Stem Removal and Installation: Threadless

1

Begin

What tools do I need?

Tape measure

Appropriate size

hex or Torx® compatible keys

Torque wrench or torque screwdriver

with appropriate bits

Fat

Where

thread lock

for stem bolts

assembly compound

for carbon bars

Toe straps/zip ties

Cloths

A "threadless" stem refers to a system in which a fork with a threadless steerer tube extends through the steerer tube. A stem (A) then clamps around the outside of the steerer tube with spacers (B) if necessary.Finally, a top cap (C) keeps everything in place and acts as a helmet adjustment.

Threadless stem (A), spacers (B) and top cap (C)

Many older bikes and some lower end bikes have threaded steerers. The stems used with these systems are called "feather stems". For more information see

Rod Removal and Installation: Feather Rods

Threadless stems will typically have 1-3 pinch bolts (D) used in conjunction with a compression slot (E) to hold the stem to the steerer tube. They will also have 2-6 bolts (F) securing the faceplate (G), although in some cases they hook on one side and bolt on the other.

Pinch bolts (D) and compression slot (E)

Face Plate Bolts (F) and Face Plate (G)

Stems come in a variety of headtube and handlebar sizes. It's wise to measure your components to ensure you're installing or ordering the correct stem. Some common handlebar diameters are 22.2, 25.4, 26, 0, 31.8 and 35mm. There are outliers on some older bikes. Common steerer tube diameters are 1′′, 1 1⁄8”, 1 1⁄4” and 1 1⁄2” .

To determine steerer tube and bar diameters, measure where the stem clamps using a metric caliper. Be sure to be precise as some clamp diameters are within fractions of a millimeter each other and are not compatible with each other.

It is difficult to determine the clamp diameter of the shank by measuring it. The clamp diameter is usually stamped or labeled on the shank, but sometimes it is not. Incompatible components can be a safety hazard , so always check with the manufacturer for specifications and compatibility information.

Measure the center of the bar

Shank size is often marked on the shank

Stems also come in various lengths - measured from the center of the steerer tube to the center of the bar - and angles - usually between 0 and 20 degrees. These measurements are usually marked somewhere on the stem or its packaging. Stems can be installed in the up or down position to adjust the height of the bar without changing the orientation of the spacer. This is often referred to as positive and negative increase. modifications to case length may be required.

Positive rise (top) and negative rise (bottom)

The stems are usually accompanied on the head tube by spacers. These spacers are available in a multitude of different thicknesses, colors and materials. They allow height adjustment and also play a role in the adjustment of the helmet.

When installing a new stem, it is important to pay attention to the height of the stem and the amount of spacers you were using before. If you want to match the height of the original stem, measure from the top of the tire to the center of the handlebar and write it down for future reference. Note that a new stem may have a shorter or taller stack, which you will then need to account for with more, less, or different spacers.

The steering column spacers can be moved above or below the stem to change the height of the bar.

Measure at the center of the bar clamp if you want to replicate the height of the bar

This procedure can be done with the bike in a repair stand with the front wheel removed, or on the ground. It may be helpful to straddle the bike for added stability.