ST1100 with Progressive 465 Rear Shock

[paulcb]

I recently bought and just installed a lightly used Progressive 465 shock on my '01 ST1100 ABSII with 98k miles. The OEM shock 'seemed' to be OK... it didn't pogo, but sometimes bottomed out with pre-load set in the middle.

I'm not sure what to set the sag at. Right now, with a little static compression of the spring by the threaded ring when completely unloaded, the sag is set to about 2". For reference, if the spring is not compressed by the ring at all, the sag is about 3". What should the sag be on my bike with that shock? Note that the rear, i.e. seat, is now a bit lower, maybe 1/2".

Apologies if I'm not clear, but I'm no suspension expert, at all. Feel free to press me on more detail if necessary. TIA.

 

[Larry Fine]

You do realize that the only thing you're really adjusting is the ride height for a given total weight, right?

In other words, a given spring will compress to a given length with a given total weight load, period.

I have the same shock/spring on my '01 ST1100, and adjust for best handling. not static ride height.

The higher the rear, the quicker the steering response and ease of turning; too far causes instability.

 

[TerryS]

This is how I ran my 465. That was based on getting just about 8mm of static sag (bike only) and worked well with my 90kg on board.

 

[The Cheese]

At 98k miles it is overdue for a rebuild. By like 70k miles! Get it rebuilt and then go from there. Whoever rebuilds it will be able to tell you how to set it up for you.

 

[paulcb]

At 98k miles it is overdue for a rebuild. By like 70k miles! Get it rebuilt and then go from there. Whoever rebuilds it will be able to tell you how to set it up for you.

The 465 shock is like new, very few miles, so it's good. My original shock has 98k on it. Sorry if I wasn't clear in my OP.

 

[paulcb]

Thanks for the input Larry and Terry. My 465 spring is not nearly as compressed as yours Terry, maybe 1/3 as much, which I think is not enough for my weight (82kg). I think I need to adjust it, as the bike sits too low right now. Interestingly, I took a high speed cloverleaf yesterday that I often ride on, which has a few bumps/waves in the middle of it's turn. I was a little surprised to find the back end noticeably more stable than before, even with my current "less than optimal" settings.

 

[TerryS]

If your old shock was loosing it's rebound damping, you will have had a loose and bouncy ride no matter where the spring preload was adjusted. As stated above, the spring preload is controlling the ride height and hence the bottoming resistance. A general rule of thumb is that you want to have 1/4 to 1/3 of the travel used up when you are sitting on the bike. And then set the rebound damping to allow the fastest rate of rebound while still maintaining control i.e. no pogoing.

 

[paulcb]

Thanks Terry. What I don't know is how much actual travel I have, thus I'm not sure what 1/4 to 1/3 of that would be. I'll work on measuring that based upon the shock dims.

 

[ReSTored]

This is the 465 shock I put on my 1100. https://www.progressivesuspension.com/product/1426/465-series-shock

Here is the spec (page 24) including travel. https://www.progressivesuspension.com/assets/files/7100-105-Specs-And-Tech-Info.pdf

YT video of 465 install.

I set my sag at 1.25"

There is a caution in the install instructions to never set the spring shorter than 6.87" or shock damage could occur.

 

[sirbike]

Thanks for the input Larry and Terry. My 465 spring is not nearly as compressed as yours Terry, maybe 1/3 as much, which I think is not enough for my weight (82kg). I think I need to adjust it, as the bike sits too low right now. Interestingly, I took a high speed cloverleaf yesterday that I often ride on, which has a few bumps/waves in the middle of it's turn. I was a little surprised to find the back end noticeably more stable than before, even with my current "less than optimal" settings.

Sweet, glad to see it is on track for improving your ride.

 

[SMSW]

You do realize that the only thing you're really adjusting is the ride height for a given total weight, right?

In other words, a given spring will compress to a given length with a given total weight load, period.

There is a bit more to it than that. Assume for a moment that the spring's rating is 150 lbs per inch, i.e. a load of that weight will compress it 1". Further, assume the bike is weightless (or if you prefer, add whatever number for the back end of the bike and subtract it later). With the spring/shock on the bike, and a weightless bike, it will sit at a given attitude. Add 1" of preload and the rear will rise up that inch since the bike is weightless. A rider weighing 150# gets on and the bike's rear will not drop at all because the spring is under compression and will require 151 or more pounds to compress further. This of course assumes all of the riders weight is on the rear shock - not true but we can assume that for the sake of argument. Now if our rider cranks in say 3" of preload, the bike will need to see a rider + passenger weighing 450 lbs before the rear shock spring will begin to collapse any farther. Our 150 lb rider alone with this 3" of preload has effectively converted his bike to a hardtail and he will feel every bump and ripple in the pavement. If he goes fast enough and the step input of a bump exceeds the 300# of preload then yes, the shock will function as designed.

So, while the preload does set ride attitude, too much for a given load will also affect the suspension and feel of the bike over bumps. In the real world, we probably cannot dial in 3 times the rider's weight in preload, so to a certain extent this explanation is moot.

 

[Larry Fine]

A rider weighing 150# gets on and the bike's rear will not drop at all because the spring is under compression and will require 151 or more pounds to compress further.

Now if our rider cranks in say 3" of preload, the bike will need to see a rider + passenger weighing 450 lbs before the rear shock spring will begin to collapse any farther.

Our 150 lb rider alone with this 3" of preload has effectively converted his bike to a hardtail and he will feel every bump and ripple in the pavement. If he goes fast enough and the step input of a bump exceeds the 300# of preload then yes, the shock will function as designed.

So, while the preload does set ride attitude, too much for a given load will also affect the suspension and feel of the bike over bumps.

I disagree with these statements.

 

[Rob20111]

I also just purchased a lightly used 465 and am waiting for it to arrive.
As far as setup goes, the rear wheel travel on an ST1100 is 120mm (4.7 inches)
Progressive recommends setting at 1/3 travel or 40mm.(1.57 inches)
Since the shock is stock length these numbers should suffice.
They also recommend setting rebound at position 3 as a starting point.
These of course are only recommendations, and your needs may require further adjustment.

I used this formula to setup the Progressive 450 IAS shock on my GL1500 Wing and have been quite pleased with the results.

 

[Larry Fine]

Let me expand (no pun intended): with a given weight, a given spring will compress to a given length (unless something physically, inhibits motion, such as topping or bottoming against stops.)

Adding a given amount of load will compress the spring to a new, shorter length; likewise, removing a given amount of load will allow the spring to expand to a new, longer length.

Again, with no outside physical resistance or restraints, where along the shock body you set the adjustable end of the spring in no way whatsoever changes the above statements.

If you raise the rings 1/2", the top of the spring, and thus the shock, will rise 1/2", unless you add weight to compensate; of course, we actually adjust the rings to compensate for added weight.

None of this affects the dampening of motion as the road undulates beneath the bike, only the position of the (for example) 3"of movement along the suspension's 7" capability of travel.

The only exception would be if you had a shock absorber (which only dampens motion, and supports no weight) that had a shaft that changed damping with position, but I've never heard of one.

If the ideal at-rest fully-loaded height of a random point of the rear of the bike is at (again, making up a number) 32" from the ground, we adjust the spring so it's at that height as presently loaded.

Every time we pick up or drop off a passenger, or even add or remove groceries, we should be adjusting the suspension. Or, the headlight should be at the same height without having to adjust it.

 

[paulcb]

Thanks for the video, Progressive links and input. I adjusted it again last night to 1.5" of sag. I'm leaning toward going to 1.25" but I'll leave it at 1.5" for a while and see how it goes. FWIW, today I went over that same cloverleaf I mentioned earlier just to test the new shock, and while it was much better than stock at my first setting (~2"), it's even better now at 1.5".

Thanks again for everyone's input.