Rear Shock pressure

[Cruz Addict]

ok guys i am a bit confused, i have recently mad the move to a soft tail and purchased a cheap shock to get the bike ridable, if i was to go on feel, in terms of not knowing what the hell i am doing, i would have set it at 250 odd PSI, this however is the max the shock should be pumped to so am confused, how soft should it be? oh its a rock shox air R shock and i weigh in at 85kilo's. any advice is welcome.

[Mecnic]

Ball park your weight in pounds

[Guest Iron]

well the rule of thumb is you need 20% of the overall travel in sag, what ever that is will determine your pressure.sit on the bike with your feet on the pedals leaning against a wall slowly get off not to compress it further and measure how far it has compressed if more than 20% pump a bit if less reduce pressure.

[Stevief]

ok guys i am a bit confused, i have recently mad the move to a soft tail and purchased a cheap shock to get the bike ridable, if i was to go on feel, in terms of not knowing what the hell i am doing, i would have set it at 250 odd PSI, this however is the max the shock should be pumped to so am confused, how soft should it be? oh its a rock shox air R shock and i weigh in at 85kilo's. any advice is welcome.

Double your weight and work from there, so pump it up to 170 psi. That should sort it out

[Top Fuel]

well the rule of thumb is you need 20% of the overall travel in sag, what ever that is will determine your pressure.sit on the bike with your feet on the pedals leaning against a wall slowly get off not to compress it further and measure how far it has compressed if more than 20% pump a bit if less reduce pressure.

+1

[Underachiever]

Ball park your weight in pounds

 

Yep, runs my Fox RP 2 at 165. Had a great Epic on that setting.

[specialized7]

well the rule of thumb is you need 20% of the overall travel in sag, what ever that is will determine your pressure.sit on the bike with your feet on the pedals leaning against a wall slowly get off not to compress it further and measure how far it has compressed if more than 20% pump a bit if less reduce pressure.

This is the correct answer.Some front forks have a + and - chamber and that becomes a little more complex.Bottom line is forget the pressure and make sure you have 20 to 25% of total travel as sag!!!

Edited February 23, 2011 by specialized7

[Sawdust]

Make sure the shock is in the open position when you check the sag. Must not be on pro-pedal or locked out. 250PSi is freakin high. If you have rebound, set it slightly slower if you get pedal bob. The slower rebound will reduce the amount of boing-boing.

[Cruz Addict]

awesome thanks guys, have set at 190 as it felt a bit too soft at 170 and feels great. thanks for the help all.

[Headshot]

what bike is it on - the suspension design makes adifference too?

[LazyTrailRider]

what bike is it on - the suspension design makes adifference too?

 

It makes all the difference in the world, I actually couldn't believe how many of you don't even mention this. C'mon guys!

 

It's all about leverage (and volume in the case of an air shock, or spring rate in case of a coil). A bike which gets 120mm of travel has more leverage onto the shock than a bike which has 100mm travel, assuming it's the exact same shock. So, it needs more pressure to offer the same resistance to compression forces than the shorter travel bike. In case of coil, it needs a harder one. In case of an air shock, if the shock has a proportionately higher volume, the pressure could stay the same with the same effect.

 

Suspension designs use different methods (pivot and mount locations, linkages, etc) to affect how much travel and thus corresponding force is pushed onto the shock.

 

Short answer then: it's impossible to determine the correct pressure for a shock outside of knowing it for an exact model of bike with an exact model of shock.

 

That's why the only generic answer possible is the sag one, because it's proportional in percentage terms and not dependent on other exact factors.

Edited February 25, 2011 by Martin Hattingh

[drugslinger]

c if this helps

 

75kg - 110psi - 5-6 clicks counter clockwise (rebound)

85kg - 120ps1 - 5- 6 clicks

95kg - 130psi - 7-8 clicks

105kg - 140psi - 7-8 clicks

 

should give you 20-25% sag.

[LazyTrailRider]

c if this helps

 

75kg - 110psi - 5-6 clicks counter clockwise (rebound)

85kg - 120ps1 - 5- 6 clicks

95kg - 130psi - 7-8 clicks

105kg - 140psi - 7-8 clicks

 

should give you 20-25% sag.

 

On your bike it may give you 20-20% sag, but I guarantee you it won't on my 140mm bike, and neither would it on a DH bike with 240mm, or a Scalpel with 3mm of travel. Like I said, all bikes are different, there is no standard pressure table.

[drugslinger]

On your bike it may give you 20-20% sag, but I guarantee you it won't on my 140mm bike, and neither would it on a DH bike with 240mm, or a Scalpel with 3mm of travel. Like I said, all bikes are different, there is no standard pressure table.

 

quite rightly so - these are appriximate settings for the 120mm fox rp2 shock