Spacer length? (Progressive Springs)

[Guest]

Hello again friends and neighbors,

I've got my new Progressive fork springs! \\/

The kit came with a couple of washers and about an 8" length of heavy PVC-type pipe. I weigh about 200lbs, very little 2-up riding. How long should my spacers be in order to give me a firm but not harsh ride? About 2"? Thanks again for sharing your insight.

Thank you for your indulgence,

BassCliff

[Billy Ricks]

Start off with about 2" spacers. Measure the fork fully extended with the wheel off the ground. Then measure again with the bike on the ground and your weight in the seat. When you end up with about 1 1/2" of sag you will be about right on the preload for the street. Sag is the difference between the two measurements. If you like a firm ride and do alot of canyon carving go for a little less sag. Set the rear of the bike up with the same amount of sag as the front.

[chef1366]

Make sure when you cut the pipe that you don't have any angles. If you don't have a straight cut you will have no fun getting the fork caps back on.
You might play around with the preload settings until you find a confortable one for you.

[salty_monk]

I have 41mm in mine I think.... Be careful because Tom MLC's 1000 springs were different to my ones (although mine is a 1000G) although part numbers & forks etc are the same.

The instructions tell you how to work it out anyway.

I weigh 165lb but I didn't notice a lot of difference when I had it loaded up with kit for Yosemite....

You probably won't want a lot more pre-load than me. I would go 2" max. You can always shorten it though I guess!

Dan

[Billyboy]

I'm 220lbs, I used 1.25 inches of preload. I don't think I could've got the caps on with any more. I like the ride. About 1 and a bit of sag. Plenty stiff enough. BTW: They seem to "wear in" after a bit. I have more sag now than before.

[BassCliff]

Cool man, cool. I can't wait to get these parts installed. Right now, if I don't use air my bike rides like a '67 Caddy. :-D

Thank you all for your help.

Thank you for your indulgence,

BassCliff

[bonanzadave]

Im a buck eighty and didnt use any, but I have preload adjusters on top of my forks. Dont you ? My preload & dampening are both on 2. No air and 15 wt oil. My progressive shocks on back have preload set on 2 and they have no dampening adjust.

I dont do crazy in the corners anymore but this setup sucks up rough spots in the road pretty good.

[emjay]

I'm 220lbs, I used 1.25 inches of preload. I don't think I could've got the caps on with any more. I like the ride. About 1 and a bit of sag. Plenty stiff enough. BTW: They seem to "wear in" after a bit. I have more sag now than before.

Some of the increased sag is due to oil break down. Change it often for consistant performance.

[bwringer]

Oil viscosity or breakdown affects damping, but does not affect sag.

Preload spacer length will vary considerably depending on which forks are on your bike, so unless you're certain that you're talking about the exact same model of bike, it's more productive to compare the total amount of initial compression, which will take into account the depth of the fork cap and the amount of spring showing above the fork, if any.

Here's how things ended up on my GS850G. Keep in mind that this is an extreme example. I am heavy (over 19 stone) and I ride quite rapidly. Most people should start with 25-40mm less preload spacer length, and test and adjust to taste.

Total spacer length I ended up with:


Amount this sticks up before squashing it down and screwing in the spacer. This is a nearly impossible task...lots of bad words and struggle.


The happy result: 25-30mm static sag (amount the suspension compresses with the bike upright and moi in the saddle):

[salty_monk]

That's 266lb for the uninitiated....

Picture 2 on mine was level with the top of the fork leg I think.

Dan

[BassCliff]

I'd heard there would be no math!

Thanks for doing the math Mr. salty_monk. 1 stone = 14 US pounds?

Thank you Mr. bwringer for the pictures. I love pictures!

Mr. bonanzadave, I haven't had my fork caps off yet, don't know what's under there. I've just been using air. We shall see.

Mr. emjay, thanks for the reminder to change my fork oil occasionally.

Thank you for your indulgence,

BassCliff

[salty_monk]

If you can't see the preload adjusters from the top then you don't have them.... If like me you just have the air valves showing then that's all there is.

You can make an adjuster (basically a blanking plug cap with a bolt through it to move a large washer up & down) but it's probably OTT for what you need.

Work out the length to get it to the top of the forks & then add a max of 5mm for your weight if I was you.

Dan

[bwringer]

That's 266lb for the uninitiated....

Picture 2 on mine was level with the top of the fork leg I think.

Dan

Dang, I thought I was being obscure, but I forgot about all the Brits around here. #-o

Should've used slugs, drachms, or troy ounces.

I'm big and I'm fast. 'Nuff said.

[salty_monk]

Sorry! Let your secrets out

How are those Avons doing... I'm waiting to see what mileage you get before I decide on those or the demons!!

[BassCliff]

Finally

Hi!

Wow, I can't believe how long it took me to actually install my Progressive springs. Did you notice how old this thread is? Since my seals were in good shape, no leaks, it was really easy to take off the forks, drain them, rinse them with mineral spirits, refill them and install new springs.

Here's a shot of the hardware coming out of the old fork. The stock spacer is 3" long.



I went with the documentation's suggestion of 1.75" spacer. I cut it and sanded it square. I would never have gotten that 3" spacer back in there.



Here's the old springs (top) and the new springs, to show the difference.



I ended up with 1.48" of sag. It's too late to go for a test drive. But I'll let you know.



That old oil was nasty! The new oil was a pretty red. I'll have a full write-up soon.

Thank you for your indulgence,

BassCliff