As the subject line says, I'd like to learn about stable platform technology in suspension system. I've done a bit of googling, and I think I have the basic concept: the suspension is stiff at low frequencies, but compliant at high frequencies. Feel free to correct me if I'm wrong.
I'd like to learn a little more... How do you achieve this goal? Is there a suspension primer that describes the techniques that different companies use? I've heard of Fox's inertial damper, Rock Shox' motion control, etc., but I'd like to see an explanation of how they work. Maybe I need to look at motorcycle suspensions?
As the subject line says, I'd like to learn about stable platform technology in suspension system. I've done a bit of googling, and I think I have the basic concept: the suspension is stiff at low frequencies, but compliant at high frequencies. Feel free to correct me if I'm wrong.
I'd like to learn a little more... How do you achieve this goal? Is there a suspension primer that describes the techniques that different companies use? I've heard of Fox's inertial damper, Rock Shox' motion control, etc., but I'd like to see an explanation of how they work. Maybe I need to look at motorcycle suspensions?
"dvt" <[email hidden]> wrote in message news:[email hidden]...
Quoted message said:
As the subject line says, I'd like to learn about stable platform technology in suspension system. I've done a bit of googling, and I think I have the basic concept: the suspension is stiff at low frequencies, but compliant at high frequencies. Feel free to correct me if I'm wrong.
I'd like to learn a little more... How do you achieve this goal? Is there a suspension primer that describes the techniques that different companies use? I've heard of Fox's inertial damper, Rock Shox' motion control, etc., but I'd like to see an explanation of how they work. Maybe I need to look at motorcycle suspensions?
Thanks for any help you can offer.
-- Dave dvt at psu dot edu
It is hard to separate the fact from the hype in the bike industry. Stable platform shocks are suppose to not react on forces from above (the rider), like pedal induced bob and brake dive. And still soak up the bumps in the trail. Some complain that they do loose some small bump compliance. I have not bought a new shock in two years so I have no first hand knowledge.
"dvt" <[email hidden]> wrote in message news:[email hidden]...
Quoted message said:
As the subject line says, I'd like to learn about stable platform technology in suspension system. I've done a bit of googling, and I think I have the basic concept: the suspension is stiff at low frequencies, but compliant at high frequencies. Feel free to correct me if I'm wrong.
I'd like to learn a little more... How do you achieve this goal? Is there a suspension primer that describes the techniques that different companies use? I've heard of Fox's inertial damper, Rock Shox' motion control, etc., but I'd like to see an explanation of how they work. Maybe I need to look at motorcycle suspensions?
Thanks for any help you can offer.
-- Dave dvt at psu dot edu
It is hard to separate the fact from the hype in the bike industry. Stable platform shocks are suppose to not react on forces from above (the rider), like pedal induced bob and brake dive. And still soak up the bumps in the trail. Some complain that they do loose some small bump compliance. I have not bought a new shock in two years so I have no first hand knowledge.
As the subject line says, I'd like to learn about stable platform technology in suspension system. I've done a bit of googling, and I think I have the basic concept: the suspension is stiff at low frequencies, but compliant at high frequencies. Feel free to correct me if I'm wrong.
I'd like to learn a little more... How do you achieve this goal? Is there a suspension primer that describes the techniques that different companies use? I've heard of Fox's inertial damper, Rock Shox' motion control, etc., but I'd like to see an explanation of how they work. Maybe I need to look at motorcycle suspensions?
There are automotive texts from as far back as at least the 1930s that deal with this adequately from the standpoint of hydraulic shock absorber design, but you'll very hard-pressed to find them in most libraries. There are hints in some of the tech bulletins from various sources within the automotive industry, but once again, good luck finding them. It's primarily a matter of valving issues; the valve opening pressures and sizes need to be closely matched to the load and the motion ranges expected for the unit. From what I have seen so far, it does not appear that the majority of bike shocks incorporate any such features to any meaningful extent. -- Typoes are a feature, not a bug. Some gardening required to reply via email. Words processed in a facility that contains nuts.
The patent referenced on that page is also interesting; go to www.uspto.gov, click search/patent number search, and enter the patent number (6,581,948) to view it.
In the Fox system, the damping seems to be adjusted, not the spring rate. And it appears that the damping is changed depending on whether the wheel moves up (i.e. a bump) or the fork crown is pushed down (i.e. pedal forces).
In the Fox system, the damping seems to be adjusted, not the spring rate. And it appears that the damping is changed depending on whether the wheel moves up (i.e. a bump) or the fork crown is pushed down (i.e. pedal forces).
And how does the shock know if the vertical motion is coming from a bump on the ground or from pedaling force or the rider shifting his/her weight forward?
Does this mean you can't bunny hop on a bike with a "stable platform" shock?
I think it distinguishes based on the speed. Basically the purpose of these systems is to prevent pedal bob. The compression that occurs with each pedal is much slower than the compression from hitting a bump.
The Fox system is an inertia valve, related to but different from stable platform valving.
In the Fox system, the damping seems to be adjusted, not the spring rate. And it appears that the damping is changed depending on whether the wheel moves up (i.e. a bump) or the fork crown is pushed down (i.e. pedal forces).
Quoted message said:
And how does the shock know if the vertical motion is coming from a bump on the ground or from pedaling force or the rider shifting his/her weight forward?
The link explains it with a picture. My text is a feeble attempt to summarize their explanation. A bump on the ground makes the wheel move up initially, while the pedaling force or weight shifting on flat ground starts with a downward push from the top. Of course there is a rebound in the opposite direction...
Quoted message said:
Does this mean you can't bunny hop on a bike with a "stable platform" shock?
Looks to me like it would be *easier* to bunny hop a bike with a stable platform compared to an otherwise similar bike. But I haven't tried it.
I think it distinguishes based on the speed. Basically the purpose of these systems is to prevent pedal bob. The compression that occurs with each pedal is much slower than the compression from hitting a bump.
The Fox system is an inertia valve, related to but different from stable platform valving.
You're right, the Fox system is not primarily based on the speed of the impact. If stable platform *is* based on the impact rate, how do they do that?
I just found some references to Curnutt, and I'm perusing his patents... I think I may learn something there.
I think it distinguishes based on the speed. Basically the purpose of these systems is to prevent pedal bob. The compression that occurs with each pedal is much slower than the compression from hitting a bump.
The Fox system is an inertia valve, related to but different from stable platform valving.
Yes, it is. It is an on-off switch, not a continuously operational system. It goes nearly rigid at one point, and then fully active, and then rigid again. -- Phil, Squid-in-Training
