Fork Spring Upgrade Question

[Guest nasadiver]

Just throwing it out there. I know the stiock is linear, but it just seems like going progressive would give so much more in the way of performance. I commute about 40 miles each way whenever the weather allows, and I like hitting the twisties whenever time allows. Fairly aggressive, but not too extreme.

So,.....linear or progressive?

I probably already know the answer, just trying to understand the concepts behind it a little better,......especially as explained by people with experience between the two on the VFR.

Thanks.

[Guest]

I know the stiock is linear

As opposed to the "stock". :goofy:

[vfrjim2002]

Just throwing it out there. I know the stiock is linear, but it just seems like going progressive would give so much more in the way of performance. I commute about 40 miles each way whenever the weather allows, and I like hitting the twisties whenever time allows. Fairly aggressive, but not too extreme.

So,.....linear or progressive?

I probably already know the answer, just trying to understand the concepts behind it a little better,......especially as explained by people with experience between the two on the VFR.

Thanks.

Actually the stock springs are progressive, some folks think much too progressive. Slammer has a thread around here somewhere that goes into exquisite detail measuring the effective spring rates at various degrees of compression. Personally, I just got around to installing a set of linear (.95kg/mm) racetech springs in the evil vtec. Can't offer any evaluation yet as I haven't gotten her fork legs bolted back in.

Edit: Here ya go: http://www.vfrdiscussion.com/forum/index.php?showtopic=28721

[Veefer800Canuck]

The argument against progressive springs is that the damping rate is the same throughout the fork travel, from full extension to full compression.

Since the job of damping is to control the motion of the spring, it is therefore impossible to get the damping set perfectly for the entire stroke with progressive springs.

If you set it up for proper control of the lighter part of the spring, the heavier part of the spring will be underdamped.

If you set it up for proper control of the heavier part of the spring, the lighter part of the spring will be overdamped.

Best bet is to get a set of straight-rate springs that are correct for your weight and riding style, then set the damping for that spring rate.

IIRC, Miguel mentioned that Race-Tech's spring and damping recommendations are biased toward the "track" side of the equation, so you should be honest with them (or whomever is doing your forks) about your riding, whether it be commuting or touring so you can spec a setup that is at more home on the mean streets, and not just the back straight.

I think Miguel also mentioned going a little lighter on the shim stack than RT recommends, simply for ride quality on less than perfect pavement.

[Guest]

I would choose linear. The travel on a street bike compare to an offroad bike is too short to fullly take advantage of the progressive rate. My $.02

[supraman66]

What happens when you bring rising rate springs into the equation??

Just thougtht I would stir the pot a little more

[skuuter]

(IMO).....I think they need to "tight-wind" a longer distance of the progressive spring they give us(since we're gonna be given a progressive spring-don't personally like em'), so damping / dampening doesn't take such an abrupt change so soon.....would be better except for the real aggressive riders, who probably would be better off with linear springs anyway.....my 2 cents........... :thumbsup:

[fallzboater]

What happens when you bring rising rate springs into the equation??

Just thougtht I would stir the pot a little more

Progressive-wound springs are rising-rate.

Standard slider forks are linear, but rear suspension geometry can be designed to be rising-rate, linear, or falling-rate. In reality, the rate will change somewhat through the suspension travel.

Progressive springs are good for accomodating a wide range of rider weights while providing compliance and bottoming resistance, so it makes sense on stock bikes. IMO, linear is better for setting up the suspension for a specific rider.

[skuuter]

What happens when you bring rising rate springs into the equation??

Just thougtht I would stir the pot a little more

Progressive-wound springs are rising-rate.

Standard slider forks are linear, but rear suspension geometry can be designed to be rising-rate, linear, or falling-rate. In reality, the rate will change somewhat through the suspension travel.

Progressive springs are good for accomodating a wide range of rider weights while providing compliance and bottoming resistance, so it makes sense on stock bikes. IMO, linear is better for setting up the suspension for a specific rider.

Totally agree....and even though I've never been a fan of progressive springs, I also think they probably do a better job for ME overall because of my laid-back touring type of riding. Still would like to see a better-design set of em' in my forks. The fast, aggressive riders on here(IMO), would be better off finding some linear springs in a poundage to their liking. If I did track days (won't be, except in a car), I would definetly be playing with linear rate springs................................. :thumbsup:

[Trace]

IIRC, Miguel mentioned that Race-Tech's spring and damping recommendations are biased toward the "track" side of the equation, so you should be honest with them (or whomever is doing your forks) about your riding, whether it be commuting or touring so you can spec a setup that is at more home on the mean streets, and not just the back straight.

I think Miguel also mentioned going a little lighter on the shim stack than RT recommends, simply for ride quality on less than perfect pavement.

I agree. I went with the .9 springs instead of the typical .95 or 1.00 that most 180-200 lb guys use, because with suspensions, "more" is not necessarily better. After all....it's a suspension, and it's supposed to suspend you and the bike to let the tires do their work, not jar your teeth. A compliant suspension is a working suspension, within limits, of course.

As for the compression valve shim stack selection, again I went one step "softer" than the recommendation....because all their recommendations are for racing setups, as in Race-Tech. However, the rebound stack is dependent on the spring used, so you can follow that recommendation. But since I went with F3 fork internals when I did this upgrade last spring, I have rebound adjustability and now that I'm learning and making sense of it all a little bit, that is a very nice feature to have. Of course, adjustable comp settings would be even better.... :goofy:

[skuuter]

Compression/ rebound adjustment capability was nice on my CBRs.....could dial em' in to suit my style (or lack of) of riding. Make a few notes, and could quickly adjust for loaded bag trips, by your self mountain twisty rides, with the wife rides, to work commuting, etc. At 165 lbs rebound adjustment is nice....................... :thumbsup:

[supraman66]

What happens when you bring rising rate springs into the equation??

Just thougtht I would stir the pot a little more

Progressive-wound springs are rising-rate.

Standard slider forks are linear, but rear suspension geometry can be designed to be rising-rate, linear, or falling-rate. In reality, the rate will change somewhat through the suspension travel.

Progressive springs are good for accomodating a wide range of rider weights while providing compliance and bottoming resistance, so it makes sense on stock bikes. IMO, linear is better for setting up the suspension for a specific rider.

Actually a progressive spring is a change to a higher rate not a continually increasing rate between two know variables.

Progressive rates change between two variables (7.5 on the short coils then quickly up to 9.5 on the longer coils (in essence two rates). Rising rates would start at 7.5 and increase exponentially to the maxumum of 9.5 (infinite number of rates).

Hyperpro sells rising rate springs and explains the difference quite well. I'm not sure of real world benefits, but then again I'm just stiring the pot.

[fallzboater]

Actually a progressive spring is a change to a higher rate not a continually increasing rate between two know variables.

That's Hyperpro's marketing jargon, but I agree that a well-designed progressive-rate spring would not have an immediate transition between two greatly differing rates. I think if you measured most other progressive springs you wouldn't see a sharp inflection point like on Hyperpro's conceptual graph. They may sell the best progressive springs (and call them rising rate); all I know is that most suspension tuners will perscribe linear springs of an appropriate rate for the application.

Hyperpro

Here's another thing that bothers me about Hyperpro. If you look up your bike, they will recommend one spring part number. It doesn't matter if you're a 100 lb solo rider, or 350 lb two-up plus luggage. Just like OEM, they're expecting the progressive windings to handle everthing, just by varying the amount of preload. Not going to work. Hyperpro may do a better job than Honda (fork springs too soft for almost everybody) at selecting appropriate rates, but they're still only going to be optimal for a relatively small range of weights.

[supraman66]

Actually a progressive spring is a change to a higher rate not a continually increasing rate between two know variables.

Here's another thing that bothers me about Hyperpro. If you look up your bike, they will recommend one spring part number. It doesn't matter if you're a 100 lb solo rider, or 350 lb two-up plus luggage. Just like OEM, they're expecting the progressive windings to handle everthing, just by varying the amount of preload. Not going to work. Hyperpro may do a better job than Honda (fork springs too soft for almost everybody) at selecting appropriate rates, but they're still only going to be optimal for a relatively small range of weights.

It's funny you said that because that is the exact question I sent to hyperpro. Seems like they would have to have different initial and ending rates for different sized loads in order to get the correct sag.

Great minds think alike! :thumbsup:

[fallzboater]

It's funny you said that because that is the exact question I sent to hyperpro. Seems like they would have to have different initial and ending rates for different sized loads in order to get the correct sag.

Let us know what their reply is, if you get one. You can almost always get the correct sag by varying preload (may require different spacers), but you can still have less than optimal rates.

It'd also be interesting to know what their spring rate range is.

[Guest]

What happens when you bring rising rate springs into the equation??

Just thougtht I would stir the pot a little more

I think that is what I may be referring to as "Progressive". As I've always understood it, as by definition, linear is the same rate throughout,.....dual-rate, or two-step, is a spring that has two distinct sections of differently spaced coils, the transition can be abrupt when the spring compresses to the point where the windings change rate.........whereas a true "progressive" spring is a spring that progressively gets stiffer the more it is compressed. The coils are ALL spaced different. The gap between each coil incrementally gets smaller towards the stiffer end. That way, over the little stuff the spring reacts very quickly and subtly, whereas when the hits become harsher and compress the spring further down the "progression" the rate increases correspondingly.

The HyperPro website has a great pictoral showing the difference and describing the performance differences.

http://www.hyperprousa.com/catalog.php?cat=Springs

So I guess, according to even their terminology, I should have used the term "rising rate", rather than progressive.

My bad.

Same question, different wording,........Linear or Rising Rate?