Dropper post pressure

[PaulieV]

I have had some issues with my Specialized Command dropper. Google search suggests a dropper should be pumped to 200-250 psi. Specialized website says this post should be pumped to 30 psi. Why the massive difference?

[guidodg]

30psi max...not sure where you read 200-250psi?

[Me rida my bicycle]

6 minutes ago, PaulieV said:

I have had some issues with my Specialized Command dropper. Google search suggests a dropper should be pumped to 200-250 psi. Specialized website says this post should be pumped to 30 psi. Why the massive difference?

Maybe they made a mistake on the website. All the posts I have used was 280-300psi. Phone a Spez shop they should be able to give you the correct pressure. 

[BaGearA]

5 minutes ago, Me rida my bicycle said:

Maybe they made a mistake on the website. All the posts I have used was 280-300psi. Phone a Spez shop they should be able to give you the correct pressure. 

command posts are indeed 30psi max 

 

 

Don't go over what the manufacturer recommends for their product , i promise they know better.

 

OP your dropper needs A service 

[PaulieV]

Ja, I assume the Spez site is correct, the pressure I was running was clearly waaaay too high, could lose a set of gonads. 

[PaulieV]

21 minutes ago, guidodg said:

30psi max...not sure where you read 200-250psi?

[BaGearA]

25 minutes ago, Me rida my bicycle said:

 

ks post not A command post 

[Kom]

5 minutes ago, BaGearA said:

ks post not A command post 

I had a KS on my Commencal - not the best dropper ive had, and frequently needed topping up. 

Side thought but the cartridge based droppers i.e like the Lyne are just more pleasant to live with on the maintenance front, but frustratingly develop play over time.

[BaGearA]

I'm also a fan os basic catridge droppers , Lyne for example 

 

BUT IF you want to spend some decent money on A dropper get A bikeyoke revive , those things are awesome and reliable as hell 

 

Its as complicated inside as the reverb but has the reliability of A Lyne , and its A light and super smooth action 

[droo]

Pressures will depend very much on which dropper you're running. 250psi in a command post and you'll need SpaceX to retrieve both your saddle and your gonads. 

 

20psi is about the sweet spot. 

[Nuffy]

As @droo said, pressures depend on which dropper you’re talking about, as the designs vary hugely. Pressure = force / area. The Command Post uses a much larger piston (ie. area) than most designs, so to get a force comparable to designs with a much smaller piston (like a RockShox Reverb) you will need a proportionately lower pressure:

250 psi = 250 pounds / 1 inch²

25 psi = 250 pounds / 10 inch²

I don’t know what the actual piston areas are, but the above should illustrate the point.

You can vary the pressure of your Command Post slightly to change the return speed, but stick within the range that Specialized recommends and note that even at low pressures those particular posts are known for their vigorous return.

Edited May 5, 2022 by Nuffy

[madmarc]

On 5/2/2022 at 5:59 PM, PaulieV said:

 

On 5/2/2022 at 6:11 PM, Kom said:

I had a KS on my Commencal - not the best dropper ive had, and frequently needed topping up. 

Side thought but the cartridge based droppers i.e like the Lyne are just more pleasant to live with on the maintenance front, but frustratingly develop play over time.

I've had a KS LEV for over 7 years, run it at 200 psi - the range is 100 - 250 psi depending on the return speed you want - I've only topped it up 3 or 4 times since i installed it. Recently it developed about 15mm of sag I stripped it, did an internal clean and recharged the oil can after a quick course at university of YouTube. Works like a Swiss Watch again.

the only play is a slight, and i mean a very slight, rotate (probably like 0,5 deg) left to right on the saddle which you cannot feel when riding and normal according to KS LEV. (My boet has a Lyne where the rotate movement is more) - If you start to feel it then the 3 thin brass rods at the bottom of the stanchion need to be replaced. 

[guidodg]

agreed on the KS Lev droppers… I have owned 2 and they are excellent, better than any other I have owned and easy to maintain…unfortunately have to sell mine since it does not fit my Epic Evo (30.9)😕

worst dropper I previously owned was the Fox… would get stuck if I torqued seat collar over 4Nm

[Headshot]

LOL, 200psi in a Spesh  dropper - that's insane. Google is not your friend if you abandon logic and don't read what the manufacturer says and rather rely on some git on MTBR.