soft forks

[caps 999]

of the front end on the 480 has allot to be desired so im wondering if any one knows of ways to harden it up with out replacing springs as im only 89kg with gear so mabye spacers and hevier oil might do it any suggestion would be good

[LWC82PE]

you have just about answered the question your self try some air maybe.

[caps 999]

i was thinking if anyone could think of any valving but that seems ok

[LWC82PE]

from reports i have heard, emulators do stiffen up the forks. i have known people that have  fitted them and then no longer need to run air.

[Tim754]

Perhaps half a cup of cement or a viagra in each??   Caps have a chat to Yss I believe replacement springs/Damping valves are a fairly cost effective item.

[evo550]

Capps
Have you set up your sag ?
both static and race sag are the first places to start.
Static sag should be around 15mm and race sag about 100 to 110mm.
Static sag is measured with bike on stand, find two points to measure between, then take bike off stand, bounce the rear end up and down a couple of times then measure the same points. do this a couple of times and the difference should be about 15mm.
Then do the same thing but this time with you and your gear on the bike, the difference shopuld be about 100mm.
Now here is the tricky bit, you will need to adjust the spribng preload collar on the shock, if when you have adjusted it to get 100mm race sag you remeasure your static sag it is LESS than 15mm you will need a STIFFER spring, if it measures MORE than 15 mm you will need a softer spring.
 You will need to get your spring weights right first, nothing else will work properly until this is sorted.
Ahhhh this has got to do with your shock, so all these measurements are done on the rear end.

[brent j]

I've stuffed around with all sorts of combinations in my forks and reached the following conclusions, right or wrong.

Use heavier springs, heavy enough to hold the bike up. Total weight of bike and rider /20 is a good starting point.

Adding spacers will give a stiffer/harsher ride initially but the forks will still be too soft.

Air, to me is just another way to compensate for incorrect spring rates and poor damping

Going to too heavier oil will just make the forks sluggish.

PD valves/ emulators will give you low speed damping but be much softer during high speed movement.

The right springs and damping valves are the way to go, my three cents worth (allowing for inflation!)

Brent

[caps 999]

well ive now purchased some hevier pogressive rate s[rings these should solve my woes

[Ji Gantor]

Hi Brent J,
When you say "Total weight of bike and rider /20 is a good starting point"
Do you mean to add 20 kilos or divided by 20?

This was a great tech posting well done. I think it may have been worth 5 cents.


Ji

[Lozza]

evo I you have it arse about in your summary, to realise static sag you have to have a full extention figure(with not weight on the spring) and increasing the pre-load  will always reduce the free length of the spring,it won't be a true indication of the spring rate. A far easier gerneral rule is a Sag= Total travel divided by 10%/30% rule say you have 100mm total travel, 10% of the travel is taken up with the weight of the bike(static sag) and 30% of the available travel used with the rider on board. A cable tie on the shaft is the easiest way to measure this.Brent is 100% on the fact that air and preload adjustment is no a substitute for the correct spring rate. Also chopping coils off springs doesn't just make it shorter it increases the spring rate

[evo550]

That's what I said lozza
Static sag is measured by first having bike on stand(with rear wheel off the ground) measure between axle and seat bolt, then take bike off stand and again measure between first two points, this should measure about 15mm difference from the first measurement.(give or take a few mill, it's best to do this a coulpe of times and average out the measurement)
Then do race sag settings (with gear on and on bike) at about 100mm, again give or take a few mill.
If you can't acheive both of these settings at once then you will need to change spring rates.
If race sag is then set at 100mm and static sag is LESS than 15mm you will need a STIFFER spring
If race sag is then set at 100mm and static sag is more than 15mm you will need a SOFTER spring.
Some people make the mistake of assuming to little static sag requires a softer spring, when in actual fact it's the other way around.
Think about it and get back to me.

[evo550]

He was, the reason i mentioned the rear was that if sag hadn't been checked and was currently 70mm then it would give and unbalanced weight bias to the front of the bike, giving the sensation of a soft front end, when in fact it was a hard rear that was the problem. That's all

[caps 999]

rear is fine for the minute just the front is hopeless

[brent j]

I'll really stick my neck out here, this is something I wrote up a while ago.

I don't mean to hijack your post CAPPS but it might give you some ideas.

Wasp, thanks for your comments, just don't tell Walter I'm trying to give suspension advice And I do agree with the comments in your email!

Front suspension.

You needed to separate the two suspension functions, load carrying (springs) and control (damping).

Spring selection. ( This is from Works Performance) You need the total weight of you with your riding gear (in lbs). Be honest as any false modesty here will result in the wrong spring rate!!

Weight your bike (again in lbs), add your weight to the bike and divide the total by 20.
This will give you a very good STARTING POINT for the spring rate for your fork springs in pounds/inch.
For a road bike or 10-12” travel MX multiply by 1
For 8-10” travel MX multiply by 1.1
For 6-8” travel MX multiply by 1.2

Once you have found the required spring rate fit the springs with 0-5mm pre load NO MORE!!!!
With the bike sitting upright on it’s suspension the forks (and rear end) should sag between 6-10%. I prefer 10%
Now sit on the bike with your gear and it should sag 25-30%. I prefer 30%.

Pre-loading springs.
This is a definite no no.
If you have a bike that needs a 30lbs/in spring and you have a 20 you may think “oh well I’ll just pack the spring up a bit”. Bad move.
Assuming the bike will sag 1” on a 30lbs/in spring. The spring is under 30 lbs pressure as it sits.
Using a 20 with preload in this case would need about ½” then the bike would make it sag a little over and inch because the spring rate is lower.
Start moving the suspension through its stroke and the 30lbs spring takes 30lbs more to move each extra inch.
1” is taken up with static sag (30lbs) then 60lbs, 90, 120, 150, 180, 210, 240, 270, and finally 300lbs for the last in, assuming 10” travel.
Do the same with a 20lbs spring with preload. 1” sag takes it to 30lbs (20lbs spring and ½” preload) then 2” 50lbs, 70, 90, 110, 130, 150, 170, 190, 210lbs for the last inch.
This spring will ride about as a 30 initially but will bottom very easily. Simple you say, preload it a bit more. OK we’ll add 1 inch more preload and try again
With 1.5” of preload the 20 pound spring now sits static at about 50lbs. so no sag in the front at all. Move it 1” and it pressure is now 70lbs then 90lbs, 110, 130, 150, 170, 190, 210, 230, 250, 270.
Where the 30 only took 30lbs to move it initially the preloaded 20 now take 70 so you have a harsh ride but it will still bottom out as the fully compressed rate is still less than the 30.

GET THE RIGHT SPRINGS


Standard damping

Most of our bikes have damper rod forks with fixed damping orifices. These can be made to work at either high or low shaft speeds (not related to bike speed) but not both!
If these forks have enough restriction to provide low speed damping they will rip your arms off on sharp edged bumps which generate a high shaft speed. The forks just will not move fast enough.
If they are set for high speed damping then they will wallow on slow bumps and dive under brakes.
The manufacturers made the damping a compromise which really means they don’t have enough low speed but too much high speed damping.
If they used the correct spring rates then the forks would be even harsher as the high speed damping would add too much resistance.
As well as compromising on damping they went a bit soft on spring rates to remove the harshness.
I’ve seen air assisted springs, negative springs, low spring rates with lots of preload but like most compromises they seem to address most things badly.



I am using Race-Tech cartridge emulators in my current bike but do have a set of YSS PD valves in a second but unfinished bike. I have not tried these yet but I believe the YSS valve will work at least as well as the Race-Tech product.

Both units use a small hole in the spring loaded top plate to control low speed damping and small movements.
The spring loaded plate controls mid and high speed damping.
There are different rate springs available for this and the spring preload can be altered.
Rebound damping is controlled by the oil weight.

Oil height is important. As the forks compress the air space reduces and the compressed air assists the spring. By increasing or decreasing the oil height you can soften or increase spring pressure in mid stroke and above and increase bottoming resistance. Low speed damping can also be used to increase bottoming resistance.


I use two online spring calculators to measure my spring rates. This was I can find springs at wreckers etc and find their rates.

http://www.pontiacracing.net/js_coil_spring_rate.htm

and this one to find rates with two springs

http://www.proshocks.com/calcs/2spgrate.htm


I’m not saying this is gospel but I’ve talked to people with suspension knowledge and researched everything I can find. Then I’ve gone out and played with settings for hours at a time.
My suspension settings will probably never be finalised as I keep finding improvements. I’m probably the slowest rider out there but one of the most comfortable.
I’ll try to copy and maybe post a few seconds of film from Conondale last year. Four bikes come over the main straight drop off. Three hit the deck and wobble around, one just lands so softly, that one’s mine

Brent

[Ji Gantor]

Thanks Brent J.
That is just magic.
Thank you for sharing one of your lifes work.

Do you have the video footage of Conondale listed somewhere like You Tube.

Thanks again

Ji