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  1. #1
    CTB
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    Straight 6 - this has been bugging me

    Lots of folks here with Straight 6's (or had them) - I'm talking about the push-shock 4-Banger-style models, not the original pull shockers.

    I have a 4-Banger. The Schwinn brochures indicates that the BB height of the 4-Banger is 13.0" in stock trim. This is for a 2000 with the SID air shock. The 2001 brochure says the Straight-6 BB height is 13.2". Not much difference there.

    In the process of converting my 4B to a longer-travel shock (1.75" stroke instead of 1.5"), I've found the limit of the bike design. What I mean is this: If you remove the rear shock, the suspension will "bottom" when the rear tire crashes into the carbon upper arm. With my 1.75"-stroke shock and big tires installed, I can have this happen if I use the shorter end of my trunnion adjustment. I've heard it rub on the trail from time to time.

    So my question is this: How the hell does the Straight 6 have almost 6" of rear travel using a 2" shock stroke if the BB height is only 0.2" higher? I would think the only way to get the full 6" of travel would be to run a longer trunnion-to-eye setting, raising the bike up off the ground. Does that really only lift the BB by 0.2"? That seems to be far too little.

    Anyone have any thoughts here? Does anyone still have a Straight 6 and can measure their trunnion-to-eye distance? Thanks!

  2. #2
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    maybe schwinn used the fork's travel to it's claim of 6'' ...? you got me bro. only thing i can think of is the swing arm pivot point is alittle higher on the 6 over the 4 to get the extra travel? 4banger/stray6 tech gives me a headache lol.

    from what i was told many moons ago when the straight6 came out. you can not convert a 4banger to a straight 6 by changing the rear shock because it would change the head angle to much...? shat, i dont know, ...
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  3. #3
    CTB
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    If you have to raise the rear ride height to get the travel, then yes, it absolutely changes the head angle by a lot. Like over 1 degree steeper, which would make the bike very quick to steer.

    I used Joe's picture from the other thread (Lamparito's) to figure out that his trunnion-to-eye was about 138mm. My 4B right now is 139mm, so that didn't help clarify anything on where the extra space for the wheel travel comes from. Maybe with the dinky 1.95 tires that they used back then, you could eek out that last bit of travel before it hit the carbon arm. That's about all I can think of, as I can easily bottom out my 2.2's with just 4.6" of travel on my bike if I make the trunnion-to-eye any smaller than the 139 I have now. (That was a bit of a light bulb for me when I learned that high-volume tires (like 2.35's) aren't just wider than 1.95s, they're also a lot taller.

  4. #4
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    when my 4-banger was set up as straight 6 I never had any tire rub issues on the carbon with a 2.35 maxis on the rear. I know I'd bottom it out a lot, used to be my "freeride" bike. With the 120 mm up front and in the rear 1.5"stroke shock = 4 " =2.66:1 ; 2" stroke shock x 2.66 = 5.33", never really felt twitchy to me.

  5. #5
    CTB
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    Putting the 120mm up front helped a lot for you, Joe. I figured out that every 20mm of fork length is roughly 1 of head angle reduction, so you balanced out the bike properly.

  6. #6
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    i think the '98-'00 pull shock straight 8's had 7 or 7.5'' of travel and the '01 stay8 has 8.5
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  7. #7
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    so the way i see there is no way to convert a 4banger into straight6 without changing the geometry in a significant way... unless you put a longer front fork.
    but won't that change the total height of the bike?

  8. #8
    CTB
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    Yes, when you're not on it. Don't forget that you set your sag to a higher percent when you have more travel, so the bike sorta ends up in the same place once you're sitting on it.

  9. #9
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    unless your like me weighing in at about 130 soaking wet!! lol
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  10. #10
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    lol... i did not think about the higher sag, nice to know!

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