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  1. #1
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    Suspension questions

    Ok so what I am doing is building a cannondale super v 900. I am building it up to be more suitable for dh and want to get the most suspension travel out of it I can. I asked this in other parts of the forum but the only answers I get are save your money and build a different bike. If I wanted to do that I wouldn't have asked the question. But i wanted to know how to figure out how big a fork I can put on there and same for the rear shock so the bike stays in a decent geometry for dh riding. I am hoping I can get at least 160mm fork on the bike. But like I said don't know how to figure that out

  2. #2
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    As a general rule you don't want to go 20mm travel more than the bike was designed for, on some bikes 20mm may even be pushing it. Is it possible to run 160mm of travel on a super v frame? Yes. Is it safe? No. Adding a longer travel fork to a bike, will change the bb height, the head angle, the seat angle, and put stress on the frame in places that was not designed to handle the stresses.
    Aluminum ages quickly on an mtb frame, and I believe the super V is a fairly old bike, so putting the extra stress on the frame from the longer fork, and the dh style abuse your riding may end up in mayhem, carnage, and death. Which is why the recommendation is to get a different frame to start from.

  3. #3
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    You missed half the post I asked about the rear suspension as well as to keep the geometry of the whole bike. And if there was a way to measure the bike or something along those lines to figure out what the max travel could be. You only took one small piece of what I asked and based a whole answer on that one thing. You should read a whole post if your gonna reply.

  4. #4
    > /dev/null 2&>1
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    Re: Suspension questions

    You're in a no win for adapting that bike to dh.

    By raising the fork, yes, you're getting more travel in front and slackening the head angle, but at the same time you are raising the bottom bracket which will put you high on a perch and make the bike feel less stable.

    To calculate how much, you gotta pull out your high school trig - check out my post here for info on how to calculate bb increase for a given increase in front height :

    Front tyre size and bb height

    This post was about bigger tires but the principles are similar for longer forks. For big increases in fork travel (like you mentioned 160mm, which is double the 3 inches stock travel) , you'll get non trivial bb height increases. For changes in front height of this magnitude, these equations will not be perfect but it'll give you an idea. +3 inches in front could yield +1 inch or more at the bb. That's going away from a dh bottom bracket height.

    Secondly you cannot increase travel in the rear just by adding more shock travel back there, it can cause problems. A few bikes are designed for this but not this one. If you have the single carbon chainstay rear swingarm design, you'll notice that the front derailleur post is close to the swingarm and a longer shock may cause the swingarm to hit the post. Secondly, adding a longer rear shock will change the progression of the spring curve, reducing the leverage ratio in the first part of travel and probably causing harsh behavior. Thirdly the whole bike be rotated slightly forward by the more extended rear wheel, putting you in a more forward position, steepening the seat tube angle and head tube angle, which is the opposite of what you want to do for dh.

    Its best not to berate those trying to give you valid advice. Boomcars probably didn't respond to your question about raising the rear because most people know you can't go do this without turning it into a Walmart geometry and he assumed you weren't actually suggesting that so as not to insult your intelligence.

  5. #5
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    It looks like Cannondale made a super V DH with about 6" of travel, supposing you are able to find a swing arm in usable condition, and it will bolt to your frame, and the only difference between the dh and the non dh version is the swing arm you can get more travel without totally screwing up you geometry, for the amount of money you spend on the swing arm and shock, you have spent as much or more as getting a used frame designed for your intended use. But the assumptions needed to be made for this to work are not reasonable assumptions, the dh frame is a much more heavily reinforced frame to handle the stress of dh.

    If you want to see what putting a longer shock will do to your frame, get a half inch pvc pipe cut a bit longer than the length of shock you want, drill holes at the eyehole lengths for the new shock size, pull out your current shock and put the pvc pipe in, take a look at that new awesome wheel alignment, if it fits at all, and think "do I want to ride this bike?"

  6. #6
    Delirious Tuck
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    Geometry aside. What do you consider DH and would you be looking to do with this bike? Where and how would you ride it?

    If you're a good rider, maybe you want to go with the Pike or Fox 34 DJ fork, burly and capable, keep similar/same rear travel with a better shock and essentially create a Slopestyle/flow trail type mini-DH bike.

    That said, if you do that, with an old frame, don't expect longevity from the frame. Quality has improved substantially over the years so you could do this with an 08/09/10 and run it properly a couple seasons. Something old with unknown use history and already shaky reliability, might not want to be sailing 30' gaps, 15' drops, and bombing rock gardens.

  7. #7
    > /dev/null 2&>1
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    Misfit, turns out there's a whole thread on this exact topic, 50 pages long. Folks have mixed in different swingarms, had headset cups custom made to allow different forks, etc.

    Post your UBER V !!!!!!!!!!!

    But, nevertheless, problems above are still real. Good luck.

  8. #8
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    Procter thanks for the link to the post on how to measure everything out now I got to just brush up on my math skills. And yeah I was asking questions in the Uber V post and reading through everything as I got the chance to. And to answer thefriars question I dont do any crazy downhill anymore. I am getting older and my body cant handle bouncing off trees anymore lol. So I wouldnt be putting tons of stress on the bike. Most of the trails I ride are very few rocks and only like 2ft drops loose dirt and tree roots. Basically I could prob get away with min suspension for the way and what I ride Im just tryin to get that extra to help prolong some of my body parts to be able to keep riding. Plus I have to rebuild the whole bike anyway and replace the forks and shock there blown beyond repair. I had the bike givin to me its sat for years and everything is setup or just bad. Now its in my dungeon and hopefully I can give it a new lease on life and make it useful to me in the meantime

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