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  1. #1
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    2006 Rush rear shock relacement options

    So, my rear shock on my 2006 Rush is starting to die. Already been rebuilt once and it just seems to be losing air in every ride now (about a year later). During the rebuilt the shop found a scratch on the stanchion which seems to leak a small bit every time the shock gets compressed that far into the stroke.
    Looking at possibly upgrading. Contacted local Cannondale dealer for options and the called Cannondale and Fox. since the shock was proprietary, neither company has any left and both basically suggested ebay.
    I'm just wondering what my other options may be? Shorter 100mm travel? Move up to 120mm of travel? I'd like to get another Fox shock.
    I'm not overly wise on my shock options these days. Any help would be greatly appreciated.

  2. #2
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    Are you sure that isn't just a standard length shock

  3. #3
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    Where is the scratch? The air seal is inside the shock outside is just a wiper seal.....if you have a scratch on the outside where you measure the stroke and such it's not going to cause any air leaks....
    I'm using a "Standard" 190mm (7.5") shock and it works without any issues, checked without air in the shock and fully compressing it...no clearance issues what so ever.....
    "Common sense isn't always that common!"
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  4. #4
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    fox should be able to supply a new shock body, i had the job done by mojo - fox warranty (in the uk) last month. the part cost 30 on top of the cost of a complete rebuild. i doubt very much that it was the last rush specific shock body in the world!

  5. #5
    2OFME
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    Quote Originally Posted by ccaddy View Post
    Are you sure that isn't just a standard length shock
    Yes. The eye to eye is 7.5" but the stroke length is different. Both fox and cannondale said they have no more shocks left in stock. I trust the shop I talked with very much.
    The standard 7.5" x 2.0 by my understanding is longer than the original which I think the shop told me was 1.75. That is what I am looking for, any information on if the 2.0 will work.

    The scratch is inside the body of the shock, not on the outside. The dust seal popped out and it took me a few months of riding to bring it in for a new seal kit and overhaul. Best guess estimate by the guys at the shop is something got behind the dust seal and caused a nice 1/2" scratch in the shock.

  6. #6
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    I just talked to C'dale and they said they have close to 100 Rush shocks available.
    KF371 is the part # for the RP23 for the Rush.

  7. #7
    2OFME
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    Thank you. I am going to have to call and harass my local shop....these guys have never steered me wrong before........

  8. #8
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    Quote Originally Posted by onrhodes View Post
    Yes. The eye to eye is 7.5" but the stroke length is different. Both fox and cannondale said they have no more shocks left in stock. I trust the shop I talked with very much.
    The standard 7.5" x 2.0 by my understanding is longer than the original which I think the shop told me was 1.75. That is what I am looking for, any information on if the 2.0 will work.

    The scratch is inside the body of the shock, not on the outside. The dust seal popped out and it took me a few months of riding to bring it in for a new seal kit and overhaul. Best guess estimate by the guys at the shop is something got behind the dust seal and caused a nice 1/2" scratch in the shock.
    I have a 190mm (7.5) shock with a 2" stroke on my Rush SL (with the support brace on the swing arm) and there are zero (0) issues.
    You can always reduce a 2" stroke shock to 1.75" by unscrewing the air canister and placing an additional .25" bottom out bumper on the shaft.
    "Common sense isn't always that common!"
    Custom Prophet and Custom Delta V

  9. #9
    2OFME
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    I've gotten so much contradictory information in the past week it is not even funny. I have one cannondale dealer telling me the shock is not made anymore for the 2006 Rush, can't be found and nobody has any in stock. Plus the rear shock is proprietary.
    I have another local cannondale dealer telling me I can easily use a 7.5 x 2.0 shock and that they have to order them through Fox and that the cannondale part # I gave them means nothing.
    I have a poster here saying he called cannondale and they have close to 100 shocks available and posted a cannondale part #.
    I even called cannondale myself yesterday and left a message with the inside tech rep, and of course he has not called me back.

  10. #10
    2OFME
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    "Official" word from Cannondale
    Thank you for choosing our Rush. Here are the answers to your questions:

    1. Is the shock proprietary and I need a cannondale specific 7.5 x ??

    **The Rush requires a rear shock with a 7.5 inch eye-to-eye with a 1.75 inch stroke.

    2. Can I use a standard 7.5 x 2.0 Fox RP23.

    **We only recommened what we require.

    We still have rear shocks available for our Rush Carbon, item number KF371/. We no
    longer have for our alloy models. Two companies that may be of assistance:
    www.risseracing.com and www.pushindustries.com.

    Your local Cannondale Retailer can further assist.

    Thank you for contacting Cannondale. Have a nice day.

  11. #11
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    A side by side picture comparison of a 1.75" and a 2" shock would be nice...anyone ?
    It's like a car dealer saying only to use oem rims but aftermarket will fit just as well...if you're the original owner of the bike it might be a good idea to order a new shock through cannondale so you don't void your warranty...other than that I really don't see any problems here....I have a Large frame BTW so maybe a 2" stroke might be a concern on a M, S or XS frame.....
    "Common sense isn't always that common!"
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    I am also using a 7.5" x 2.0" RP23 with no problems on a large 2008 Rush with the swingarm brace. I'm pretty sure the only difference between the Rush alloy and Rush carbon shock is that the shock mount to the top tube of the carbon Rush is 28.8mm and the alloy Rush is 32.5mm. You just have to change the mounting hardware where it attaches to the top tube. The mount to the swingarm is the same at 37.5mm.

  13. #13
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    I also have a 2006 AL rush and I hope the 2.0 will fit. Let know what's u going to do about this, my rear shox is in its last days too

  14. #14
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    Here is the deal. My local Concord, NH Cannondale dealer is stupid. The kid I talked to said a 2.0 will work just fine and that he was going to order me a shock direct from Fox for $330. I called Rhino Bike Works in Plymouth, NH and had them quote me on the Cannondale part # which is the 1.75" stroke that came on the Rush. They came back with a $289 price quote.
    Needless to say I went with the Cannondale supplied part. Rhino said that using a 2.0 would probably work, may mess with the geometry just a tad, but more importantly would basically void any warranty on the frame should somthing happen. That was all I needed to hear to stick with the Cannondale supplied part.
    I'm sure the 1/4" difference in stroke would have worked, but when the cannondale email and a shop I trust both say go with the stock part (and it is significantly less expensive) that was a total no brainer.
    I installed the shock in about 10 minutes this weekend and will be testing it out tomorrow night. It was nice to go from a Float R to an RP23.

  15. #15
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    Any recommendation on a replacement rear shock with lockout?

  16. #16
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    Quote Originally Posted by onrhodes View Post
    So, my rear shock on my 2006 Rush is starting to die. Already been rebuilt once and it just seems to be losing air in every ride now (about a year later). During the rebuilt the shop found a scratch on the stanchion which seems to leak a small bit every time the shock gets compressed that far into the stroke.
    Looking at possibly upgrading. Contacted local Cannondale dealer for options and the called Cannondale and Fox. since the shock was proprietary, neither company has any left and both basically suggested ebay.
    I'm just wondering what my other options may be? Shorter 100mm travel? Move up to 120mm of travel? I'd like to get another Fox shock.
    I'm not overly wise on my shock options these days. Any help would be greatly appreciated.
    Was kinda in your position, the specs list the rush shocks to have a 7.5" i2i and 1.75" stroke. I have a 09 rush 1 carbon and was thinking about replacing the Rp23 with a monarch rt3 but all the ones for sale are with a 2" stroke, so would that be ok? so you did end up getting a 2" stroke replacement shock? any problems? would like to know

  17. #17
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    Also quick noob question is the terms shock travel and stroke the same?

  18. #18
    2OFME
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    I went with the Cannondale part which is 1.75". The owner of Rhino Bike Works in Plymouth, NH said that moer than likely the 2.0" would work, but then said it would probably void any warranty on the frame since you were now "modifying" the bike from it's original spec'd 1.75" stroke.
    It sounds silly, but I tend to agree with him. It was also almost $50 cheaper to go with the Cannondale supplied part as opposed to a Fox 2.0" shock.

  19. #19
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    All you have to do is to unscrew the air canister and pop in a .25" bottom out bumper on the steel shaft if you really just want 1.75" of stroke. It ain't rocket science ya' know?
    "Common sense isn't always that common!"
    Custom Prophet and Custom Delta V

  20. #20
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    Quote Originally Posted by cdalemaniac View Post
    I have a 190mm (7.5) shock with a 2" stroke on my Rush SL (with the support brace on the swing arm) and there are zero (0) issues.
    You can always reduce a 2" stroke shock to 1.75" by unscrewing the air canister and placing an additional .25" bottom out bumper on the shaft.
    ya i think I have the same frame as you and I'll probably go with a 7.5"x2" RT3. Was a lil hesitant wondering if it'll be ok

  21. #21
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    Quote Originally Posted by atonyc68 View Post
    Also quick noob question is the terms shock travel and stroke the same?
    On rear shocks yes. Some folks confuse the suspension travel with shock travel though. The suspension travel varies from bike to bike...depending on the linkage used on a frame. Not all bikes with a 7.5" shock have the same amount of rear wheel travel.
    On forks stroke and travel is different depending on how much the fork is angled...on bicycles that does not make a big difference, but on Moto x bike with like 300mm travel or more you can tell.
    Stroke is measured on the shock body or fork stanchions and refers to the total amount you can achieve upon full compression.
    "Common sense isn't always that common!"
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  22. #22
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    Quote Originally Posted by cdalemaniac View Post
    On rear shocks yes. Some folks confuse the suspension travel with shock travel though. The suspension travel varies from bike to bike...depending on the linkage used on a frame. Not all bikes with a 7.5" shock have the same amount of rear wheel travel.
    On forks stroke and travel is different depending on how much the fork is angled...on bicycles that does not make a big difference, but on Moto x bike with like 300mm travel or more you can tell.
    Stroke is measured on the shock body or fork stanchions and refers to the total amount you can achieve upon full compression.
    Thanks for the explanation!

    Ok so one more thing confuses me, so on our rush the specs say: Fox Float RP23, 100mm travel, but isn't 1.75" stroke = 44.45mm? sorry for be'n dumb here lol

  23. #23
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    Quote Originally Posted by atonyc68 View Post
    Thanks for the explanation!

    Ok so one more thing confuses me, so on our rush the specs say: Fox Float RP23, 100mm travel, but isn't 1.75" stroke = 44.45mm? sorry for be'n dumb here lol
    100mm refers to the amount of rear wheel travel.....the rear wheels maximum vertical suspension travel is 100mm, which means the leverage ratio is about 1 to 2.25. If your rear wheel moves up 2.25mm the shock uses only about 1mm of it's stroke.
    "Common sense isn't always that common!"
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  24. #24
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    Quote Originally Posted by cdalemaniac View Post
    100mm refers to the amount of rear wheel travel.....the rear wheels maximum vertical suspension travel is 100mm, which means the leverage ratio is about 1 to 2.25. If your rear wheel moves up 2.25mm the shock uses only about 1mm of it's stroke.
    ohhh i c i c thanks for clearing that up! I always thought they were just talking about the shock and not referring to rear wheel travel as they always have in the specs ie fox rp23 110mm

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