Is it OK to use seatpost shim?

Are Seatpost Shims Safe? Seatposts have a minimum insertion length which protects the seatpost and the frame from cracks. If the shim is as long or longer than the minimum insertion length required by the seatpost, it will work just fine.

What is the most common seatpost diameter?

27.2mm
The most common diameter is probably 27.2mm, but other sizes between 21.15 and 35mm are often found, as well. Seatposts also vary in length. A shorter seatpost will typically be lighter in weight but less adjustable.

What diameter seatpost do I need?

While there are any number of post diameters out there, most modern road and MTB bike frames accept a seatpost of either 27.2mm in diameter (‘standard’), 30.9 or 31.6mm (‘oversize’). You can use a shim to enable a 27.2mm seatpost fit into a frame taking a larger standard, but not vice-versa for obvious reasons.

How do I measure seatpost size?

You can easily measure the size of the post using a digital caliper and the metric calipers to check the diameter of the existing seat post. First, if you have an old saddle-post that attaches firmly, then you can measure its outer diameter for an accurate estimate of what you need to buy.

What size seat clamp do I need for a 28.6 seatpost?

Note: The seat clamp diameter needs to match the diameter of your seat tube rather than your seatpost, which is a little smaller. For example, a 27.2mm seatpost (a size commonly found on road bikes) fits inside a 28.6mm diameter seat tube, so it’s a 28.6mm clamp you need.

How do you shim a one up dropper?

SHIM INSTRUCTIONS:

  1. Unscrew the post collar by hand and slide it up towards the seatpost head.
  2. Drop your saddle to a mid stroke position at least 75mm below full extension.
  3. Lower the upper bushing and ensure you can push it fully into the lower tube by hand (if you can’t you may need to drop the seat a bit more).