I obtained a second hand Schwinn Runabout Child's bike that attaches to the seat post of my bike with the pictured example of the attachment.

However I am missing the three rings to use for a secure fit. Any idea where I could get something like this? My online search came up empty, unless I want to purchase a whole new attachment.

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  • 2
    I'd be tempted to try a piece of inner tube wrapped around the post a couple of times. Commented Apr 27, 2020 at 1:38
  • Original related question (not a dupe) bicycles.stackexchange.com/questions/45075/…
    – Criggie
    Commented Apr 27, 2020 at 4:44
  • Or even just a few sticks of wood.
    – Michael
    Commented Apr 27, 2020 at 5:49
  • 1
    They resemble seat post shims. what size is the outer diameter of the seat post and the inner diameter of the attachment clamp?
    – Swifty
    Commented Apr 27, 2020 at 8:28

1 Answer 1


You need a seatpost shim, with an inner diameter that matches your existing seatpost, and an outer diameter that matches the inner diameter of the clamp. Any decent bike shop will have these.

The measurement of your seatpost should be stamped into the metal - just pull the seatpost out, and it will be written below the minimum-insert line.

There is a shim for every combination of sizes - and you can get them in plastic or aluminium or steel or carbon fibre. For your situation, a plastic shim would probably be fine, but I'd still prefer a metal one.

Examples (not a recommendation) https://hollandbikeshop.com/en-gb/bicycle-saddles-seatposts/seatpost-shim/

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