Hello all.

I did a thread not long ago about how I totally upgraded the suspension of my Iron 883 all around with Progressive 412s in the rear and their matching springs in the front.

Well, while I was initially pleased with the setup, over the last week or two, I have developed a number of gripes about how the front springs are performing, and I've decided to take them off and install a set of RaceTech springs at a rate of .90kg/mm.

I feel like in order to explain this, I should quickly touch on what it means to be a "progressive" spring (not to be confused with Progressive Suspension, the company) versus a "straight rate" spring.

A straight rate spring will have the same resistance, the same "rate" throughout its compression. It does actually change just a little, but not nearly as much as the progressive spring. The downside here is that the rate MUST be chosen properly for the weight of the bike + rider combination, so straight rate springs are kind of "custom" for each bike+rider.

A progressive spring will change its rate based on how much it has been compressed. It may be very soft when it has not been compressed yet, possibly .6kg/mm...and then as you compress it down, it increases its rate (rate is essentially the force the spring pushes back with) and becomes stiffer (possibly as high as 1.2-1.4kg/mm if my info is correct). It is an attempt at a "one size fits all" spring that will be soft enough to soak up little bumps and small potholes, but still fix brake dive and other big compression issues that the stock springs really don't handle well.

The theory at play with a progressive spring is that if you hit a big bump or brake really hard, the spring will compress through the soft part and hit the harder rate section of the spring, where it will provide the increased stiffness to handle the jolt.

This is a great theory, but I personally feel that the rate that Progressive Suspension has chosen for the spring they are offering for the Iron 883 is simply wrong. The soft part is TOO soft. The hard part is TOO hard.

First: Too much sag, regardless of preload. I have now experimented with spacers that use zero preload, .5" of preload, 1" of preload, and 1.25" of preload. Regardless of how much preload I give the shock, the static sag (the amount of compression of the fork under the weight of the bike alone) is almost 50% of the total travel!

Static sag should typically be NOT more than 1/3 of the total compression of the fork...but the progressive front springs sag too much, no matter how you set the preload.

The result of this, is that the weight of the bike causes the fork to sag through the soft, nice part of the shock that is designed to soak up bumps...and you end up riding around on a VERY hard, VERY unforgiving front spring setup.

YES, its true that the bike corners like a sportbike on SMOOTH roads...but if you encounter a bump or elevation change mid corner, a setup this hard will imbalance the bike too much and in my opinion is not ideal for the street.

Now that I have hundreds of miles on the progressive springs, I am sure that they are simply not right for me and this bike. Maybe for a rider who is 125-150lbs they would be great, but I weigh 195 without gear and 205 with gear...and the result in my case has been that the progressive front spring IS an improvement over stock in terms of cornering ability, but NOT at all in terms of rider comfort or the ability to stay composed on uneven road surfaces.

If I was setting my 883 up for a trackday, the progressive spring would actually probably work great, but for real world riding in the twisties, where the roads aren't perfect and potholes/bumps/cracks/etc...are a reality, these springs are just not right.

I've called RaceTech this morning (used their springs in race bikes long ago with great success) and talked with a tech there who basically said that he hears this same complaint a lot from harley guys. After discussing my weight, and intended riding style, we settled on an ideal rate of .90kg/mm for my bike and my order is being shipped out today.

I'll post a DIY thread with pics of the spring swap later on, but I just wanted to share this experience with the forum.

My overall opinion now is that the Progressive Suspension 400 series rear shocks are still absolutely amazing and worth every penny, but the front springs really don't work for a 200lb rider unless you don't mind dodging every single bump and pothole that the road will throw at you. These front springs are KILLING my lower back.

I'll update this with pics of the swap an an initial ride report as soon as the RaceTech springs arrive.

Meanwhile, if anyone wants to try these springs on their bike, once they are off the bike, I'll gladly sell them for $25 + shipping. I think for a much lighter rider, they would work well, but if you are 175+lbs...these probably aren't what you want.

The only downside is that the racetech springs are $125, almost exactly twice the cost of the Progressives.

 

What weight fork oil are you using. I have Progressive Fork Springs in my 2007 1200 C and they have about 15,000 miles on them. I have no such issues and I weigh 200 lbs. I run 7w BelRay Fork oil in them. They follow the contour of whatever surface I'm on very well.

 

I'm running the factory HD oil which is only 2 years old and is supposedly 7w if the info I read online is correct.

I almost wonder if I got the wrong part number or something, because these Progressive springs are just not right. Nothing is binding, the fork oil level is essentially exactly where it was on the factory spring...but damn these springs are sagging too much AND way too harsh...its like the worst of both worlds.

 

I put progressives on my boys 883 low. It ended up with essentially zero static sag and right at 1/3 sag with his 210 pound butt on it. I dont think oil weight or level have anything to do with sag. Probably too late but have you looked into Works? (I think thats the name of them) With them you can set the cross over point from soft spring to harder spring exactly where you want it.

 

I went with RaceTech fork springs (.80kg/mm), Ricor Intiminators and 5wt Amsoil.

Fantastic ride.

 

I would tend to believe this may be the case. My progressives sag 1" when I mount the bike.
Fork oil weight shouldn't be affecting your sage situation, it affects the damping rate.

 

Straight rate springs rock and you will love them. Makes the front much more predictable. I put RaceTech springs in everything I can.

 

Yeah, the more I think about this, the more it sounds like I may have been sent the wrong springs?

I'm not bashing Progessive at all. If there was an error, it may not have been theirs. I ordered it through Powersport Superstore via Amazon.

At any rate, I'll be looking forward to comparing the Racetech springs to the Progressives to see how they do.

 

I have single-rate springs in both my Sporty and Glide. A good mod, helped greatly by setting sag correct, which raises ride height a little and gives more fork travel to ride on.

 

UPDATE: Got the RaceTech 90kg front springs installed today and WOW, what a difference!

By my measurements, I hit just about 25% static sag (25% of total travel) and 35% total sag with me on the bike in my gear.

This was with .6" of preload on the RaceTech 90kg springs.

My rider weight is 205 with gear.

Test ride: Definitely a lot better than the Progressive springs. The sag is now correct, the springs really allow the front to move under those hard bumps, but they are firm enough that you get a very planted, solid feel in the corners and when braking. The dive in the front under hard braking is about .75", leaving about another .75" or so of total travel to work with.

These springs correct all of the problems I was having with the progressive springs, and I could not be happier.

I still think Progressive makes a great product, I LOVE the 412s I have on this bike in the rear.

All I can think is either the set I got was for a different bike, it was out of spec, or it was just NOT suited to this bike + my rider weight.

This is the suspension I always wanted (in terms of springs), now the only step up from this is a set of Gold Valve emulators and that is for another day.

I just went out and blasted over the best and worst roads in the area, and the bike is perfect this way. It soaks up the bumps on the highway, it is very very tolerable on terrible roads, but once you get on it and lean the bike over into a corner, it stays very composed.

I even went out and took a very nasty sweeper near me, that has a terrible kink in the pavement. The first time I hit that bump in the road while leaned over, I almost wrecked (this was on the stock suspension). I hit this thing at about 60, hung off the bike and the bike just ate up the bump with VERY little overall disturbance to the weight distribution on the tires.

Another way I can tell these springs are perfect: If I'm stopped on level ground, and I put my feet down and take the weight off of the bike, and then drop straight down onto the seat with all my weight, it sags evenly in the front and rear, and it now rebounds evenly in the front and the rear also.

With the progressive front springs, the rear would drop way more than the front and you could feel that the front and rear of the bike were not balanced well.

This is perfect, I would recommend this combination to anyone for a 200lb rider on an Iron:

13" 412s in the rear
RaceTech 90kg springs in the front with .6" of preload and the factory oil at the factory oil height.