modifed 1998 K2 4000 Proflex with Fox rear shock

[crowan]

I was trying to sell my 1998 K2 4000 Proflex because the suspension sucked, and was upset I couldn“t even get $500 for it.  Then I came across this forum and realized I could replace the shock components!  I put a pair of Marzocchi forks on the front and a Fox DHX Air 4.0 shock (7.875““ x 2““, $90) on the back.  I would have liked an 8.5““ but I couldn“t find a cheap one second hand.  I had to grind away part of the mount on the swing arm to make room for the air valve.  I also had to machine some bushings for the upper shock mount: a large sleeve with two centralizing sleeves.  I“ve attached some pics.  The bike now feels really awesome, and the Fox shock really does make it feel like I“m floating on air.  My only complaint is that the Fox shock seems fairly easy to bottom out.  I wouldn“t want to take any drops bigger than maybe 18““ and land on a horizontal surface - I“m 165lbs.  I bought a special shock pump ($40), and after setting the pre-load pressure, I have the reservoir pressure set almost to max.

[fyrstormer]

1) Yay!

2) Couldn't the shock fit without grinding with the ends swapped? If not, I guess it's no big deal, but it seems like there might've been more clearance with the air valve at the top end.

3) I'll be honest, I'm not a big fan of air shocks. I have an air fork on my newer bike, and even with both fork legs pressurized to 160psi (as much as my handheld shock pump can handle), it still isn't enough to keep the fork from sagging under light braking loads. It's the progressive-spring-rate nature of air springs, I'm afraid. But feel free to cram as much air into the shock as you need, the seals ought to be able to handle it. I see people on other forums asking if putting 250psi+ in their Fox Shox is safe, and the answer seems to be consistently "yes".

4) I suggest leaving the bike outside in the shade for a couple hours prior to pressurizing the shock. One of the truly annoying things about air springs is they change depending on ambient temperature, so you want to pressurize the shock using air that's the same temperature you'll be riding in, not the climate-controlled stuff you have in your house.

[Spokes]

That works but the mod looks a bit drastic. If you had used the Fox Float R,  RP2 or RP23 you could have got 8.465" / 215mm and fitted it with no mods to the frame and swimg arm at all. I bought this this Float R and a RP2 for £70-£80 on Ebay. Excellent shocks work perfectly.

Chris

[StormCrow]

I was in the same boat last year.  I updated my suspension as well.  Mine is a 98 also.

I got a deal on a Rock Shox Pearl and was happy to find, I didn't have to grind anything.

I took a couple photos yesterday on a ride here in the Santa Monica Mountains. 

The size restrictions will likely blur zooming in though.

I put my bike photos over in the regular forum photo thread.

[crowan]

In retrospect, I should have probably gotten a Fox Float, so as not to have had to modify my frame.  Flipping the DHX Air upside down would have required me to grind away part of the upper mount.  I met someone recently with a new Giant with a Float and he is quite happy with his: he also bottoms out his shock routinely (pushes the rubber O-ring to the top of the shaft).  I was motivated to get the DHX Air because I thought it would be more versatile for the riding I do with it: XC, bit of downhill, and some drops.  We“ll see how it holds up!

[fyrstormer]

I miss Stratos shocks. They had coil springs combined with air springs, so you could adjust the preload and spring rate without expecting the air spring to do all the work. Probably the best bicycle shock setup ever.

Since those aren't available anymore, maybe you should switch to a Noleen shock instead: http://shop.noleenj6.com/category.sc;jsessionid=028AB398B7771694452D734D6FC298EE.qscstrfrnt06?categoryId=7

[Spokes]

May be im not as brave as you guys with big drops  ???but ive never bottomed out the Fox Float on my 4000. I set the sag at about 10mm and it performs brilliantly.

Chris

[crowan]

Are you serious?  Try a Noleen shock?  That“s what was on the bike in the first place and it was like riding a pogo-stick!  No one rides Noleen shocks anymore.  Even allowing for some improvements in their engineering over the years I imagine they are worthy of but a garbage can.

[Spokes]

A little harsh i think. To be fair noleens are fine if the shock is in proper working condition, ie oiled and gassed. The pogoing only happens if the seals are blown and there is no rebound adjustment left in the in the shock. Then youre using just the spring. The problem with Noleen shocks is that people dont service them and expect them to last forever, which they dont.

Chris

[fyrstormer]

Are you serious?  Try a Noleen shock?  That“s what was on the bike in the first place and it was like riding a pogo-stick!  No one rides Noleen shocks anymore.  Even allowing for some improvements in their engineering over the years I imagine they are worthy of but a garbage can.

You're new here. Maybe you're thinking of the Noleen NR-1, assuming you aren't confusing the old Girvin ODS (or elastomer) shocks with Noleen shocks. I was thinking of the Noleen NR-4, with compression and rebound damping controls.



I can assure you, this does not ride like a pogo stick.