Offset Bushings – must be a trade-off, reduced rear travel?

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  • Offset Bushings – must be a trade-off, reduced rear travel?
  • I’m struggling to see what’s wrong with this.

    If the holes are facing inwards, (i.e closer together than with standard bushings) when you refit the shock the linkage/swingarm will be extended slightly to match up with the holes in the shock. So the swingarm goes down, the BB is raised, and the seat and head tubes are tilted forwards slightly, making the geometry steeper.

    P.S Does this remind anyone else of the conveyor belt thread?

    Rickos
    Member

    No, no, no. If the holes are inwards they are closer to the shock, ergo shortening the eye to eye. That’s how I’d see inwards anyway.

    Premier Icon cookeaa
    Subscriber

    I think you’ve got it now…

    If you really wanted to make the effective e2e length of your shock greater then yes I suppose you could rotate them the wrong way, of course when presented with a bicycle and a couple of bits of bar with off centre holes drilled through it all becomes rather stunningly obvious though…

    If I were you I’d quit now though I’m building a rather unflattering mental picture now in which you are

    -Wearing velcro fastening shoes,
    -Need felt tip markings on either hand to indicate Left
    -Require supervision when operating a spoon,,,

    greeble
    Member

    If the holes are facing inwards, (i.e closer together than with standard bushings) when you refit the shock the linkage/swingarm will be extended slightly to match up with the holes in the shock. So the swingarm goes down, the BB is raised, and the seat and head tubes are tilted forwards slightly, making the geometry steeper.

    slacker you have it the wrong way round

    Cookeaa – you’re very funny, and accurate on at least one of those points. But I think I have found some similiarly befuddled friends on this thread.

    I think the second penny may have now dropped though, as you say, when the lumps of metal turn up it will all be clear no doubt.

    greeble
    Member

    3. Take your new, offset bushings and slot them in. Make sure the hole is facing the inwards if you wish to slacken the bike , outwards to steepen it.

    thats not described wrong at all

    xiphon
    Member

    3 – hole inwards = shorter distance between the shock mounts (each end) when bolted to the shock. The i2i of the shock doesn’t change, nor does the stroke length. Travel remains *exactly* the same as before..

    Therefore it slackens out the head angle…

    clubber
    Member

    OK, who’s going to draw it to explain to those who haven’t got it yet πŸ˜€ – really this is very simple πŸ™‚

    Premier Icon porter_jamie
    Subscriber


    Sorry, my handwriting is shocking.

    Excellent, despite being a proven idiot, I have just created my longest ever STW thread and so far learnt very little (other than about Cookea’s lack of culinary skills and that velcro is for simpletons).

    slacker you have it the wrong way round

    Thanks, I started drawing a picture and you are correct.

    I was imagining inward meant the hole was moving towards the shock, when in fact the hole is the fixed point (obviously) and the bushing itself is actually moving out.

    So holes inward is slacker, agreed πŸ™‚

    alex222
    Member

    A and B are correct C would not happen the bushes will always tend to the shorter position shortening the effective i2i of the shock. The trade off compared to angle reducer cups which only slacken the head angle; is that the head angle is slackened as well as the bottom bracket lowered.

    I was imagining inward meant the hole was moving towards the shock, when in fact the hole is the fixed point (obviously) and the bushing itself is actually moving out.

    Thanks, this was the concept I’ve been struggling with (ie. which point is fixed).

    greeble
    Member

    seriously it took two pages and a diagram to understand that?
    😯

    no wonder it takes meetings that span days and power point presentations on how to ring fence a unicorn.

    you guys are seriously lacking in the brain cell department

    tracknicko
    Member

    yeh im with spooky. stupid fixed holes not fixing holes.

    Premier Icon cynic-al
    Subscriber

    *points and laughs* πŸ˜€

    Premier Icon Northwind
    Subscriber

    This thread is full of confusion, it’s great.

    One of the tradeoffs you have to take into account is that the minimum eye-to-eye is now shorter than before, so when bottomed out the shock is shorter than it was when bottomed out before. On some designs, there’s enough clearance for this to work, on other designs hard parts will collide. My Ellsworth has tons of room to maneuvre, my Hemlock almost none. This should be obvious tbh but it almost never gets mentioned.

    Premier Icon cynic-al
    Subscriber

    We were just focussing on laughing at people.

    toys19
    Member

    spooky you were right, porter jamies drawing is wrong.

    Premier Icon cynic-al
    Subscriber

    No, he’s wrong.

    Premier Icon porter_jamie
    Subscriber

    Seriously, i dont understand what the confusion is. Its very simple isnt it?

    toys19
    Member

    It is simple, but you have reversed it..
    Edit unless I have misunderstood your drawing. Are the holes in your drawing concentric with the shock eyes holes or the frame holes?

    Premier Icon vinnyeh
    Subscriber

    This thread is full of confusion, it’s great.

    One of the tradeoffs you have to take into account is that the minimum eye-to-eye is now shorter than before, so when bottomed out the shock is shorter than it was when bottomed out before.

    Are you just adding to the confusion for the hell of it? πŸ™‚

    Premier Icon Northwind
    Subscriber

    Seems clear enough to me…

    toys19
    Member

    Doh its obvious they are concentric with frame holes, you are right porterjamie, and I’m a dummy.

    The holes are the frame mounting holes, the shock is still effectively fixed to the +’s.

    toys19
    Member

    thanks spooky. I see it now, was being king of the thickos there for a minute.

    pdw
    Member

    The picture would be clearer if you aligned the little circles rather than the big ones, because the shock length doesn’t change. It then becomes (even more bleedingly) obvious what happens to the rest of the bike.

    toys19
    Member

    The picture would be clearer if you aligned the big circles rather than the little ones, because the shock length doesn’t change. It then becomes (even more bleedingly) obvious what happens to the rest of the bike.

    This was going to be my complaint but after a bit of consideration he has the drawing bang on, if you moved the big circles then it would be wrong. What might improve it are some lugs around the mounting holes to show the frame components moving closer together in B and further apart in C

    pdw
    Member

    The picture would be clearer if you aligned the big circles rather than the little ones

    Impressive – you managed to quote my original version in the 5 seconds between posting it and changing it πŸ˜€

    But you’re right – big holes are attached to the shock, little holes to the frame. Some lugs would make it clear.

    Premier Icon porter_jamie
    Subscriber

    Chaps, i made several assumptions with the sketch.
    The shock has big holes in which the bushes fit.
    The shock actual i2i does not ever change unless you buy another shock.
    The frame has small holes which the bolts go through.
    The effective i2i reduces because of the offset
    The effectively reduced i2i lowers the rear of the bike
    This slackens the ha.
    Comment earlier re slacksets, or offset headsets which slacken the ha not reducing bb height is wrong.
    Slacken the ha using slackset and change nothing else, the bb HAS to get lower.

    Rorschach
    Member

    I LOVE THIS THREAD πŸ˜€

    Premier Icon cynic-al
    Subscriber

    Is there a way of making it shorter?

    Premier Icon porter_jamie
    Subscriber

    It’s full of eccentrics

    I’m terribly sorry, coat etc…

    when bottomed out the shock is shorter than it was when bottomed out before

    unless it the frame bottoms out on itself first.

    no matter how much of a he-man you are I very much doubt you’ll be able to do up your frame bolts enough to clamp the eccentric bushings hard enough to keep the shock in postion “c” so realistically they’re not much good to steepen your head angle. You could always get longer shock and then fit offset bushings though.

    toys19
    Member

    oliver1981, I’m would not be so sure, there are lots of bridges held together by preload induced friction grip, ever heard of hsfg?

    alex222
    Member

    oliver1981, I’m would not be so sure, there are lots of bridges held together by preload induced friction grip, ever heard of hsfg?

    Is this not a bush though? A component designed to reduce friction?

    toys19
    Member

    Ah yes, sorry didn’t mean to be so confusing, I an talking about the friction between the end of the mount pin and the face of the mounting lug it is compressed up against. Not the same surface as the bushing surface. The bolt goes through the mount pin and squashes it between the lugs.

    The concept of the mount pin and lug relies on friction to stop any movement of the mount pin between the lugs, it is a common misconecption that the mount pin acts in shear/bending on the mounting bolt

    greeble
    Member

    some people are thick as shit

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