Mountain Biking - Difference between PSI and POUNDS?

Please help me clarify something. I am being told that I am putting to much pressure in my shock. The manual calls for 52lbs, so I am putting 52psi(based on my shock pump) into my MX Comp Pro. I am trying to explain that there is no difference between the two. Please correct me if I am wrong.

You are correct. There are two (2) different types of valve systems on the forks we all have nowadays. Low pressure (PSI) & high pressure (PSI). Yours is apparently one of the "high" pressure systems....

Mine calls for about 25 psi.

You are correct. There are two (2) different types of valve systems on the forks we all have nowadays. Low pressure (PSI) & high pressure (PSI). Yours is apparently one of the "high" pressure systems....

Mine calls for about 25 psi.

Well it is based on body weight and I am 190. I am being told by the certain member that I need 0-15psi and 45-52lbs. Lokk for yourself here http://www.bikeforums.net/showthread.php?t=147360

Who cares what anyone else tells you.... I sure don't....

Just do as the manual instructs.

Good Luck!

Who cares what anyone else tells you.... I sure don't....

Just do as the manual instructs.

Good Luck!

I was just wanting to prove my point.

Point Proved....

By me, anyway.

What shane is trying to say - I think - is that to put 45-52 pounds of weight on your handlebars your shock needs the 0-15 PSI (what we commonly refer to as pounds for short).

Of course, I may be wrong.

Some shocks do have high pressures; my Fox Float runs about 100 psi for my weight.

Or just replace your MX comp pro with a better fork.

Or just replace your MX comp pro with a better fork.


I bought what I could. Some people can't afford the best. Thanks for the kind words.

Or just replace your MX comp pro with a better fork.
whats wrong with the MX comp? mine does me just fine

According to the chart, you need about 50psi. I've got a Manitou fork that runs more than 2x that, along with a Fox Float shock. Some systems use low pressure, some use high. How does the fork feel at that much pressure?

Please help me clarify something. I am being told that I am putting to much pressure in my shock. The manual calls for 52lbs, so I am putting 52psi(based on my shock pump) into my MX Comp Pro. I am trying to explain that there is no difference between the two. Please correct me if I am wrong.

It seems to me that no one has really answered the original question. PSI stands for "pounds per square inch", and it is a unit of pressure. Plain old pounds (lbs) is a unit of mass which is sometimes also used for weight (not the same thing if you are being pedantic).

Your manual calls for a pressure of 52lbs, but this is probably just the manual writer being lazy, or inaccurate, in the units being used. The number is probably correct (I don't know your fork) but the pressure should almost certainly be 52 PSI. So you have been using the correct pressure.

What shane is trying to say - I think - is that to put 45-52 pounds of weight on your handlebars your shock needs the 0-15 PSI (what we commonly refer to as pounds for short).

Of course, I may be wrong.



Not wrong - thank you.

As I tried to explain, the 'Zocchi manual shows two different lines - one shows weight measured in POUNDS (weight on the bars - NOT PSI), vs. preload air pressure (measured in PSI - pounds per square inch).

Again, you add 0 - 15 PSI to achieve a sag of 20 - 25% of total available travel. The MX COMP series that started all this, only has one air valve. Maybe someone would like to tell me why the manual shows 0-15 PSI of preload, and 30 - 65 pounds positive air? It can't be both.....there's only one air valve on the Comp. :rolleyes:

Again, adding 0 - 15 PSI gives you 30 - 65 pounds of positive air.

BAR is the metric version of PSI.

[edit] a unit of pressure equal to a million dynes per square
centimeter

Not wrong - thank you.

As I tried to explain, the 'Zocchi manual shows two different lines - one shows weight measured in POUNDS (weight on the bars - NOT PSI), vs. preload air pressure (measured in PSI - pounds per square inch).

Again, you add 0 - 15 PSI to achieve a sag of 20 - 25% of total available travel. The MX COMP series that started all this, only has one air valve. Maybe someone would like to tell me why the manual shows 0-15 PSI of preload, and 30 - 65 pounds positive air? It can't be both.....there's only one air valve on the Comp. :rolleyes:

Again, adding 0 - 15 PSI gives you 30 - 65 pounds of positive air.

NOOOOOO positive air...................forget it your to thick headed to see.

whats wrong with the MX comp? mine does me just fine

There is nothing wrong with your fork. The MX comp is made for a certain kind of riding and it is not the kind that dirtyamerican does, so it is junk to him. The MX comp series has great reviews and preforms great on the trail. It might not be able to take huge drops but you don't do huge drops on a XC bike.

NOOOOOO positive air...................forget it your to thick headed to see.

Its a shame, brilliant people like us having to deal with such lowly life forms. :p

There is nothing wrong with your fork. The MX comp is made for a certain kind of riding and it is not the kind that dirtyamerican does, so it is junk to him. The MX comp series has great reviews and preforms great on the trail. It might not be able to take huge drops but you don't do huge drops on a XC bike.
I dont do huge drops either but I do hit huge rocks and roots at full speed. unintentionally , but still.
this fork seems better at the big hits than the small ones for me. Im 200 pounds plus gear and run at 40 PSI

Not wrong - thank you.

As I tried to explain, the 'Zocchi manual shows two different lines - one shows weight measured in POUNDS (weight on the bars - NOT PSI), vs. preload air pressure (measured in PSI - pounds per square inch).

Again, you add 0 - 15 PSI to achieve a sag of 20 - 25% of total available travel. The MX COMP series that started all this, only has one air valve. Maybe someone would like to tell me why the manual shows 0-15 PSI of preload, and 30 - 65 pounds positive air? It can't be both.....there's only one air valve on the Comp. :rolleyes:

Again, adding 0 - 15 PSI gives you 30 - 65 pounds of positive air.

I do believe the 0-15# thing is for the MX COMP ETA spring fork. The 30-60# is for the air sprung MX COMP, no ETA fork. Went through this same thing when I got my MX PRO ETA fork. The manual sucks.

PSI is an acronym for POUNDS per SQUARE INCH. It is used to measure pressure, ie the air pressure in your shock. Many people abbreviate pounds per square inch with "pounds." They are the same thing.

I do believe the 0-15# thing is for the MX COMP ETA spring fork. The 30-60# is for the air sprung MX COMP, no ETA fork. Went through this same thing when I got my MX PRO ETA fork. The manual sucks.

No the manual is fine, it is the person reading it with the problems.