1. The most important thing about buying a new bike is to make sure it fits. The only way you'll know if the bike is right for you is to size up the bike and make sure that the bike's geometry matches your body's geometry. Ask questions and do some research.
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Thread: Rear Shock Size

  1. #1
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    Rear Shock Size

    Well my bike's current shock which has an eye-to-eye of [7.875 inches and a stroke of 2.75 according to LBS] [I measured 8 x 2.5-2.75] broke, now a shock of same dimentios is almost impossible to find and when I do find one the price is about half the bike. Now on my bike, a shock of 8.5 and even 9 inches will physically fit, so could I get a 8.5 x whatever to replace my current one or is it strongly not advised?
    Last edited by magixx; 07-30-2008 at 06:51 PM.

  2. #2
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    A slightly different shock is no problem. But if going from a 7.875 to an 8.5 works is a real question. The larger shock will push ther rear wheel further down and effectively steepen the angles and bring the BB height up. How much depends on the frame and how the shock is actually used within the frame.

    What shock is this and what bike? 7.875x2.75 is highly unusual.
    "Lorem ipsum dolor sit amet, consectetuer adipiscing elit." - And I agree.

  3. #3
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    This is a supposedly "Raleigh Smokin", which not even Raleigh or the whole Internet has hear of (I asked them but no reply, *******s). Here is what the bike looks like:

    Bike in Question:


    Old shock:




    Frame Close-Up






    Last edited by magixx; 07-31-2008 at 10:09 AM.

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    Are you positive it is a 2.75 stroke? From this picture, it looks to me like the stroke is only 2"... but I can't really tell what is behind the coil at either end of the shock.


    Quote Originally Posted by magixx


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    Hmm, when I remeasured it myself it could actually be 8" and not 7.875 as I could see the 0 mark in the middle of the first hole and the 8 mark in the middle of the second hole. And the stroke could be 2.5-2.75 from my measurements using THIS. Also I'm not positive on the stroke either but the LBS guy said it was 70mm which is 2.75 inch. The pic is angled so proportions are off a bit:

    Last edited by magixx; 07-30-2008 at 06:50 PM.

  6. #6
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    Quote Originally Posted by magixx
    Hmm, when I remeasured it myself it could actually be 8" and not 7.875 as I could see the 0 mark in the middle of the first hole and the 8 mark in the middle of the second hole. And the stroke could be 2.5-2.75 from my measurements using THIS. Also I'm not positive on the stroke either but the LBS guy said it was 70mm which is 2.75 inch. The pic is angled so proportions are off a bit:


    Ok, if the LBS said it was a 2.75" I won't doubt it. I just couldn't really tell if that black thing at the other end of the shock moved or not; the travel you had used was 2". Good luck finding something that will fit your bike and your budget!

  7. #7
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    Take the spring off, release the pressue. Push it together and meassure - pull it to max distance and meassure. Could be a 8.5x2.5 would fit. You'd lose a bit of travel... but should work.
    "Lorem ipsum dolor sit amet, consectetuer adipiscing elit." - And I agree.

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    Here are more pictures:




  9. #9
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    looks like 2.5"...
    Quote Originally Posted by magixx

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    Nope. That is a 2.25". The rubber thingy protects a steel/aluminium sleve that would colide with the shock body if travel would exceed 2.25".

    What I still have difficulties to see is the eye-to-eye length. It is something around 8". But I cannot see if it is more than that... There is a chance that a Fox Vanilla R 7.875x2.25 would fit. That would be a $250 at www.bikebling.com or www.universialcycles.com (plus required mounting hardware).

    But let's go step by step:

    Please confirm it is 2.25" (am I right wrt the sleve?)
    Please confirm the eye-to-eye length.

    Please double check if the frame could handle a 7.875 shock. You did a fantastic first step to that in your 2nd frame close up picture. Now all you have to do is to ensure there is no collision anywhere if the shock compresses to 5.6" (please check my math).

    Next step than is spring rate and mounting hardware.
    "Lorem ipsum dolor sit amet, consectetuer adipiscing elit." - And I agree.

  11. #11
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    Quote Originally Posted by Kaba Klaus
    Nope. That is a 2.25". The rubber thingy protects a steel/aluminium sleve that would colide with the shock body if travel would exceed 2.25".
    right you are... duh.

  12. #12
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    What if I would get and 8.5 but put a softer coil on?

  13. #13
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    Good thinking. Yes, that is indeed an option. The perfect 8.5 would have a 2.75 stroke. Through the softer spring you would use up the 0.5 as additional sag.

    Now, if you use a 8.5 with a 2.5 stroke you either change the geometry of the bike or you sacrifice travel.

    1) 8.5 is 0.5 too long. So let's assume you compensate by 0.5 additional sag... Result is your effective stroke (compared to the original shock) is only 2 or 0.25 less than before. Not sure what the result on the suspension handling etc would be.

    2) Let's assume you don't compensate through additional sag... Result is that the shock is 0.5 too long. That will effectively lift your bottom bracket and make your head tube angle a little steeper. Not sure what the effect on the bike handling would be.

    In reality the effect will be a combination of 1) and 2). You can trade one effect against the other using spring tension (preload).

    So in summary... Yes you can do that - if you did the collision test correctly and ensured that the shok will fit the frame. You just need to understand that you will not be able to get 100% to the same bike handling as before. If you are OK with that and happy to experiment: Just go for it.
    "Lorem ipsum dolor sit amet, consectetuer adipiscing elit." - And I agree.

  14. #14
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    Well shock arrived today here are some comparison pics:






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