyond, the pressures are equalized through the DRCV valve.

 

[stim]

Ok, thought so thanks. So the challenge is to match the spring rate gradients for before and after the valve opens so as not to feel the change.