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Shock pump

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Shock pump

Unread postAuthor: shud_b_rite » Tue Feb 06, 2007 4:02 am

I just came across a shock pump that is used for mountain bike shocks while I was searching on the internet and to my surprise I found out that some are able to go up to 400psi!.

I have already searched this forum and have read that people say they take a lot of pumps to fill a chamber, but no where on this site does it say how easy they are so you cant tell me off for asking this question.

I have found that many bike pumps become extremely difficult to pump above 80psi and I end up breaking the pumps because I use too much force on them (even ones that are rated to go up to 125psi).

So can someone please tell me that has used a shock pump before, how difficult is it to pump up to say 150psi? Do you need to be super strong to pump it? And what type of fitting do they have on them, can it be attached to a shrader valve?

Any info would be great because I don't think many people know about shock pumps (i didn't and I'm not that much of a newbie). I am planning on using a foot pump to pump my chamber up to 90psi, then using a shock pump to pump it up to 150psi.

Dam i write heaps, I got a bit carried away there.
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Unread postAuthor: CpTn_lAw » Tue Feb 06, 2007 4:56 am

i have a mountain bike pump, i didn't know it was called a shock pump... mine is easily pumped at 100 psi, then a little more difficult until 160, and after, you need to rest your entire weight on it to go up to280-300 psi...but last time i went at 330 psi, it cracked.
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Unread postAuthor: Hotwired » Tue Feb 06, 2007 6:06 am

Shock pumps have a much thinner piston and air chamber than a regular pump so you can get a higher pressure from the same force. The drawback is that it only pumps very small volumes of air at each stroke.

I'd say you're wasting your time buying a shock pump just to reach 150psi.

I have a track pump (it stands on the floor and you pump a T shaped handle), it has a gauge that reads to 160psi. I can get that pressure without having to do much more than firmly push down on it and I'm not a particularly heavy build.

It also pumps a hell of a lot more than a skinny shock pump.
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Unread postAuthor: CpTn_lAw » Tue Feb 06, 2007 6:13 am

yeah, high pressure pumps have a contact surface a lot smaller. I prefer talking in bars for this, but, for example, if your pump has a 1 square centimeter surface, pumping to 10 bars, (150 psi) , you will only need a 10 kilograms pushing to pump. mine has a 3 square centimeter surface...
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Unread postAuthor: Hawkeye » Tue Feb 06, 2007 8:35 am

They are really only useful for pumping a tiny chamber to high pressure or topping up after reaching say 160 with a track pump.
I compromised and built my own pump. Using 3/4 inch copper as the cylinder, it is easy to find fittings that will make a good piston. It is also the right size to allow fairly rapid and easy filling to 200+ psi.
I'm surprised more people don't make their own pumps. It's no more complicated than making a piston valve.
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Unread postAuthor: CpTn_lAw » Tue Feb 06, 2007 9:44 am

I was thinking of building one...in a 8mm copper pipe. i like small caliber highpower pellet guns...
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Unread postAuthor: Hotwired » Tue Feb 06, 2007 12:16 pm

8mm... :?

But 8mm is a soft type, it'll distort fairly easily.
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Unread postAuthor: shud_b_rite » Wed Feb 07, 2007 12:04 am

Ok thanks for everyones info.

I have 1 more question. Can most shock pumps be attached to a shrader valve easily?
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Unread postAuthor: Hawkeye » Wed Feb 07, 2007 8:46 am

They attach even better than a typical bike pump because the fitting actually screws onto the schrader. Still, I wouldn't recommend one unless you are building a tiny calibre gun with a small chamber
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