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Linear vs. Progressive springs

redruM

redruM

Peripheral Visionary
Joined
May 31, 2011
Location
in a hologram, wrapped in a chimera and inserted i
Moto(s)
Turismo Veloce 800 / Dorsoduro 1200
I'm finally upgrading the stupid soft stock suspension on my bike. Yesterday, I ordered an Ohlins fully-adjustable shock and Race Tech fork springs (with both compression & rebound revalving kits). I went with the Race Tech [linear, 1.0 kg] largely because they were highly recommended by several people whose opinion I value... of course today, i'm browsing the net and come across riders who swear by progressive rate over linear springs for street use covering a wide variety of road conditions.

What drove me to hate my suspension in the first place is how the bike responds while riding aggressively (or not-so-aggressively) on bumpy/rutty/off-camber backroads. Jumpy, unstable, unplanted are the words that come to mind. Beyond that, I've been thrilled with the bikes handling and feel.

So now my question is - are linear Race Techs the way to go, or would I be happier with some progressive springs? I don't plan on tracking this bike.
 
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from what i've read, linear makes feeling what the suspension is doing more predictable and easier to adjust. harder to really dial it in for progressive springs?
 
With progressive springs the initial 75% of travel is soft, often causing excessive brake dive. It stiffens in the last 1" of fork travel which only serves to prevent bottoming. You don't want to blow through the initial travel so fast, this causes too much chassis movement leading to a very unsettled bike. Some bikes come with progressive fork springs stock but this is a less dramatic differential than what you'd get from Progressive Suspension. Linear rate springs are predictable and most riders don't want to delve into the mysteries of multi-rate spring/valving.
 
Well the front is typically linear but it depends on what people want. the rear on the other hand really depends on if it has a linkage and what that linkage does. Is it a rising rate? if so go linear. If no linkage go progressive.

With what you are saying I believe you made the right choice. I generally prefer linear on anything just cause I like things stiff and linear in general.
 
bunnygoat said:
With progressive springs the initial 75% of travel is soft, often causing excessive brake dive. It stiffens in the last 1" of fork travel which only serves to prevent bottoming. You don't want to blow through the initial travel so fast, this causes too much chassis movement leading to a very unsettled bike. Some bikes come with progressive fork springs stock but this is a less dramatic differential than what you'd get from Progressive Suspension. Linear rate springs are predictable and most riders don't want to delve into the mysteries of multi-rate spring/valving.
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I think your percent numbers are off a bit, and it will vary with the particular spring anyway. That aside, most suspension pros use only single rate springs and I tell folks to get the proper rate spring for their bike, body weight, load that you usually carry, and riding style. Then dial in the damping. (And in the case of the forks, also dial in the oil height.)
 
Both will work, if it's the right spring. The most important consideration is the willingness to change the spring if the weight is not right. The type of winding is a lot less important.
 
Generally speaking, progressive rate springs and linkages are better for varying loads and conditions(bumps).
Straight rate stuff(linear) is for a much more narrowly defined and spcific range of operation(racing). That is why virtually all street bikes-even the best high-performance sportbikes, come with progressive springs and linkage ratios. Your straight-rate stuff is better left to the track, even tho some top roadracers still use and sometimes prefer some progression-tho usually less than stock/street type rates. :party
 
Send Race Tech the forks, tell them what you weigh and how you ride, and it'll come back tits. They did my Ducati, and the thing I noticed most, is that I don't notice it doing anything bad.
 
corndog67 said:
Send Race Tech the forks, tell them what you weigh and how you ride, and it'll come back tits. They did my Ducati, and the thing I noticed most, is that I don't notice it doing anything bad.
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Having a good pro with experience go completely through your forks and adjust not only the spring, but preload, customize the damping, and set the oil level optimally (may be different from stock) can't be underestimated. Often dramatic and wonderful improvements can be immediately recognized. Even if it's just a street commuter bike. I highly recommend this approach.

But don't forget optimizing the rear suspension as well. It's best done in a complete package. And if you can get the work done locally, then you can easily have it all fine tuned as well.

Those who take this approach know of what I speak.
 
I switched from progressive springs to linear springs on my monster. If you are not varying conditions too much(i.e you only primarily ride street) I like the predictability of linear springs.

What I noticed with my old progressive springs is that when I set sag properly, I would sacrifice overall fork travel a bit. It just wouldn't use the full travel. When I set sag softer than usual, the bike would dive in more but I would get better use of the fork travel. I tried compensating with compression but the bike didn't feel right.

When I switched linear springs in my front forks. I was able to do both very well. Front end is rock solid over most bumps and extremely stable in turns. The only problem is that fixing the front has amplified the crappiness of my rear suspension. I would highly recommend that put some money aside to do either get the rear tuned by a pro or have the spring replaced to match your weight.
 
Linear
 
damping controls motion, springs support weight/force. using springs to control motion is silly since the force they apply is NOT dependent on suspension velocity, so needing springs that are stiffer as u go faster is also silly. IMO, using progressive springs is just a band-aid for improper damping.

jumpy & unstable on bumpy rutted roads points to a serious lack of high speed compression damping, which is pretty damn common w/ OE Honda valving. springs will do absolutely nothing to fix this... but those RaceTech valves could. hopefully they recommend a rly stiff compression stack from their chart for u, esp since their valve ports are HUGE.
 
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Linear is best IMO for the front and depends on the linkage for the rear, but like was said earlier, if the linkage has rising rate, go linear.

On my last ride I did Race Tech up front with valves and linear springs, and a dual rate (linear) set of shocks for the rear (Works). That's a really good option for cruisers and superior IMO to progressive rear in that case.

Good on you for getting into it and I am certain you'll improve your ride and learn a lot doing it.
 
The air in the fork is a progressive spring. If you have a progressive coil as well, the overall setup is going to be really, really progressive. That is, really mushy for most of the stroke and finally getting stiff when it's nearly bottomed out.

Valving can be an issue with progressive springs. Do you set the valving for the mushy part of the spring, and have it under damped when compressed? Or set it for the compressed part and have it over damped at normal ride height?

From what I've seen, the people that are recommending progressive springs are touring riders on Goldwings, Harleys, KLR's and such, and wouldn't know a proper suspension setup if it jumped up and slapped them.
 
SLOspeed said:
The air in the fork is a progressive spring.
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Good point. I forgot about that. And it's adjustable as well by varying the oil level, thus changing the volume of air being compressed.


SLOspeed said:
From what I've seen, the people that are recommending progressive springs are touring riders on Goldwings, Harleys, KLR's and such, and wouldn't know a proper suspension setup if it jumped up and slapped them.
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:laughing When Lindemann worked my forks over, he cut off the softer, progressive part of the spring and revalved and changed the weight of the oil and also changed the oil levels. The difference was astounding.
 
ST Guy said:
Good point. I forgot about that. And it's adjustable as well by varying the oil level, thus changing the volume of air being compressed.
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Aye...

I spoke with Jim at Catalyst about this. He too mentioned how the fork, even with the spring removed, is progressive by nature. He allayed my concerns once and for all; I bought the right hardware.

Thanks for the input all - can't wait to get it done :cool
 
There's always a need for air in any fork. Completely fill it with either metal hard bits or fluid and it wouldn't compress. Remember, the forks are sealed and since then extend and compress, the internal volume changes. Therefore some portion of whatever is inside the fork must be able to accomodate these volume changes. That means a gas. Usually air, but sometimes nitrogen or something else.
 
the only forks without an air spring would be ones that are not sealed. i think even Gas-Cartridge forks are sealed (AK-gas, Ohlins FGR, Penske Gas, etc) and have some measurable oil height.

of course, if the fork is empty of fluid and/or uve got a 200mm+ air gap, the air spring force is minimal even when bottomed out compared to the steel spring force. but its still there.
 
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