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  1. #1
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    Replacement front shocks for 1994 Stumpjumper

    I want to replace the Future Shock that came with my '94 StumpJumper. What's a good choice? I'm not looking for a lot of travel, although probably any modern front shocks will have more travel than what I have now. I just want something smoother and more responsive that my aging FS.

  2. #2
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    I've been visiting some manufacturer websites (RockShox, Marzocchi, Fox, Manitou, and SunTour). Problems I've run into:

    • •Lacking fork length info. Only Marzocchi gives the length of the fork from the crown to the drop outs.
      •Hard to track down which shocks support vbrakes. The Marzocchi was pretty good at this. RockShox is a nightmare. In general the websites don't seem to make it clear which ones support vbrakes.
      •Drop out is offset. MY FS shock is not. I suppose this shouldn't end up being a problem, because it just pushes might front tire out an inch or so. Hopefully I won't notice.
      •Shocks are longer now. My current shocks have 80mm of travel and are 410mm long. The 80mm shocks I've been able to get size info on so far are about 455mm long. This is nearly 1.5 inches longer than my current shock. Fortunately my stem raises my handlebars by about that amount, so I can probably get a 0 degree stem to keep my handlebars at the same height. However, 80mm versions seem to be harder to find than 100mm, so I'll probably end up with a 100mm, making the total difference about 2.5".
      •Shocks are heavier. My FS is 1.5kg. Most midrange shocks are in the 2 to 3 kg range.
      •Lots of variations. Some support vbrakes and some don't. They all come in a variant of strokes lengths. Some have tapered steers, some straight, and some support both. There are also variations in the drop outs.

  3. #3
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    Did a bit more research. The only 80mm shock with 9mm drop outs and v-brake compatible I could fine is the Rock Shox XC. The 32 TK version is fairly cheap at $191 retail, and I found one for $129. My only concern with it is the weight. At 2332g it is about 1.5 lbs heavier than my current fork. I might go with a 100mm so I have more options, but then I start to worry about the head angle decrease.
    Last edited by cplummer; 08-26-2012 at 11:03 AM.

  4. #4
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    To be honest, your best bet is eBay - something from that era (90s). You don't want to go over 80mm, and even at that travel, your geo will be jacked up over what it was. 63mm Rock Shox forks from that time would be perfect. If you are patient, there are used forks on eBay that will work, however, most of the forks back then were troublesome even when new (think Judy cartridges blowing) so you may be SOL.
    Geologist by trade...bicycle mechanic (former) by the grace of God!

    2012 Specialized Stumpy EVO 29 HT

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    If I can't get something new that is acceptable, then I'll probably just stick with what I have. The FS still functions, just not that well and I wanted something better. I think putting another vintage shock on there is more trouble than it's worth. I'm pretty sure I'll be sticking with 80mm just to keep the head angle decrease to a minimum.
    Last edited by cplummer; 08-26-2012 at 10:55 AM.

  6. #6
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    You can also just go rigid with a fat front tire set up tubeless so you can run low air pressure. Its another option.
    Geologist by trade...bicycle mechanic (former) by the grace of God!

    2012 Specialized Stumpy EVO 29 HT

  7. #7
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    Quote Originally Posted by TiGeo View Post
    You can also just go rigid with a fat front tire set up tubeless so you can run low air pressure. Its another option.
    I think I'd rather stick with the FS I have than go rigid.

  8. #8
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    I've been unable to find the head angle for my '94 Stumpjumper. I looked in the original catalog, but it doesn''t have geometry information. I also didn't have any luck looking online. I compared the head angle with my son's bike, which I know has a 71 degree head angle. The Stumpjumper is definitely more slack, I estimate by a couple of degrees based on some measurements I took (The Stumpjumper wheel base extends about 1/2" over the length of 15" of fork). It will probably drop down a couple more degrees to 67 degrees by the time I add a new 80mm fork. Isn't that getting in DH geometry?

  9. #9
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    Quote Originally Posted by cplummer View Post
    If I can't get something new that is acceptable, then I'll probably just stick with what I have. The FS still functions, just not that well and I wanted something better. I think putting another vintage shock on there is more trouble than it's worth. I'm pretty sure I'll be sticking with 80mm just to keep the head angle decrease to a minimum.
    When you say, "doesn't work that well", what do you mean? I have the same bike and fork. For the last year it was not working well. When riding on rough trails it would sometimes lock up and stay compressed. Two weeks ago it completely went rigid.

    So I decided I really had nothing to lose by taking it apart. I google searched and found a service manual for the Rock Shox mag 10/21. Followed that and now it's working really well. No special tools needed but having circlip pliers would have made my life easier. Also, without seal puller you want to do this outside and over something to catch the oil.

    In my case, what seemed to be making the fork stick was a scratch on the inner tube. The bushings/bushing sleeves were getting stuck on it. I smoothed the scratch out with fine grit sandpaper.

  10. #10
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    I'd say stiction and lack of responsiveness over smaller bumps. Also, just knowing how far shocks have come in 18 years makes me want to get something better.

    I actually replaced this shock once already, I think in 1996 after a couple years of thrashing. I still have the original shock. It won't compress at all. Maybe I'll experiment on it first before trying anything on the working shock.

  11. #11
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    HEre's a link to the service manual http://www.mtb-kataloge.de/Bikekatal...uals/mag21.pdf


    Let the air out first, once you get the circlip off you can inflate it until the main seal pops loose. I did it over a garbage can ...oil still went all over, but I think it's really the only way unless you can get a seal puller for it.

  12. #12
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    Thanks for the link to the manual. I played around with the my old FS (the one that is off the bike) and learned a few things. The first thing I noticed is that the crown makes the stanchions more slack than the stem. Basically the stanchions angle out more than the stem. One of my concerns was that a longer fork would result in the head angle being even slacker. However, if modern forks all have the stanchions running parallel to the stem, this would likely offset any additional slackness introduced by the increased fork length. The stem would still be more slack than what I have now, but the stanchions themselves would probably be about the same as what I have now.

    I dumped the oil out of one shock. It was kind of a pea green. I think it must of been the original oil. The shock seemed to operate ok. I didn't bother trying to completely disassemble it since I didn't have the tools and it didn't seem necessary.

    I then went on to the other shock and noticed a few differences. First, the air cap nut was badly dinged up, but I could still get a wrench on it. 2nd, the damping adjuster rod was not longer secured. Guess I didn't follow (or have) the instructions regarding not letting the damping adjuster nob turn when removing the air cap. 3rd, the oil appeared to be mix of green and red (probably due to the addition of some old red Finish Line 5w oil I still have on hand). Lastly, the crown was flipped, causing the crown to contact the fork brace. This is why it was "seized" as I mentioned above. My conclusion: 15 years ago I didn't have a clue what I was doing, frelled the fork, and bought a new one.

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