A Tool to Quickly Measure 3:1 for Time Trial Bikes

Post date: Sep 4, 2014 11:36:30 AM

Although the new UCI sticker on TT bikes often replaces the need to measure 3:1 on TT bikes, sometimes you need to take a measurement.

Currently, you use calipers to measure the narrowest dimension, multiply by 3, then check that the widest dimension is narrower than that measurement. But, his is time consuming, error prone (doing the mental math gets tedious after a few hundred times or so), and the calipers are sharp and can scratch the expensive bikes.

I got inspired looking at a piece of leftover wallboard-square I had destroyed in a previous project.

A few saw blades and some filing later, and I came up with a way to measure 3:1 extremely simply and quickly (photo attached)..

The device is simple and consists of a short and long pivot. The short arn is 10cm, and long arm is 30cm - the gaps between the small jaws and large jaws are exactly 3:1.

Set the wide jaw with the wing-nut at the widest part of the tube/handlebar/seatpost/waterbottle.

If the narrow jaw passes over the narrowest part of the object, it is not 3:1.

You can always use calipers as backup if you need more accuracy.