If anyone here is familiar with LOOK’s elastometer’s perhaps you can help me. I have been using the gray elastometer (the more cushioned one). I rode one for several months and realized a few weeks ago that it was bulging out causing the seat to lower a few mm at least. It looked like the seat post had dug up under the elastometer. I contacted LOOK and they sent me another one. This one did the same thing after only a few rides. Since the other one took months to get to that point I suspect that I am doing something wrong. The is the E post R32 but I suspect many of their posts are the same. There is a bolt in the seat that has to be tightened to 20 nM which I believe I have done though my torque wrench might not be accurate. When the seat slips like this it is very noticeable. Any ideas?
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The bolt that holds the seat to the top of the post should be separate from that which holds the post at the proper elevation.
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Can you provide a better explanation of what you mean by " the post dug under the elastomer"?
an elastomer is basically a rubber bushing if the force is not applied squarely to to the flat surface the “bushing” will have a tendency to deform. Perhaps there is a flat plate that should be on top and below the bushing. Think about how skateboards turn. They have two bushings set in cups that allow the axle to flex relative to the plane of the board. The bushings were always available in different densities.
are you a big guy? Perhaps you should try one of the harder elastomers. Remember that plastic/urothane/elastomer is more deformable at higher temperatures. Maybe it is the change in weather. When i used to use the old Onza clipless MTB elastomer pedals, I would switch elastomers for summer and winter riding…(harder for summer softer for winter).
I’m at home so I don’t have a frame handy but double check that 20 Nm torque spec that sounds way high, I recall 5 Nm.
The compression bolt is there to keep the post from popping out when you inevitably lift your bike by the saddle, it is not there to support your weight. Your weight is just supported on the elastomer.
Valid comment about your weight. The elastomer is just a vibration isolator. The purpose is to drive the stiffness low so that it essentially acts as a low pass filter (i.e., high frequency content is not transmitted). The problem is if you make the isolator too soft, it deforms too much under static load (i.e., your weight). Too stiff and it transmits all the frequency content you may be trying to attenuate.
Typically isolators are designed based on the mass of the object and the load environment (where in the frequency domain you want to isolate). Given the variety of road surfaces (the load environment side) and weights of riders (mass), sounds like this seat post is a misguided effort. Good in principle, but really hard to perfect for the masses. Aka, marketing hype. It may work for a variety of people, just depends on where Look settled on its design space. But if you are outside that design space, you won’t get the intended results.
This says 20 is about right, although I agree that it seems high.
That black thing above the elastomer and the carbon is the plate that I was discussing before.
OP does yours look like that?
22Nm is for the bolt clamping the saddle rails - not the compression plug on the elastomer. The compression bolt faces up and is on the front side of the post in a little groove. Maybe that is the source of the problem here.
I understand, and agree which is why i suggested a better description in the first place.
It sounds like the OP was talking about the bolt shown above “bolt in seat”.
And if he cranked the one you are talking about up to 20 NM then he probably has a more serious issue.
I think most seat post bolts are around 10Nm.
Just got to the office, the compression bolt is in fact 5 Nm. I’m just amazed my memory was functioning…
Mine looks the same except I have 2 small spacers below the elastometer (my seat wasn’t cut as perfect as it should have been). One thing I just noticed is that one of the spacers cracked from the compression but that is only exacerbating the problem that already existed. I’m going to tri one of the harder elastometers.
E-Post R32 has a bolt that needs to be tightened to 5 Nm that holds the post into the frame, and one that holds the seat level that needs to be tightened to 10 Nm. Not sure what you’re tightening to 20 Nm but that could be part of the problem.
The spacers you inserted between the seatpost and elastomer could be moving and “work” the elastomer in a different way than the seat tube.
Measure trice, cut once.
You might see if someone can level the surface (if it is not) that the spacers/ elastomer is sitting on. Differential stress won’t help matters.