why doesnt anyone use dual rate springs in mtb

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6/26/2014 12:34 PM

springs with dual rates are used in cars and trucks but why not on our bikes?



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6/26/2014 2:03 PM

Because we use air shocks now

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6/26/2014 2:06 PM

Cars and trucks generally have a lot more limitations with packaging, and don't have the luxury to move the shock around to modify the leverage ratio curve (although they call it Motion Ratio or Installation Ratio in the automotive world) as much.
Even without a linkage driven system, you can move the shock around to get a progressive leverage curve on a mountain bike, which removes the need for a progressively wound spring. And, with a linkage driven system, you have additional ways to modify the leverage curve.

TL;DR: cars and trucks are very limited on leverage curves due to packaging, so progressively wound springs are sometimes used. Mountain bikes can be made with the leverage curves desired by moving the shock around or using a linkage.

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6/26/2014 2:11 PM

reseRved wrote:

Because we use air shocks now

Airshocks still suck on small bump stuff. the dual rate springs seem interesting because you should get really good small bump and still have ramp up. yeah some linkages achieve this (more or less, more like less most of the time), but what about forks? no linkages there. Why don't we have dual rate ti springs in boxxers and stuff.

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6/26/2014 2:14 PM

The Enginerd wrote:

Cars and trucks generally have a lot more limitations with packaging, and don't have the luxury to move the shock around to modify the leverage ratio curve (although they call it Motion Ratio or Installation Ratio in the automotive world) as much.
Even without a linkage driven system, you can move the shock around to get a progressive leverage curve on a mountain bike, which removes the need for a progressively wound spring. And, with a linkage driven system, you have additional ways to modify the leverage curve.

TL;DR: cars and trucks are very limited on leverage curves due to packaging, so progressively wound springs are sometimes used. Mountain bikes can be made with the leverage curves desired by moving the shock around or using a linkage.

that make sense. so why not have something simple light and reliable like an orange 224 and put a dual rate spring on it instead of come up with crazy linkages?

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6/26/2014 2:19 PM

The Enginerd wrote:

Cars and trucks generally have a lot more limitations with packaging, and don't have the luxury to move the shock around to modify the leverage ratio curve (although they call it Motion Ratio or Installation Ratio in the automotive world) as much.
Even without a linkage driven system, you can move the shock around to get a progressive leverage curve on a mountain bike, which removes the need for a progressively wound spring. And, with a linkage driven system, you have additional ways to modify the leverage curve.

TL;DR: cars and trucks are very limited on leverage curves due to packaging, so progressively wound springs are sometimes used. Mountain bikes can be made with the leverage curves desired by moving the shock around or using a linkage.

OCsponger587 wrote:

that make sense. so why not have something simple light and reliable like an orange 224 and put a dual rate spring on it instead of come up with crazy linkages?

That's the design philosophy that I used on the Guerrilla Gravity GG/DH, except I went one step further. No linkage, progressive leverage curve, standard coil shock.

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6/26/2014 2:21 PM

reseRved wrote:

Because we use air shocks now

scarface wrote:

Airshocks still suck on small bump stuff. the dual rate springs seem interesting because you should get really good small bump and still have ramp up. yeah some linkages achieve this (more or less, more like less most of the time), but what about forks? no linkages there. Why don't we have dual rate ti springs in boxxers and stuff.

That's a leverage curve issue. Air shocks have had an overall similar spring curve shape for a long time. The frame should be designed around it, if it's designed to use an air sprung shock. You can make a frame with good small bump compliance that uses off-the-shelf air shocks.

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6/26/2014 2:44 PM

reseRved wrote:

Because we use air shocks now

scarface wrote:

Airshocks still suck on small bump stuff. the dual rate springs seem interesting because you should get really good small bump and still have ramp up. yeah some linkages achieve this (more or less, more like less most of the time), but what about forks? no linkages there. Why don't we have dual rate ti springs in boxxers and stuff.

The Enginerd wrote:

That's a leverage curve issue. Air shocks have had an overall similar spring curve shape for a long time. The frame should be designed around it, if it's designed to use an air sprung shock. You can make a frame with good small bump compliance that uses off-the-shelf air shocks.

maybe. but even if you do, it lasts all about 5 rides then the airshock starts getting sticky and everything gets harsh again.

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6/26/2014 3:02 PM

scarface wrote:

Airshocks still suck on small bump stuff. the dual rate springs seem interesting because you should get really good small bump and still have ramp up. yeah some linkages achieve this (more or less, more like less most of the time), but what about forks? no linkages there. Why don't we have dual rate ti springs in boxxers and stuff.

On a coil sprung fork, yeah, it would make sense to have a progressively wound spring, which is common on motorcycles.
It seems MTB forks are gravitating towards air springs, even for DH, though. Then, air volume can be adjusted for the same effect, such as the Rockshox bottomless tokens, the Float 40 top air piston level and MRP's Ramp Control, etc.

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6/26/2014 3:32 PM

The Enginerd wrote:

Cars and trucks generally have a lot more limitations with packaging, and don't have the luxury to move the shock around to modify the leverage ratio curve (although they call it Motion Ratio or Installation Ratio in the automotive world) as much.
Even without a linkage driven system, you can move the shock around to get a progressive leverage curve on a mountain bike, which removes the need for a progressively wound spring. And, with a linkage driven system, you have additional ways to modify the leverage curve.

TL;DR: cars and trucks are very limited on leverage curves due to packaging, so progressively wound springs are sometimes used. Mountain bikes can be made with the leverage curves desired by moving the shock around or using a linkage.

OCsponger587 wrote:

that make sense. so why not have something simple light and reliable like an orange 224 and put a dual rate spring on it instead of come up with crazy linkages?

LOL you said Orange was light! that thing is a TANK

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6/26/2014 5:54 PM
Edited Date/Time: 6/26/2014 5:55 PM

For proper suspension performance, a damper system requires one correct spring rate for the specific body being supported through the entirety of its stroke. Higher damping or faster rebound at a certain shock position needs to be adjusted via compression or rebound controls. That is why there are forks with high and low speed compression / rebound damping for this purpose. (After market modifications like Avalange cartridges even offer medium speed tunes as well).

I you feel like you have a soft initial stroke and not enough support later in your travel this is a compression issue. Trust me, you have one correct spring weight, find it, run it. Correct spring rate is the first thing to set when tuning suspension. The rest of your damping is controlled by the compression unit. Rebound is then the last item to be set.

There are all kinds of videos out there by many brands on how to step through this process step by step. Look one up, it'll change how your bikes performs for the better.

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6/27/2014 2:42 AM

scarface wrote:

maybe. but even if you do, it lasts all about 5 rides then the airshock starts getting sticky and everything gets harsh again.

Use BOS.

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6/27/2014 4:14 AM

reseRved wrote:

Because we use air shocks now

scarface wrote:

Airshocks still suck on small bump stuff. the dual rate springs seem interesting because you should get really good small bump and still have ramp up. yeah some linkages achieve this (more or less, more like less most of the time), but what about forks? no linkages there. Why don't we have dual rate ti springs in boxxers and stuff.

according to 27.5 specific damping... you don't need much small bump sensitivity due to the larger wheel taking care of them... so air is fine.

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