Review on 🚲 CYSKY Seatpost Adapter Shim - Bicycle Seatpost Tube Adapter for Mountain Bike, Road Bike, MTB, BMX, Fixie Gear - 25.4/27.2/30.8/31.6/33.9/34.9 Sizes by Jabari Campbell

Installs easily in seconds as you would expect and works great on my grandson's bike. I was a little unsure if my measurements were accurate, even with a digital micrometer, but apparently they were accurate. I have to wonder if the negative comments were measured correctly and/or the seatpost or frame mounting hole was a bit off from industry standards. However, they don't mention if a competitor's product worked better for them, so the question is whether this product was the wrong solution to their setup problems.