I have 3 bikes (2 mtb 1road) all with different seat post diameters. Has anyone used shims. I have 1 favorite saddle. I can buy 2 shims for the fraction of the cost of new saddles. Just switch seat and post in seconds. Quick angle adjust when needed. Am conscerned about post or frame damage. Will go from 27.2 to 31.6 and 30.9. Can only ride one bike at a time!!

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    I can't give you long-term data for usage of a shim, only used one for a short amount of time and never while constantly swapping saddles. But a few things to check first: Do all bikes have the same seatpost angle? Would you need to adust the saddle forwards or backwards when switching between the bikes?
    – linac
    Oct 28, 2019 at 13:22
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    Another thing to consider is that you may want to be able to mark the post to indicate the saddle height for each bike. The amount of post you need to insert into the frame very likely differs. Repeatedly inserting the post might wear off the lower marks. I know I would want the saddle at the same height on each bike.
    – Weiwen Ng
    Oct 28, 2019 at 15:06
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    Note also that my preferred saddle for my road bike is not the same as the best saddle for my commuter bike!
    – DavidW
    Oct 28, 2019 at 17:11
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    I managed to find the same saddle on special several times, so most of my bikes have the same or similar saddle. Keep your eyes open.
    – Criggie
    Oct 28, 2019 at 20:45
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    I have 1 favorite saddle. If that one saddle is this much of a favorite, what are you going to do when you have to replace it? Saddles don't last forever - the covering wears out, the saddle itself starts to sag, hit a big bump just wrong and have one or both rails break (and you will not be able to ride that bike home...). Is your favorite saddle still going to be available? As @Criggie implied - get some "preinstalled spares" now. It's also a lot easier then playing musical saddles. Oct 29, 2019 at 9:58

1 Answer 1


The shim will not damage either your frame or seatpost if it is of decent quality in my experience. Look for shims with a small lip at the top to ensure that the shim does not slide down into the frame. Use a "safe" lube on both the inside and outside of shim to prevent seizing.

I'm not sure how much of this is in my head or reality, but I seem to have to pay more attention to keeping the seat post bolt fastener "tight" when I use a shim.

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    Should also ensure the shim is at least as long as the frames minimum insert - especially for carbon frames ( typically 100mm). Many shims are too short. Also shim use will void warranty with most frame manufacturers, which may or may not be a concern for you.
    – mattnz
    Oct 28, 2019 at 20:28

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