Taiden

SUMMARY:

2002 K2 ZED SE with RST forks, never rode hard, stored inside until a few months ago. It was outside in the rain four times and in the snow two times. The shocks always worked well enough for me. I was riding it today and brake-fluid-smelling stuff started spewing out the top and bottom of the forks, and now it bottoms out incredibly easily. Can I rebuild / refill it with shock oil / replace it for less than $75?


STORY:

I've got this older K2 ZED SE (2002) with the RST front forks. I rode it soft on packed dirt trails for a few years then hung it up in my garage. Just this year I started commuting on it. Point being, it hasn't been ridden rough. It was never left out in the rain.

Then I went to college, the only place to store the bike was outside and it sat through a few rain storms and a couple snow storms. The bike was ridden once or twice during this time, and performed well to my light-riding standards.

Anyhoo... fast forward two months of basement storage. I decide I want to start getting into heavier urban riding, because the college I transferred to has lots of great stairs, hills, benches, low rails, plus packed dirt trails.

Today I was getting it ready by cleaning and lubricating my v-brake pivots among other things. When I got the bike all back together with perfect smooth brake action I started doing some hops in place.

I noticed that after the 8th hop the shocks were significantly less bouncy. Soon they started bottoming out, having reached their maximum amount of travel. I got off the bike and checked the forks. There was a dull dark orange liquid all over the top caps on the forks and all over the ground coming out the bottom of the forks. It smelled like some kind of fluid, like brake fluid, or ATF.

I'm a poor college student, so it looks like unless there are decent forks out there for under $75 I'm going to be S.O.L. Instead I'm asking you guys for any tips for how I might troubleshoot or revive these forks. I am in school for mechanical engineering and I understand automobile suspension systems, so if it's something that doesn't require a machine shop I should be able to do it. I NEVER expected to see fluid coming from the top AND the bottom. It looked like the oil resevoir was simply capped off with something similar to bar end caps.

LarDasse74

I would not be surprised if the fluid coming out of the fork was not oil or hydraulic fluid - just filthy oily rusty water. I can not guess why the forks are bottoming out more often now. THose forks are not designed for the type of use described anyway.

AFAIK, very few RST forks from that era had any type of controlled damping - and I do not know of any that had oil damping - they were trying to use air damping on their higher end forks up until 2002 or 2003, I think.

I may be wrong.

PS. Get some tough rigid forks... maybe like Surly instigator... a lot cheaper than any suspension.

Taiden

Good point. I bet it was just rusty water. I'll clean it all out.

I can't figure out how air would be escaping.

Is it just a compressible cylinder with some kind of compressed gas? Is it something that can be "recompressed"?

Retro Grouch 

Most, if not all, of the budget forks have an elastomer spring. If you drop the slider portion of the leg you'll find what looks like a plastic dowel. When they are new they compress when you hit a bump. As they age they gradually harden and won't compress as much.

cobba

I found a reference to a K2 Zed SE but it was a 2000 model, can't find any reference for a 2002 model.
2000 K2 Zed SE: https://bikepedia.com/QuickBike/BikeSpecs.aspx?Year=2000&Brand=K2&Model=Zed+SE&Type=bike

Manual for the RST fork on the 2000 model bike:
Part 1:https://www.rst-europe.com/manuals/M-F-P1.HTM
Part 2:https://www.rst-europe.com/manuals/M-F-P2.HTM
This fork has uses some grease on the springs but it doesn't have any oil in it.

You shouldn't be using that bike for the style of riding it's currently being used for, a cracked or snapped frame will be the next thing to go on it.

LarDasse74

Elastomer springs sometimes split and almost all of their ability to suspend the rider.

Other possible causes of forks going soft are broken steel springs, steel springs stuck halfway down in their travel, loss of compression damping (like a blown air or oil damping mechanism).

To Taiden: If you want to avoid maintenance hassles and other problems with your fork I have one word for you: "RIGID"

cbchess

look for an older coil fork on ebay like a Marzocchi from 2001 or 2002 should be right in your price range.

I would also suggest rigid for cheapness - and I would recommend that you throw away your old forks - they were crap 9 years ago and now they are super old and busted crap - not worth $1 to fix.

Taiden

Yeah, these forks are busted beyond belief.

cobba: you found the right bike.

Is that a bike worth keeping and replacing the forks? I will be doing medium/light trail riding and some urban hooliganism. What is the quality of the components?

Taiden

Bumping this up again. I've decided to get a bike set up for campus hooliganism. I can either use this K2 frame and components and replace the fork, or I can just start over completely.

I've considered a BMX bike, but honestly I feel they are way too small for me to be able to move easily. I can hop way easier on my K2 than on my friends diamondback joker BMX bike. Maybe it's just because it's a crap BMX bike.

Also, this bike will be living in the bike racks at school, and I'm sure some of you have seen what can happen to those bikes. For that reason using my existing K2 is an attractive solution...

Taiden

Today I pulled the forks apart. One of the plastic pieces that threads into the spring and gets bolted into the lower part of the fork was completely destroyed. I pulled out all the suspension related pieces and degresed the inside of the forks. I then found copper pipe in my basement that was a perfectly snug fit, cut two pieces to an equal length, covered them with JB weld and fit them inside the forks. I now have converted my suspension forks into solid forks. I actually lost some weight and added some rigidity to the system. I'll be using this setup until it breaks and will either spring for a new bike or just a front fork.

DieselDan

RST means Really Sh*tty Technology.

LarDasse74

Ha ha.

In many ways, RST has always been far behind the main manufacturers... but I don't think they ever really tried to compete with Marzocchi, Manitou, Fox, etc... they are a budget-oriented suspension manufacturer... and for years they were the absolute king of budget suspension (Spinner has replaced them in that role over the past few years IMHO).

If you think RST is crappy, have you ever seen Top Gun suspension forks? Have you ever looked at the websites for the dozens of Chinese and Taiwanese (and various other Asian countries) budget suspension manufacturers? You would be horrified to see the absolute ridiculous crapola that almost never makes it into the Western bicycle market. RST forks are cheap and cannot (and never could) compete with the big names, but they have consistently made affordable, safe, half-way-decent products for their entire lifetime.