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  1. #1
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    Kronos Spring Kit for Rock Shox Quadra 21r

    Hi Everyone,

    I just recently joined this forum because so many of these post have been very helpful to me over the last couple of months and I figure I would give back a little and post a quick overview of the Kronos Spring Kit (Firm 190lb+) for my old Quadra 21R that i bought on eBay.

    I just recently had one of my MCU stacks crumble inside the fork. I had not replaced them in five years maybe more. The damping wasn't working any more so I just rode the bike rigid. I only do some XC so this was suiting me just fine. I am trying to get into a little single track and figured I would give springs a try, plus they were cheaper than replacing the MCU's.

    They come well packaged:
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    Notice the spacer and the Teflon tape on it. (It indicates to do this if the fit isn't tight on the spring. Really nice that I didn't have to mess with this.)
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    Instructions were straight forward:
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    Here is what they were replacing. I was a bit concerned at first about the stack height not matching up.
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    Grease up the spring using Park Tools Poly Lube:
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    Install the spring with the spacer down:
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    Screw in the topcap and you are done:
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    I haven't taken the bike out on a ride yet since I just got these in this evening. The only comments I have now are that the pre-load adjust makes a minimal difference but the springs seem to fit and everything is smooth when I press down on the handle bars. I will post more information when I finally take a ride.

  2. #2
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    Just be aware that with just springs installed you will have no damping at all. If you compress the fork fast on a large bump, they will kick back just as hard. The old MCU type springs had inherent damping to stop them getting too out of hand.
    Other than that, those Q21r's are in awesome condition for their age. A set of those were my first ever suspension forks, loved them.

  3. #3
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    Thanks Kiwi. I realized about the kick but its a 60mm travel so i dont think it would be much. I'll post back after my next ride.

  4. #4
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    I'm thinking of doing the same procedure. Please let me know how it rides. Does Kronos still sell this kit?

  5. #5
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    So I have now been riding these guys for a while and I love them. I've only done some XC and some pavement riding but the forks are great. I would recomend you take off the lower legs, clean the inner stanchions and grease the outside of the stanchions as well. (I didn't show that on my previous post.) The respond well but they also have a small brake in period (took about 3-6 miles). This kit gave my fork a little more life while I save for an 80mm travel XC32. They are currently still available on eBay.

  6. #6
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    Thanks for the review. I just ordered a pair for my retro MTB. Literally had to dig the MCU stacks out as after 17 years they were completely deteriorated.

  7. #7
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    Please note that Quadra's have plastic corks which may fail suddenly with undamped coil springs even when new and at this point they can be quite fragile. There used to custom corks made out of AL for the older RS forks but I have only read about them in '90s bike magazines.

    On my modified Quadras the corks blew off on a modest downhill trail, I hope that it will not happen to anyone in more dangerous terrain.

  8. #8
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    94 karakorum

    I have the same shocks, purchased new in 1995. I was thinking about getting the kit too, so thanks for the post. They look legit albeit, 20th century tech at best. As far as the "corks" go do you mean those useless plastic turny things at the top? They have NEVER done a thing for me, then again I took my bike on 9 day trip to Moab two days after purchasing them and proceeded to annihalte, but the shocks have always gone up and down so I figured they are doing what they are supposed to.

    I was thinking that if I get the kit I might be able to Frankenstien my "corks" by scrounging some metal or aluminum ones from another better shock.

    Any thoughts? My basic thing is that although these shocks are old and have very little travel, they are virtually bullet proof and have very few moving pieces. New ones have all kinds of breakable failable doo-dads that would leave one virtually stranded on a ride along the the Great Continental Divide Route for instance. The 30 bucks seems a little pricey though but I am cheap. Same bike and shocks for 17 years!

  9. #9
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    I just installed these and they seem fine. I put some Teflon tape around the cork threading to insure it is tight.

  10. #10
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    Quote Originally Posted by chromo72 View Post
    As far as the "corks" go do you mean those useless plastic turny things at the top?
    Yes, they are the only things which will keep the springs in. There was some sort of preload function in them but it did not have much effect when new so they are useless now.

    It would be beyond stupid to continue riding these in any sort of technical terrain. Get nice cheap steel fork instead of this junk and keep riding!

    Sorry for harsh words but these forks should not be in any riders bike anymore.

  11. #11
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    Hi all,
    I realize this thread is old, but I have a question regarding the set of Kronos springs I just bought for my Quadra 21R. Everything seemed to go ok with the install, but when I sit on my bike they immediately bottom out under my weight (I'm 175 lbs and I bought the 160+). I emailed the guy who makes them and got this response:

    "Hi Robert,

    Sorry to hear you are having problems. The usual culprit for the problem you are experiencing is a missing plastic spring seat (or both) that are located on top of the shaft on which the springs sit on top of. If these caps are missing, the spring will slide down the shaft and bottom out. So make sure you didn't throw these little plastic caps away. Hope this helps.

    John"

    Any idea what the "plastic spring seat" is? I have all the plastic parts that I removed from the fork, but none of them seem to fit this description. Thanks!

  12. #12
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    I've got 2 old Bontragers - a '96 with the 21R and a '97 with a Judy XC. The '96 rebuild was completed a couple of months ago but the Judy is in pieces. I had planned to put it back together original but have been looking at these kits on eBay. The Judy does have a spring in it but still has an elastomer. And this thread has me thinking of putting a similar kit in the Judy and then going back to the 21R and putting this kit in it. I'm not going to ride either bike too much but will be riding them. See photos over on the Bontrager thread.

  13. #13
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    Just finished putting the spring kit on my shocks. Talk about made a big difference in the ride. The only thing that I have to scream about. Is cleaning the old stuff out of the tubes. Whatever came from the factory just fell apart inside over the years.

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