RE:aktiv New suspension design from Trek icw Penske Racing

[Iwan Kemp]

to bring the thread back on topic.. this is a good read on the Penske regressive damping setup....

 

Very interesting, yes. This quote comes to mind. "In theory there is no difference between practice and theory, but in practice there is."

 

Rider weight will have a massive effect on tune and overall feel and so too the speed at which it will be ridden. Team and factory riders are almost always good riders that can push a bike hard and are on the lighter side of life. A slower, heavier rider needs a different tune, but there's only a one-for-all available here. This is where Push and Tuned have the edge. Even Cane Creek as it has so many external settings available to tune your ride.

 

What is interesting though is Trek seeing the need to have OE Fox tuned before shipping it.

[Capricorn]

Very interesting, yes. This quote comes to mind. "In theory there is no difference between practice and theory, but in practice there is."

 

Rider weight will have a massive effect on tune and overall feel and so too the speed at which it will be ridden. Team and factory riders are almost always good riders that can push a bike hard and are on the lighter side of life. A slower, heavier rider needs a different tune, but there's only a one-for-all available here. This is where Push and Tuned have the edge. Even Cane Creek as it has so many external settings available to tune your ride.

 

What is interesting though is Trek seeing the need to have OE Fox tuned before shipping it.

 

very true, but the need for external adjustments, or some form of adjustment is true for any damper setup, and this is probably where Fox's expertise come in handy: knowing how to package the final product so as to make it end-user friendly 'enough'.

 

From reading that Penske document, it's clear that the blow-off can be adjusted by spring preload. That's an easy enough adjustment to offer. The curiosity will be in the remainder of the shock damping characteristic, and this again, is where Fox comes in. I'm beginning to feel more sure that Penske's involvement is limited to that blow off valve which is propietary and the concept of using regressive damping, while Fox's job is to package it into an existing shock design but with reworked internals to allow for regressive damping.

 

The regressive damping itself is still governed by pistons and shimstacks, which is pretty much still the standard these days. Push and Tuned will be doing much rubbing of hands.

[(Deon)]

edit: just remembered that they did say the shock has a switch for descending.

See, to me this is where the concept falls apart again. Unlike the SPV which I used unserviced for about 5 years on a Reign, there was no lever. It would climb, descend and take serious hits to flat during it's service. The only reason it was eventually replaced was due to a rock strike the took out the lower air valve. The RP23 replacement was always sub-standard in function... good but not the same.

 

Makes me think that all this tech is being developed because of suspension design failings. When a design relies on the shock to reduce bob, brake-jack, etc and still be expected to provide big hit damping with fine intricate circuits in the way, then it is flawed imo. Intricate valves and circuits are there to act as a patch for inefficiencies in design?

Edited June 13, 2014 by Pain or shine

[T-Bob]

Truthfully I watched the video a couple of times and just didn't really get it, it looked like a shock and acted like a shock. People went up and people went down. Then I got paranoid that the shock I've got just isn't good enough and I never noticed... FOMO.

 

I just need to know 4 things: does it work, is it any good, do I need a physics degree to set it up and can 'Droo service it.

[Capricorn]

See, to me this is where the concept falls apart again. Unlike the SPV which I used unserviced for about 5 years on a Reign, there was no lever. It would climb, descend and take serious hits to flat during it's service. The only reason it was eventually replaced was due to a rock strike the took out the lower air valve. The RP23 replacement was always sub-standard in function... good but not the same.

 

Makes me think that all this tech is being developed because of suspension design failings. When a design relies on the shock to reduce bob, brake-jack, etc and still be expected to provide big hit damping with fine intricate circuits in the way, then it is flawed imo. Intricate valves and circuits are there to act as a patch for inefficiencies in design?

 

there is always going to be a compromise, simply because shaft speeds are vastly different during climbs versus descents.

 

but I think i've misunderstood what the switch does. Based on the following image, it is now very clear what the CTD switch does: it simply changes the preload on the blow off valve. http://spokemagazine.com/files/2014/06/Trek_MTB_2014_MediaLaunch-21.jpg

 

 

This essentially addresses your concerns Pain or Shine. For DH, they'll leave out the CTD switch, and the shock will only perform according to the red curve. For enduro and trail riding, the blue curve will apply, and for all manner of climbing, the yellow curve.

 

i think its brilliant.

Edited June 13, 2014 by Capricorn

[GoLefty!!]

This is not new .Spez brain does the same ?

 

Brain is like a Curnutt threshold valve, similar to SPV and similar to Propedal.

They are all threshold valves that get activated by a system pressure spike.

 

Re:aktiv has nothing to do with the threshold, its a multistage compression damping circuit. NO current shock absorber fitted to a mountain bike uses this type of shock absorber in that all are currently single stage.

 

Not familiar with DVO yet but they could be doing something similar to Penske

Edited June 13, 2014 by GoLefty!!

[GoLefty!!]

See, to me this is where the concept falls apart again. Unlike the SPV which I used unserviced for about 5 years on a Reign, there was no lever. It would climb, descend and take serious hits to flat during it's service. The only reason it was eventually replaced was due to a rock strike the took out the lower air valve. The RP23 replacement was always sub-standard in function... good but not the same. Makes me think that all this tech is being developed because of suspension design failings. When a design relies on the shock to reduce bob, brake-jack, etc and still be expected to provide big hit damping with fine intricate circuits in the way, then it is flawed imo. Intricate valves and circuits are there to act as a patch for inefficiencies in design?

 

 

 

Re;Aktiv has nothing to do with CTD, SPV or propedal. Re; Akticv is not an add on to the compression circuit, it IS THE COMPRESSION CIRCUIT.

I think this is where everyone is confused because the marketing hype over the last few years has always focussed on the threshold valves that work ahead of the compression circuit.

 

CTD is a three different valving configurations that also relate to suspension travel. Its lever activated so the shock is only ever working on one circuit. Flip it and leave it.

 

As I posted above Re;Aktiv is a multistage compression circuit. Think of it as three SPV's on top of three compression circuits all tuned to activate at different shaft speed but tuned so that the response between each circuit is syncronous

[GoLefty!!]

And yet why not just go 150mm and have all that compatability from the DH wheeled side of things.

 

 

I suspect going 150mm will also have an effect on the rim manufacture not just the q-factor. To drill a rim for 150mm will require the spoke whole to be drill at an angle a few degrees closer to the axial plane of the hub. This could result in a strength loss.

Haven't done the calcs but the back of a cigarette box fudging seems to support the idea that flage width about 5-6 mm wider than current will increase wheel stiffness on a 29er wheel to closer to what a 26 offers.

 

glad to see the industry to acknowledging that 29er wheels are too stupidly weak through annually coming up with proprietry solutions to a simple problem of sticking a slightly smaller wheel

 

Argh well, no other way to extract money from addicts otherwise

[GoLefty!!]

Very interesting, yes. This quote comes to mind. "In theory there is no difference between practice and theory, but in practice there is." Rider weight will have a massive effect on tune and overall feel and so too the speed at which it will be ridden. Team and factory riders are almost always good riders that can push a bike hard and are on the lighter side of life. A slower, heavier rider needs a different tune, but there's only a one-for-all available here. This is where Push and Tuned have the edge. Even Cane Creek as it has so many external settings available to tune your ride. What is interesting though is Trek seeing the need to have OE Fox tuned before shipping it.

 

 

FOx have always tuned shocks to OE requirements before shipping. The RP23 in particular weretuned to specific requirements for bike size and estimated weight range. There was nothing stopping the end user form tuning it more to their liking.

What would be fantastic is if the retailer can adjust the tune of the suspension before delivering the shock to the customer.

I always retuned my Lefty to better suit my weight as I prefered a small frame but that came with shock tuning for a 64Kg rider and I was 10 kg heavier since I don;t have hollow bones.

 

For most riders, a Medium bike should have suspension tuned to a large weight range nstead of the assumption that every person who buys the bike is a pro rider spending 6 hrs a day on their machine.

[Johan Bornman]

Brain is like a Curnutt threshold valve, similar to SPV and similar to Propedal.

They are all threshold valves that get activated by a system pressure spike.

 

Re:aktiv has nothing to do with the threshold, its a multistage compression damping circuit. NO current shock absorber fitted to a mountain bike uses this type of shock absorber in that all are currently single stage.

 

Not familiar with DVO yet but they could be doing something similar to Penske

I agree that these are all threshold level valves but the difference lies in where the spike comes from.

The Brain's valve is located on the rear chainstay and picks up spikes from the ground up, i.e. bumps.

The others have the valve located on the shock and this pick up spikes from the rider down or ground up., it cannot distinguish.

I'll give you a bizarre example. Put a Brain bike stationary on the ground and have a rider jump onto the bike like Clint Eastwood does to his horse from the first floor of the saloon. Nothing will happen with the rear suspension and the bike will not soften his fall.

Do the same with a SPV bike and Clint lives to procreate.

I'm not assigning value to any of the methods.

Also the Brain's valve is an inertia valve and the SPV one not. In my limited experience of test-riding SPV and Brain shocks, I think the SPV blow-off is less sudden than the pop-release feel of a Brain.

But, all this is just a side-show to the interesting RE: Active discussion.

[Johan Bornman]

I suspect going 150mm will also have an effect on the rim manufacture not just the q-factor. To drill a rim for 150mm will require the spoke whole to be drill at an angle a few degrees closer to the axial plane of the hub. This could result in a strength loss.

Haven't done the calcs but the back of a cigarette box fudging seems to support the idea that flage width about 5-6 mm wider than current will increase wheel stiffness on a 29er wheel to closer to what a 26 offers.

 

glad to see the industry to acknowledging that 29er wheels are too stupidly weak through annually coming up with proprietry solutions to a simple problem of sticking a slightly smaller wheel

 

Argh well, no other way to extract money from addicts otherwise

I had a quick look in my hub measurement database to see how various manufacturers handle 150mm hub spacing and what they do with the "extra spacing"

Some use it to balance the spoke bracing angle on the left and right of the wheel, others squander it by maintaining unequal spoke tension.

Examples cited as hub flange distance from centre of hub:

Novatek: Left 42mm/Right 28mm

Ringle: 34/29

Hope: 26.5/26.5

DT: 25.8/25.8

 

The bracing angle for a given hub laced to a 29 and 26 inch wheel differs by less than 1 degree.

This means that we have to widen the hubs (110mm in front and approx. 150mm in the rear) and use the extra width to improve the bracing angle, in order to catch up with 26 inch wheel stiffness. In addition, we require four extra spokes in a 29er.

 

I think the 29er format has a long way to go before strength is optimum.

[rudi-h]

Re;Aktiv has nothing to do with CTD, SPV or propedal. Re; Akticv is not an add on to the compression circuit, it IS THE COMPRESSION CIRCUIT.

I think this is where everyone is confused because the marketing hype over the last few years has always focussed on the threshold valves that work ahead of the compression circuit.

 

CTD is a three different valving configurations that also relate to suspension travel. Its lever activated so the shock is only ever working on one circuit. Flip it and leave it.

 

As I posted above Re;Aktiv is a multistage compression circuit. Think of it as three SPV's on top of three compression circuits all tuned to activate at different shaft speed but tuned so that the response between each circuit is syncronous

 

Damn, you seem to know quite a bit about shocks. So if I understand you correctly this means that the Re:Aktiv concept is going to do away with on-shock adjustment settings such as CTD, propedal, etc.?

[Capricorn]

Damn, you seem to know quite a bit about shocks. So if I understand you correctly this means that the Re:Aktiv concept is going to do away with on-shock adjustment settings such as CTD, propedal, etc.?

 

look at what CTD switching does to the damping curves of the new shock a few posts above. it's simply a means to modify the damping characteristics tobe more application specific. CTD as a concept wont change, so it will stay.

Edited June 13, 2014 by Capricorn

[rudi-h]

look at what CTD switching does to the damping curves of the new shock. it's simply a means to modify the curve to more application specific. CTD as a concept wont change, so it will stay.

 

OK, so I am correct in summarizing that:

 

1) The Re:Aktiv is a seemingly very complicated mechanism that results in a steeper damping curve than any other shock on the market

 

2) It will still have three stiffness settings (CTD) that will be selected manually based on the type of riding that you are doing.

Edited June 13, 2014 by rudi-h

[Capricorn]

OK, so I am correct in summarizing that:

 

1) The Re:Aktiv is a seemingly very complicated mechanism that results in a steeper damping curve than any other shock on the market

 

2) It will still have three stiffness settings (CTD) that will be selected manually based on the type of riding that you are doing.

 

 

1) No. It's a different damping characteristic from what's been used before in bicycle suspension. The steep part of the curve is higher compression damping that occurs under low shaft speeds, like going around a bermed corner very fast, or when pedalling hard or during a speed climb You dont want the suspension to be too active much during those scenarios, so the steeper curve (higher damping force) is ideal.

Fast shaft speed would occur when hitting an object on the trail. Then the curve shows a decrease in damping force which improves bump absorption.

 

The mechanism to achieve this is actually alot simpler than what has gone before.

 

The CTD switch just changes the point in the curve where it drops off to handle bumps, and i suspect it does this by varying the preload on a spring that handles what is called blow off, the point in the curve that goes from steep to decreasing.

 

2) Yes.

 

 

what could be more complicated than the mechanism or damping circuit, is the concept of regressive damping. We've become accustomed to the standard damping circuits out there. This is a paradigm shift for MTB, so it's going to take a while for ppl to understand what this shift is, and more importantly, what it means to them when out riding. But at the end of the day, its best just to hop on and ride. If it feels good, who really cares how it works (me me me!!), as long as it does.

Edited June 13, 2014 by Capricorn

[(Deon)]

I get it now.. I think.