setting sag?

[rodantking]

I installed new springs and spacers, but when I checked sag I am at 50mm. In my head, if I want 35mm adding 15mm will be to much. By the way this is a staight spring rate, but don't they still get progessive as they compress?

Any input would be sweet.

[Redbird]

In my head, if I want 35mm adding 15mm will be to much.

You're correct. Spacer is preload, sag is sag, two different things. Preload obviously effects sag, but it's not a direct relationship. I'd guess that you need to add less than 5mm of preload, but that's all that is, a guess.

[rodantking]

Thanks RedBird

[HERBXX]

Let us know how it works out as i'm thinking you need to at the 15mm of preload I always thought of preload is setting how much weight needed to be on the spring before it started to move. For example if your preload a 1kg/mm spring by 10 mm, you would have to have a 1Okg force on the system for the spring to start to move .

Case 1

So if you the same spring as above with 10mm of preload and a 20 kg force( yes i know kgs are for mass but anyway) The first 10 kg would be covered by the preload, the second 10kg would cause the spring to compress 10 mm ) So 10mm of sag.

Case 2

15 mm of preload, same 20kg mass, The first 15 kg would be covered by the preload , leaving only 5 kg to becovered by the spring movement , so the spring would move only 5mm

If i'm looking at this this wrong someone please explain it to me .

Thanks

Herb

[Pete in PA]

I'm in the middle of my Hyperpro install, Rear spring is done and I'll be in my forks next.

I didn't try to do any math, started with a 1in. spacer and cut it down once and it was perfect with thestock springs.

[jrdxx]

Another point to keep in mind is that in order to keep from acquiring a collection of spacers that are too short, start with a spring spacer dimension that is clearly too long, and gradually reduce the spacer length until you reach your desired static sag setting. Like you said, adding 15mm is probably too much to achieve your target sag, but it probably wouldn't be a bad place to start, either.

[Pete in PA]

OK now that my stock stuff is out.

I added a 1 in. PVC spacer on top of the factory spacer and spring to get 1.5 in of rider sag on the front end. I'm 300lbs.

[danzig69]

How much time does it take to try different spacer. If the starting point is the mesurement of the actual sag, till the mesurement of the sag with the new spacer? A realistic time, not a race time.

Do you need to remove the fork from the bike to try different spacer?

[Involute]

No need to remove the forks to change spacers. Do one side at a time. Take off one of the Handle Bars. Remove the top nut from the Fork. Pull out the old Spacer. Put the new Spacer in and button it all back up.

Repeat on other side.

Should take 15- 20 minutes if you don’t hurry.

[HERBXX]

How much time does it take to try different spacer. If the starting point is the mesurement of the actual sag, till the mesurement of the sag with the new spacer? A realistic time, not a race time.

Do you need to remove the fork from the bike to try different spacer?

If you alread have the spacer and the front wheel in the air, or some one to hold the back down , less then 15 minutes to change 2 spacers .

You only have to remove the caps from the fork tube , then the cap from damping rod, swap spacers then assemble.. mabe 20 minutes the first time .

[HERBXX]

If one was to cut some delrin or some other kind of plastic discs the same size as the id of the fork and the drill a hole in the center with a slot to the outside edge , you could slip one of more into the fork above the spacer to easily adjust your preload .

[rodantking]

sounds like a lot out work. If you want it for two-up riding, why not just have two sets of spacers? I don't see myself pulling the caps on the road to go from sport to turing.

[HERBXX]

I had meant to it help with tuning , not as a roadside change , The sloted spacers would cut the time it takes to change the preload in half.