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  1. #1
    Te mortuo heres tibi sim?
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    Dropping travel while preserving geometry...

    My current squishy bike ride has not quite 6.5" in back, and a 7" travel front. It's slack. I like it. But, I really don't need that much travel, I just really like the slackness.

    Thoughts: Drop to a shorter i2i and stroke shock, and drop my fork travel and height down 20mm as well ought to preserve similar geometry without dropping my BB too low, or shortening my wheelbase too much. (it's a single pivot frame)

    8.5" x 2.5" shock. Thinking of going to a 7.875" x 2.25" shock. I've got to measure (and am going to do so before buying the shorter shock) things a bit to ensure I won't have frame/frame/tire contact with full compression with that difference in i2i. An 8.25" x 2.25" shock would be nice if someone made one! There'd be no worries on contact that way!

    Yes, the BB will drop. It's already a bit on the high side, which I'm fine with. I'll be running less overall sag front and rear as well, so things ought not be too low hopefully.

    Thoughts? Anything big I'm missing? Again, this is all dependent on if the shorter shock will work without frame and tire contact on the seat tube at full compression.
    Florence Nightingale's Stormtrooper

  2. #2
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    i dunno man, you're gonna make for a pretty poor pedalling bike, i think, by lowering it. Chain tension won't be able to combat the suspension compressing. If you're gonna do it, why not just get a smaller air can and run less pressure?
    .

  3. #3
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    Quote Originally Posted by scottzg
    i dunno man, you're gonna make for a pretty poor pedalling bike, i think, by lowering it. Chain tension won't be able to combat the suspension compressing. If you're gonna do it, why not just get a smaller air can and run less pressure?
    people have been doing similar with old heckler and bullit frames for years without much trouble. again, so long as things clear tire and frame wise.

    i'm not at all getting how you think a smaller air can and lower pressure will get me the difference i'm looking for.

    i like the bike as is, and am not looking for better pedaling, different suspension performance. just experimenting with winter heading my way. lower, shorter with the same overall head angle and slightly less travel? if i can get things to clear, i'll try it. don't think it'll pedal like ass, IMO.

    if it works like crap, i sell off the shorter shock and haven't really lost much by trying.
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  4. #4
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    A 2/3" drop will slack the bike a lot. And lower it a lot. I am not sure how much but maybe 2 deg. I am just guessing but I am basing this guess due to the fact that my Giant faith can be made slacker by flipping the rear suspension links. This equates to a shorter i2i of about a 3/8th of an inch but slacks the bike by at least a degree.

    But lowering the front 20mm would give you back 1 degree.
    I am concerned that your BB will lower almost a whole inch.

    Try it though. It's fun to experiment.
    And let us know what the actual measurements are.

    It's too bad the Heckler didn't use a 8.75 x 2.5" shock like my 6point. I can go to 8.75 x 2.75 for more travel or 8.5" x 2.5" for lower and slacker.
    Also I have a internal headtube on the 6point. I can add a 15mm external cup or a Betd adapter(with external cup) to increase stack height. It's another way to change geometry.

  5. #5
    Te mortuo heres tibi sim?
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    Quote Originally Posted by wormvine
    A 2/3" drop will slack the bike a lot. And lower it a lot. I am not sure how much but maybe 2 deg. I am just guessing but I am basing this guess due to the fact that my Giant faith can be made slacker by flipping the rear suspension links. This equates to a shorter i2i of about a 3/8th of an inch but slacks the bike by at least a degree.

    But lowering the front 20mm would give you back 1 degree.
    I am concerned that your BB will lower almost a whole inch.

    Try it though. It's fun to experiment.
    And let us know what the actual measurements are.

    It's too bad the Heckler didn't use a 8.75 x 2.5" shock like my 6point. I can go to 8.75 x 2.75 for more travel or 8.5" x 2.5" for lower and slacker.
    Also I have a internal headtube on the 6point. I can add a 15mm external cup or a Betd adapter(with external cup) to increase stack height. It's another way to change geometry.
    Assuming the shock can work without getting me tire rub, the BB hieght possibly being too low is the only thing that would be a deal breaker. All the other changes are things I like. And the bike shouldn't alter it's head angle much, so long as I run the fork dropped 20mm.

    Will have to pedal it around and see. Too many pedal strikes, or too many that I don't accomodate my pedaling style around will kill it.
    Florence Nightingale's Stormtrooper

  6. #6
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    Quote Originally Posted by scrublover
    Assuming the shock can work without getting me tire rub, the BB hieght possibly being too low is the only thing that would be a deal breaker. All the other changes are things I like. And the bike shouldn't alter it's head angle much, so long as I run the fork dropped 20mm.

    Will have to pedal it around and see. Too many pedal strikes, or too many that I don't accomodate my pedaling style around will kill it.
    Well let us know how it goes.

  7. #7
    squish is good
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    Yeah, I like your thought process, give it a shot and let us know. Not too many seem willing to try different shock setups on modern frames these days.
    Bike good, work bad.

  8. #8
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    Quote Originally Posted by Clutchman83
    Yeah, I like your thought process, give it a shot and let us know. Not too many seem willing to try different shock setups on modern frames these days.
    i can see funky things happening more with multi pivot, linkaged and so on bikes more than i can with a simple single pivot.

    if things measure decently, i can have a shorter shock on and get some ride time in in the next couple weeks to see how it feels.
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  9. #9
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    Quote Originally Posted by scrublover
    i'm not at all getting how you think a smaller air can and lower pressure will get me the difference i'm looking for.
    you'd get more sag and more spring ramp up. or maybe not, i'm no FS guru, i just know that riding around with the suspension lowered so the chain torque doesn't stiffen the suspension feels pretty awful.
    .

  10. #10
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    Quote Originally Posted by scottzg
    you'd get more sag and more spring ramp up. or maybe not, i'm no FS guru, i just know that riding around with the suspension lowered so the chain torque doesn't stiffen the suspension feels pretty awful.
    On a single pivot the more the suspension compresses the more chain torque will stiffen the rear end. I'd wager that the pedaling characteristics will be just as good if not better in a lowered condition.
    Bike good, work bad.

  11. #11
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    Quote Originally Posted by scrublover
    8.5" x 2.5" shock. Thinking of going to a 7.875" x 2.25" shock. I've got to measure (and am going to do so before buying the shorter shock) things a bit to ensure I won't have frame/frame/tire contact with full compression with that difference in i2i. An 8.25" x 2.25" shock would be nice if someone made one! There'd be no worries on contact that way!
    What shock do you have at the moment? Buy the same one but in 7.875x2.25 and try it out on your bike. If it's too low or it rubs, tear both shocks down and switch shafts to get a 8.25x2.25. Assuming you currently have a coilover of course.

  12. #12
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    Quote Originally Posted by Clutchman83
    On a single pivot the more the suspension compresses the more chain torque will stiffen the rear end. I'd wager that the pedaling characteristics will be just as good if not better in a lowered condition.
    Agreed. I'm not addressing that point in his posts because I'm really not expecting much change in how the bike pedals. At least not anything I'll be able to really notice.
    Florence Nightingale's Stormtrooper

  13. #13
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    Quote Originally Posted by Clutchman83
    On a single pivot the more the suspension compresses the more chain torque will stiffen the rear end. I'd wager that the pedaling characteristics will be just as good if not better in a lowered condition.
    hmm, my impression was that as soon as the chainline was aiming below the pivot the chain worked to compress the suspension.
    .

  14. #14
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    Quote Originally Posted by scrublover
    Agreed. I'm not addressing that point in his posts because I'm really not expecting much change in how the bike pedals. At least not anything I'll be able to really notice.
    So what exactly are you hoping to gain? You want the same geometry, and don't expect the pedal performance to change, so what is the point? The rear shock won't really weigh much less, and if you have an adjustable travel fork the weight will be the same. You said you'll run less sag, so that will put you up a bit higher, negating any lowering of your center of gravity, and will give you a harsher ride.

    I completely understand wanting to have a short travel bike with relaxed geometry, even though those are few and far between. However, turning a long travel bike into a shorter travel bike doesn't seem like it will accomplish much other than as part of an economic stimulus plan.

  15. #15
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    Quote Originally Posted by rmccully
    So what exactly are you hoping to gain? You want the same geometry, and don't expect the pedal performance to change, so what is the point? The rear shock won't really weigh much less, and if you have an adjustable travel fork the weight will be the same. You said you'll run less sag, so that will put you up a bit higher, negating any lowering of your center of gravity, and will give you a harsher ride.

    I completely understand wanting to have a short travel bike with relaxed geometry, even though those are few and far between. However, turning a long travel bike into a shorter travel bike doesn't seem like it will accomplish much other than as part of an economic stimulus plan.

    I'll second that opinion. Why?

  16. #16
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    Quote Originally Posted by tmarkos
    I'll second that opinion. Why?
    Uh, because I can? I like the bike as is. Nothing is wrong with it. The idea of the same geometry with a bit shorter wheelbase and stays is the main appeal, and just that I don't really need that much travel. The whole thing is more to see how it rides, with an eye towards my next bike down the road.

    Again, it's not set. Only going to try it if the measurements look like it won't get me tire rub, or drop the BB too low. Fedex will be dropping my bike off from my recent Moab trip tomorrow, and then I can measure things and run some numbers.

    Yeah, if money was no object I'd custom build a new ride in the 5-6 travel range with the same slackness. Me likey my 66* head angle.
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  17. #17
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    Don't get me wrong, I'm all for tinkering and customizing a bike to your liking. From your first post, it wasn't clear to me what you aimed to accomplish. I get it now , and that seems like a perfectly good reason.

  18. #18
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    I've been thinking about doing the same thing with my Bullit for the same reasons and basically the same trails You are..
    The only thing I'm worried about is the lower BB.
    Let us know how it goes.

    BTW: I remember a while back you were thinking about making some kind of shock shuttle similar to a Bullit to alter the geometry..
    Did you ever go through with it.

  19. #19
    Te mortuo heres tibi sim?
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    Quote Originally Posted by mcrumble69
    I've been thinking about doing the same thing with my Bullit for the same reasons and basically the same trails You are..
    The only thing I'm worried about is the lower BB.
    Let us know how it goes.

    will do. assuming the shock will fit, bb height would be the only real deal breaker.


    BTW: I remember a while back you were thinking about making some kind of shock shuttle similar to a Bullit to alter the geometry..
    Did you ever go through with it.
    nah. to do that and make it work, i'd have to drill another hole in my front frame shock mount area- i wouldn't trust the shuttle to be stable with only one bolt holding it in - it would end up rotating around that bolt. for that hassle, if i do that, i can just drill one and mount the shock direct instead of using the shuttle. same thickness throughout the whole mount area. only thinking of this though if the shorter shock drops the bb too low.

    don't think i really want to do that though. very careful measurements to be done if i decide to go that route though. probably drill it just enough back to end up effectively giving the shorter shock a position that would be equivelant to a 8.25" i2i shock. 0.375" back form the main mount. if there is enough room.
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  20. #20
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    You need a Preston.

  21. #21
    Te mortuo heres tibi sim?
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    Quote Originally Posted by singletrack
    You need a Preston.
    heh. been there, done that.
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