Can I run a 152mm (6") shock on a 140mm (5.5") fra

Mountain bike trails & Mountain bike reviews Protected: Forums Mountain Bike Forum Can I run a 152mm (6") shock on a 140mm (5.5") fra

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    • #77850

      I have a cannondale prophet, and it a 5.5" shock but there is a little space behind the bottom mount. The 6" shock is a couple mm short of being .5 inches longer than the 5.5". The 5.5’s are hard to find.

    • #77851

      Listen to Mongoose if you change damper size not only will it effect the travel but will change the way the bike rides. It will as Mongoose says apply undue force on the pivots as well as cause damage down the road..

    • #77852

      My question was not written very clearly, i was on the phone while typing.

      I’m really just wondering if it would hurt anything to put a longer travel shock in than what came on the bike. Even if it doesn’t line up eye to eye I could just compress the shock a couple mm’s and bolt it in. The only problem would be that the shock would never get a full extension but I do not see how that would harm anything, but correct me if Im wrong.

    • #77853

      What would happen on most bikes is that when you unload the bike the damper will force it self open and may over extend the suspension and perhaps cause a pivot or which ever part of the suspension to hit something else like a stop or control arm…

    • #77854


      First, the best answer to this type of question is to contact the frame manufacturer. Personally, I am bit confused by the question. When referencing rear suspension, there is no such thing as a 6 inch travel shock. Rear shocks come in measurements like 190×54 or 8.5×2.5. The first being in millimeters the second in inches. The first number, 190 or 8.5, is the eye to eye. The second is the stroke. Generically, we use the formula, stroke x leverage ratio = travel, for lots of things with regard to suspension.

      So, if your question is, "can I put a shock with same eye-to-eye, but a different stroke on my frame?" Then, the answer is, "yes, but contact your frame manufacturer to be sure." If your question is, "can I put a shock with a different eye-to-eye in my frame?" Then the answer is, "it depends on the frame, you should contact your frame manufacturer for specifics."

      Simply sagging the shock more isn’t a good idea. One, the harsh "top outs" that Element mentions. Two has to do with compression damping. Compression damping is commonly handled one of two ways. Many air sprung shocks rely on the progressive rate of the air spring to handle compression damping. If you remove air from the shock to increase the sag, you will also increase the frequency which your frame "bottoms out." Most commonly, shocks use an oil based damping systems. As you force oil through ports, chambers or whatever, your shock will start to stiffen. When over sagged you start with greater oil volume in the chambers and get more harsh ride. When you correct for the more harsh performance, you will increase the frequency of your "bottom outs." Also the position of the chambers affects it performance. So, when you over sag, defacto you change the position of the chambers.

      Really you’re looking for a simple answer to a very complex question and the people best qualified to answer that question are the guys that designed the frame.

    • #77855

      Thanks for all the help. The question was not written well, i meant that my frame has 5.5" of travel. The shock was supposed to be a 7.875 x 2.0, but I found a great deal on a longer eye to eye x 2.0, and on a 7.875 x 2.25. Unfortunately neither is the right size. I think Im going to try the one with the longer stroke because my frame, cannondale prophet, has 2 shock mount positions and through some measurements i have determined it will work in one of them. Thanks again

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