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Added a comment about feature Formula 1 Meets Mountain Biking in Trek's New RE:aktiv Suspension 6/14/2014 8:23 PM
JMSharp814

matman, your assumption on one thing is correct. I currently do reside in North Carolina where I am working with a Nascar organization so I am well aware of building regressive shocks using just a piston and shim combination. I will attest that I am not a believer in the method in Nascar. While I know Penske preaches teams are using it here, I would argue it is very rarely on a car and even less prominent, if ever has reached victory lane in Nascar.
I am assuming you work with Penske shocks and have been drinking the Kool-Aid of regressive dampers solving the racing worlds problems that they have been serving the past 3-5 years. Without going into a long drawn out explanation of my background and what I have done with shocks, I am well aware of the other regressive methods out there. When I was doing IndyCar dampers before I came to Nascar we used a 4 way adjustable ohlins that had a piston that would create a regressive curve on curb hits. I am well aware the stuff we are using in Nascar is very limited to what is out there in other forms of motorsports. I still will argue that it isn't as popular as Penske claims it to be. I know regressive shocks have won races, but week in and week out I would venture to say in all forms of racing from drag cars to snowmobiles, regressive dampers are in the minority and wins for it are few and far between. Yes, it has won, but you and I both know even junk can find victory lane.
This has gotten off topic a bit so I will try to reign it back in. I am not a fan of regressive shocks in general, that is no surprise. I still stand by my original post that it is something that is unpredictable and no matter how generic you have made it, a generic tune can not be most effective for every rider and every condition,with something like this. I also will argue it is a gimmick because in terms of force, the amount of regression is minimal at best from the graphs that have been posted. A digressive build with bleed would yield very similar results, but then Penske wouldn't be needed to develop that or be able to make money off a patented valve.
My offer still stands to you or Dave, or anyone else involved with this project, I'll gladly demo one and give a full report after spending some time on a dyno with the shock. It's easy to say it works and EVERYONE loves it in a cool video and article than to show actual dyno graphs and real numbers. The balls in your court to make me a believer.. If what you are proclaiming is legit, you'll have no problems sending one my way. I'll be waiting, but not holding my breath, if you get my drift.

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Added a comment about feature Formula 1 Meets Mountain Biking in Trek's New RE:aktiv Suspension 6/13/2014 6:30 PM
JMSharp814

Dave, definitely no concerns here. I am confident that what I am saying is a legit argument. I agree there are a million variables with shocks in general but I definitely feel from my experience with regressive technology that to put a generic tune on something like this is doing very little justice for the general public. While I understand EVERYONE who has tried it has liked it, the exact technology you are comparing this shock build to is anything but "generic". Your marketing campaign directly compares to the build as technology used in F1 and IndyCar but those builds are anything but generic tunes designed specifically with thousands of dollars of testing for a certain velocity hit at the perfect moment.

I am not discounting the fact you may have hit on something by putting a steep nose on a compression build that effectively blows off on bigger hits. This technology is nothing new with off-road dampers. While most off-road applications use a very linear build, blow offs (basically a digressive) have been around for decades and offer a suitable alternative to the linear shock in certain circumstances. I honestly would like to ride one of these Treks with this shock but more importantly I would like to spend some time with a dyno and this shock to really get a true reading on the actual regression and consistency of it at different speeds and pressures. I'll supply the dyno and man hours, will you (Trek) supply the bike and the shock?

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Added a comment about feature Formula 1 Meets Mountain Biking in Trek's New RE:aktiv Suspension 6/12/2014 7:49 PM
JMSharp814

Penske racing has been pushing regressive technology for several years now. They have had some success with it in F1 and in IndyCar, but an F1 car and an IndyCar are quite different from a mountain bike. Mainly in the amount of travel and the velocities seen on track. Traveling 3-5 mm and working within a small velocity window makes this technology a lot easier to tune. Plus add in the countless hours and money spent on specific rig and track testing along with data collection and equipment used to get this perfect regression at the perfect moment and you have created quite the nightmare for your average rider. Having some experience working with this technology, I am going to play devils advocate here and point out some issues I see with the technology and how it is being marketed here. First and foremost is the repeatability of the regression and the speeds at which the regressive part of the damper kicks in. There is no way a person weighing 120 lbs and a person weighing 220 lbs creates the same shock velocity for a given action. This would imply that each shock needs to be specifically tuned to regress at the perfect velocity for each riders weight and riding condition. Second, the graphs show a minimal amount of actual regression. On a 15 inch per second test, how much regression in force is actually seen? The video eludes to riders commenting on the tire staying in contact with the ground better, but if the regressive part of the shock is on the compression part of the damper, how is that keeping the tire in better contact. Rebound is what keeps the tire in contact with the trail, not your compression. Compression soaks up the impact but rebound is what lets the shock allow the tire to stay in contact with the ground. How does regressive compression improve tire contact? I could go on and on and back and forth. While I am all for progression, this one is adding a lot of variables to the mix. I can tell you there has been a lot of money and data collection involved in getting regressive technology to work and it doesn't work in every occasion. It is not the cure all. I feel like it can work and it could be effective in certain instances with the right tuning for the right rider on the right trail, but as a blanket build for all riders and rider abilities on all the different terrain, that isn't realistic. I say the actual amount of regression is small and we are more talking marketing gimmick here than actual functionality, because to do this technology right each rider would need a shock dyno and a data system to maximize the regression at the velocity needed for their riding style and terrain choice. Basically the shock built is a digressive with a lot of bleed and a steep nose. A dyno will show some regression, but I would be interested in testing one to see exactly how much regression actually takes place in force at a given velocity. I am certain I could build something with a shim or orfice shock that was very similar without using a regressive valve and still achieve the same feel.

And to throw it out there because another poster brought it up, off-road and motocross are not using this technology for the very reasons I pointed out above. The sweet spot for the regression is too small and hard to predict with the repeatability issues. One time it will regress at 3ips and the next hit will be 4-5ips. Very unpredictable and not consistent. Plus the time to dial it in to a certain track is very hard in off-road due to changing track conditions and amount of data needed to be collected to get it close.

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