Spring Rate Preload and valving!

[Roost1]

Have you ever watched a really smooth rider? They make it look like they are almost floating over everything. For the rest of use we need suspension to compensate for the wrong line or a cased jump for example. This is why the suspension has to be personalized to rider. For me being a woods rider I prefer a spring towards the softer side and control the speed with valving. It may not the best set up for whoops but I hate them anyway so I just pin it and ride across the tops:)

 

[MRW]

When I race a MX track, I tune my suspensions mainly for the turns. In Cyprus, most of our tracks are made of hard clay and rocks with supercross type jumps and tight turns. I definitely go for the following setting:

- relatively hard springs, but with low pre-load,
- moderate low speed compression damping,
- light high speed compression damping.

It seems that the low pre-load (3 to 5mm on the fork springs) keeps the fork plush and more responsive on small bumps. Also, it allows the front end to dive moderately when I set up for a corner (I need that because my KX does not turn if the front end rides too high).

Than the springs get harder as the fork goes deeper into the stroke. This usually gives me sufficient bottoming resistance.

I need moderate low speed compression to keep both wheels on the ground in the turns.

The light high speed damping helps me to reduce "vibrations" in the bar as I ride a high speed section with little bumps and rocks.

For those slippery conditions, I like to run a low air pressure in the tires (around 800gr only). And I install 2 inner tubes to increase the resistance to puncture.

I know lots of people that love this type of setup :)
Rocks, palmetto`s, same differance, both slippery and hard :laugh:

 

[kiwijohn]

Gidday people... I love threads like this! Much like the world famous "Which Oil do you use?" threads, this one is full of fact, fiction, opinion and reality.... awesome!

I have a few questions after reading all of this , so if you have any extra info please feel free to put me on the right track!

Two days ago I bought an 06 RM250 from my buddy after riding a 06 RM125 for 3 months, and before that an 05 Sherco 450 .

The 125 was pretty good in the woods, unless there were steep hills around:( , and the Sherco was great in even the ugliest terrain. But I think the soft suspension made the bike feel heavier than it actually was?!

Question one is: Did the 125 feel good to me because I was heavy enough to break through the MX valving?

The 125 is MX bike set up for - I'm guessing - 150lb riders? While I'm about 93kg (205) plus gear. The Sherco would be set up for an 70 - 85kg (155 - 190lb) rider?!

The 125 spring weights are a mystery to me... but the valving would be MX in set up. The Sherco springs had to be heavy enough to support a heavy bike but had light valving at both ends too.

SO - the question I need to think about for my RM250 is: "If I reduce the valving to a softer setting, like the Sherco, will the heavy springs overpower the valving? Would I be better with softer springs and softer valving (That's my guess).....
Or, if I leave the stock springs in - Will I need to have a my rebound heavy enough to cope with the strength of a stiffer spring?

In my little brain I don't mind if my springs go through the travel quickly to absorb ruts and rocks etc, but I don't want them to shoot me into space on the rebound either!!

Sorry if I sound a little, confused but that's because I am!

Cheers

John

 

[Filthy_McNasty]

Wanna know the damping curve I want? I'll design an inertial valve that reduces damping to near zero under high acceleration. What this would do is let the wheel move freely when it gets a sudden jolt and then smoothly apply damping as the acceleration spike subsides - arresting further wheel motion but avoiding the spike. All this needs to be is a spring and a mass driving a spool valve or perhaps a needle. Put that in your pipe and take a good drag......

.

Isn't that in essence how Yamaha's SSS damping system works?

 

[MRW]

There are forks like/similar to what "mace" speaks of. They are for mountain bikes and perhaps other types of vehicle's.

"Fox" make a set of forks called "f100x" and the have this type of inertia valve system/principle/concept idea going on.
They are old tech. by now(2006), but just the same, they are
cool :)

 

[JimDirt]

New here (my first post and looks like i am reviving a old Poll) , what i have noticed , is heavy springs and really soft valving makes Off-Road riding more pleasurable by keeping the bike up in the stroke yet letting the suspension work so you dont have to , i find since going 2 size stiffer fork springs (while keeping rear spring for my weight) and valving both front and rear very soft , my bike seems to float over most things and does not seem to deflect as much , making rider effort much less work , and making the ride more enjoyable , i used softer Pressure Springs as well (2002 CRF450R and 2006 CRF450X) on both my bikes , i also ride my R on the track , and find this setup works great with only a few clicks to set it for the track i am riding , i am also overweight and older , so the beatings were killing me , with this setup , i can ride longer with less fatigue and arm pump , i wish i had done this sooner