DDC Suspension
- Thread starter Monners
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Surely the spring is made to a certain length for a reason, Alex is right, change the length and change the reaction, you're reducing the amount of travel therefore reducing the optimal area of use?
This is what I was thinking...you're reducing travel.
I'd be surprised if the spring is compressed anywhere near its maximum, when the forks are fully compressed. This is 100% just my thoughts from an engineering point of view, I have very little knowledge of suspension.
fast_ryan
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Springs
If you reduce spring length you are effectively reducing travel and increasing stiffness. You would probably need to to revalve the suspension as well to take into account the decrease in travel and change in stroke.
If you reduce spring length you are effectively reducing travel and increasing stiffness. You would probably need to to revalve the suspension as well to take into account the decrease in travel and change in stroke.
Agreed and I can't find any diagrams/cutaways on the interwebs, accurately depicting what happens, through the stroke of a normal spring.
scooby
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i thought non progressive spring rate was the same regardless of length,as in takes same amount of force to compress as coils are constant.this is a misconception with preload,it doesn't effect the spring rate just the ride height.so for the mupo to change actuall spring rate i'm assuming the springs are progressive,coils are tighter at the top?
So many people think you stiffen the spring by adjusting the preload. It doesnt work like that.
As for the mupo they could be a linier but if you make the top 2 coils rigid you make the spring shorter so its stiffer.
Im guessing the travel stays the same somehow.
Otherwise you couldnt set the preload correctly.
As for the mupo they could be a linier but if you make the top 2 coils rigid you make the spring shorter so its stiffer.
Im guessing the travel stays the same somehow.
Otherwise you couldnt set the preload correctly.
I asked Dave Moss...Not wholly sure if he's saying they would be progressive or not.
"Linear spring coils do not touch at full compression. [I checked that at fork bottom the spring still has gaps]
Progressive spring coils are designed to touch in a set sequence based on shape and wind. The concept is the shorter the spring is the stiffer it becomes. It would be interesting to check the spring length compared to Ohlins, GP Suspension and KTech to see if and by how much, the MUPO spring is longer? The picture shows the different spring rates so clearly the long setting is the .90 rate."
Re Preload: the mupo appears to wind down the red insert moving the spring holder up and down the tube. This will add preload relative to the spring and its set point.
Re linear springs changing rate: sounds wrong to me. If a 4" linear spring is rated at 10nm making an 8" length of the same wind should have the same properties but longer, no?
- Alex
"Linear spring coils do not touch at full compression. [I checked that at fork bottom the spring still has gaps]
Progressive spring coils are designed to touch in a set sequence based on shape and wind. The concept is the shorter the spring is the stiffer it becomes. It would be interesting to check the spring length compared to Ohlins, GP Suspension and KTech to see if and by how much, the MUPO spring is longer? The picture shows the different spring rates so clearly the long setting is the .90 rate."
Re Preload: the mupo appears to wind down the red insert moving the spring holder up and down the tube. This will add preload relative to the spring and its set point.
Re linear springs changing rate: sounds wrong to me. If a 4" linear spring is rated at 10nm making an 8" length of the same wind should have the same properties but longer, no?
- Alex
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Interesting thread.
Progressive springs have been frowned upon for a while now as the logic is that the resistance increases exponentially until the limit is reached, which makes fine tuning and feel very difficult to gauge at the bottom of the stroke.
Progressive springs have been frowned upon for a while now as the logic is that the resistance increases exponentially until the limit is reached, which makes fine tuning and feel very difficult to gauge at the bottom of the stroke.
They are linier. Found an early video showing how they work.
https://youtu.be/tfGJjDiK5n0
https://youtu.be/tfGJjDiK5n0
Thanks for the information/links.
Monners
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I got in touch with Dave Croft from Mupo earlier to discuss this stuff and ended up buying their top shelf CSP30 forks and factory rear shock for the race bike. Didn't even bring up the 911 oops!! I'll get some answers when I speak to him next.
Nice, expect it to work very nicely.
Would be cool to understand the 911 system as I expect there are advantages for amateurs as well as professionals.
- Alex
Just found this, makes it sound infinitely variable.
"The construction of the spring coil itself is generally what determines a spring rate ? whether it?s thicker metal to increase stiffness, or thinner to decrease stiffness, even the distance between each wind and the number of active coils determines the rate.
Mupo?s patent-pending K911 fork cartridges simply control the number of active coils by disengaging anywhere from zero to a handful at the top of the spring. The higher the number of coils the cartridge disengages, the higher the spring rate? and conversely, the less coils the cartridge disengages, the lower the spring rate.
This innovation might not seem like a massive improvement on the surface, but imagine you?ve had to make last-minute setup decisions, as most of us have had to at some point."
http://www.ukclubsport.com/mupo-suspension-changing-game-part-two/
- Alex
"The construction of the spring coil itself is generally what determines a spring rate ? whether it?s thicker metal to increase stiffness, or thinner to decrease stiffness, even the distance between each wind and the number of active coils determines the rate.
Mupo?s patent-pending K911 fork cartridges simply control the number of active coils by disengaging anywhere from zero to a handful at the top of the spring. The higher the number of coils the cartridge disengages, the higher the spring rate? and conversely, the less coils the cartridge disengages, the lower the spring rate.
This innovation might not seem like a massive improvement on the surface, but imagine you?ve had to make last-minute setup decisions, as most of us have had to at some point."
http://www.ukclubsport.com/mupo-suspension-changing-game-part-two/
- Alex
If I were a regular track day rider I would be interested in having this setup, really interesting read Alex. Do you fancy changing to Mupo?
Me? No, but I have full Ohlins already. Nix30 + TTX GP. Came off of Ben's (Felix's) bike. And I only did that because the price was right.
I am just curious when people do something different. Snake Oil vs Genuine Article. I want to understand the trade-off, it might be entirely acceptable, but I do want to quantify it so others can make informed choices.
- Alex
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