Rear Shock Bottomed Out

[darnijl]

I was riding Tokai for the 1st time yesterday 'cuz I finally had some free time and a lift..

 

And I bottomed out my back shock like 3 or 4 times.. But on small drops and stuff... I was riding really chilled, no road gaps or big jumps.. Just like small stuff...

 

Now does this mean I'm landing badly - like bad technique?

 

Or should I consider a stronger coil?

 

I weigh about 75Kg, and I think I have the 350Lbs coil on my DHX4 (Kona Stab '05)

 

Helpz

 

I dunno if this makes a difference, but maybe if you can see here.. Coil's a bit compressed already ? Maybe not ? Can that happen over time ? Could that be my case?

 

http://is.pinkbike.com/photo/3820/pbpic3820122.jpg

 

 

 

[darnijl]

Or the coils been ... Uhhh ... made uhh smaller by the cog...

 

So mines much more compressed than this one:

 

http://www.perthmtb.com/files/fox%20dhx%204.0.JPG

 

[Capricorn]

 

 

Darnilj: have you set you compression all the way to max? if you say it's small stuff, then it shouldnt be a problem checking if you bottom out off say a curb or a low balcony.

 

Set it compression to min and then to max. see what the difference feels like.If nothing, then you shock needs some maintenance. No oil squirting around etc?

out of interest, what's your sag setting? Sag is generally set according to the type of riding: DH or XC etc. For DH IIRC, it's between 30 - 35%. Fox states on their website that if you have to turn the spring preload nut too many times, then it's recommended to go with a higher spring rate. Check on fox's website: their guidance for setting your rear shock is quite straightforward. They also have a little online application that gives guidance as to the required spring rate depending on your weight, wheel travel, shock dimensions etc..

Give it a smash and let us know.

 

Capricorn2009-10-18 05:32:29

[Capricorn]

this from Fox's tech center:

 

Bottoms, soft throughout travel:

Causes: Initial spring rate or preload too low; spring too progressive

Solutions: Add air pressure or increase spring preload

Source

[Capricorn]

go here , accept the conditions of use, and select from the menu on the left "Rear Shock Spring Rate Calculator". Input the required parameters on the right, and click calculate. That will be a very good indicator if your current spring is suitable or not.

 

However, even though the calculator gives you ?a certain spring rate, you find that most peeps select a spring rate based on personal preference. Some like it higher or lower depending on their riding style. A nicely clued up mechanic, or an advanced rider might be better suited to provide that sort of subjective guidance, without you having to buy 3 or 4 difference springs just to test. If you're friendly with your LBS, maybe they can hook you up with some springs they have lying around. try each for a few days and then decide which spring rate better suits you.

but start with that calculator.

[darnijl]

Wow. Whatta mind blow. Thanks Capricorn, I'll see what I can do..

 

"what's your sag setting?" - No idea

 

"Set it compression to min and then to max" - How?

 

[Mecnic]

 

 

I weigh about 60kgs and ride a 400lbs spring I personally think that a 350lbs may be a bit light for you as you stated weighing in at 75kgs

 

the 350lbs means it takes 350lbs of force to compress the spring one inch taking the leverage ratio in to consideration that isn't such a high number and therefore you may need a stiffer spring.

 

Compression may help but if the spring itself is to light you may run the risk of blowing the shox itself after repeated bottoming  out as all compresson does is reduce the diameters of the valves which dampening oil flows through

 

Increasing the air pressure only increases the amount of force needed to begin the initial shox movement and will not help with the bottoming problem

 

Hope you come right