50mm Marzocchi preload. Recommended setting please?

[andyman]

My bike has exactly 12 hours on it. I've been reading about the fork bleed procedure, and decided I'd give it a shot and see how well it works out. While I'm in there, I wonder if I should adjust the preload??

I'm a vet C (on a good day), all trails, 245-260 with gear.

Here's a pic of where it is now:

Thanks for any suggestions and commentary.

 

[raisrx251]

You have to measure the static sag while the forks are on the bike. I normally use a zip tie on the chrome part of the fork. Push up and down on the foot peg with your foot and get the bike to rest on its own. Then put the zip tie up at top by the seal, put the bike on a lift and then measure the distance. This measurement should be around 35 mm +- 10mm.

If it has too much sag, you want to move that C-clip closer into the spring to add pre-load.

 

[jmetteer]

LT-racing recommends 5-7mm of pre-load.

Mine is a 250 with different springs but I ended up with the clip on the 9th groove down from the top. Stock it was on the 8th. The springs had settled when they were new and there was no preload so I was getting some clicking when coming down from full extension. Going to 5-7mm of preload fixed the problem.

Later,

 

[andyman]

Ahhhhh. carp. Ok. I reckon I'll be doing that after the fluid change.

Thanks!

 

[ray_ray]

I did the bleeding and it helped by bike greatly in the single track stuff ...no more deflection and it now soaks up the roots and rocks and stuff unless it is really huge....I just blast across that stuff now...

The one thing I had to do differently than was outlined in the magazine was to use a more pliable material than the PCV pipe on the top of the bladder where the air is captured at. I just could not get a good seal there so I cut an old aspirin bottle in half and it sealed around the bladder much better ...

I forgot to set my sag so I'll check mine later and I used 5wt oil in mine as I was looking for softness for woods riding...

 

[andyman]

You have to measure the static sag while the forks are on the bike. I normally use a zip tie on the chrome part of the fork. Push up and down on the foot peg with your foot and get the bike to rest on its own. Then put the zip tie up at top by the seal, put the bike on a lift and then measure the distance. This measurement should be around 35 mm +- 10mm.

If it has too much sag, you want to move that C-clip closer into the spring to add pre-load.

I got the bike all buttoned back up. My measurement came out to 41.6mm. Judging from your number of 35mm +/- 10mm, I should be good to go!

Thanks!
Andy

 

[ray_ray]

Why is the static sag used here? Why is the rider not on the bike when setting the front end sag?

 

[dartyppyt]

FYI,

According to the manual each clip movement represents approx 5mm.

 

[raisrx251]

This effects how the bike turns just like the rear shock sag does. With 41mm the bike will turn sharper. With that much though you may have trouble in turns with the front tire not sticking or the bike being too far down in the stroke and be harsh in the turns. You have to ride it and see for yourself. On one of my bikes I was having a hard time keeping traction on the front tire in the turns. I increased pre-load on the fork spring and it solved this issue. I normally run around 35mm. It is easy to change on your forks and they can be mismatched on where the clip is at.

You really have to concentrate on what your bike is doing on the trail for a lap or two and gather the info. When you hit a log and you get a kick you have to go to the next obstacle and compare it, was it the way you hit it or is your suspension to fast/soft/stiff or whatever. It is hard to do sometimes as normally all you are doing is looking for ways to go faster or not crash. Sometimes you need to slow down and think about what the bike is doing.

 

[dartyppyt]

I guess my questionis: when you clamp the 1 1/2 " pvc tool on the bladder and tighten. It pushes the air out?

 

[jmetteer]

No, It holds extra oil in the bladder. You are basically pressurizing the bladder a small amount.

Later,

 

[ray_ray]

LT-racing recommends 5-7mm of pre-load.

Mine is a 250 with different springs but I ended up with the clip on the 9th groove down from the top. Stock it was on the 8th. The springs had settled when they were new and there was no preload so I was getting some clicking when coming down from full extension. Going to 5-7mm of preload fixed the problem.

Later,

This 5-7 mm seems very small ... Are you measuring the preload in the same method as mentioned on this thread?

 

[jmetteer]

This 5-7 mm seems very small ... Are you measuring the preload in the same method as mentioned on this thread?

No, they are talking about sag measurements and I am talking about spring pre-load only. But pre-load has a direct effect on the sag measurement.

With the fork assembled and the outer tube slid down remove the clip that pre-loads the spring. Let the spring relax completely then pre-load the spring 5-7mm from that position. Each clip position is 5mm.

Here is a photo for reference on the clip...

Later,

 

[ray_ray]

Cool... So UR just using 2 different methods to accomplish the same task?

Why is the riders weight not included here as in setting the rear sag?

 

[jmetteer]

The pre-load is how you adjust the sag... more pre-load = less sag.

Because rider weight affects the spring rate you use.

If you have the correct springs for your weight according to LTR 5-7mm of pre-load should get you the correct sag.

Later,

 

[AttackPug]

I wonder if mine needs a clip postion of preload ? It isn't riding level
( high in the rear ) It seems to pack in the chop coming down from speed

 

[ray_ray]

Not sure on any of UR questions ... Is the rear sage set correct or is it too high?

Setting the clip positions is a breeze .... Just remove the forks, slide down the outer shell to expose the clip, and then move the clip as needed ... anything above the 9th slot should be doable without emptying the outer shell of oil or removing the inner chamber from its base location...

 

[AttackPug]

I was thinking about it during work last night. I may just slide the forks down to level the chassis a little. It only has a couple hours on it so I'll let it break in a little more before I do a bleed or adjust it anymore. I'm the same size as Andy so I'll be watching for his review

So far I really like this bike

 

[ray_ray]

Waiting to break in is a good idea ... Sliding the forks down will change the rake angle ... You make or may not want this ... I slide mine down for really tight stuff but really like them flush as the bike is more stable on the high speed stuff and mine seems to deflect less also..

What bike do you have?

I've been playing with my front and rear suspension and so far so good ... I'm hoping to be able to understand how swap between small track racing and trail riding without too much setup time ...

 

[AttackPug]

300 WR The forks are on the second line I'm sure thats why I have the stinkbug effect. I'll raise it to the first line and test it. ( drop forks raise triple clamps )