Mount a carbon handlebar

Composite does not like to work in compression. But this is how the handlebar and stem are fixed. So let’s see when we mount a carbon handlebar to preserve it!

Mechanical summary

The tools

To ensure the assembly of its carbon handlebars, it will require composite paste or « gripping » paste to isolate the hanger-potence-pivot connections, Allen keys (4 or 5 mm) or Torx keys (T25 or T 30) to tighten the different screws and a torque wrench to lock the whole properly. Composite ions sometimes have specific clampings as on this old generation FSA K-Force where the screws are reversed.

Pictures © Frédéric Iehl

Temps et difficulté

Allow about twenty minutes to assemble your composite handlebar. There is nothing really difficult, everything is in the placement and practicality of tightening. Because torque wrenches are more or less « easy » to use… And they are mandatory! So don’t hurry.

Stage 1

The pivot is degreased. Once well dry, any shims are placed.

Stage 2

The composite paste is then applied to the pivot.

Stage 3

The stem that has been degreased beforehand is placed.

If the pivot exceeds, an additional wedge is added above. There is more aesthetics, but if you need to raise your gallows you will be happy to have done that.

Stage 4

The steering hood and its compression screw are then placed.

The latter is tightened to set the direction temporarily. We can’t ride like that… The stem will have to be tightened.

Stage 5

We will degrease the hanger and the stem. It is necessary at all costs to avoid the slightest trace of lubricant that would make tightening completely ineffective. Even by squeezing very hard…

Composite paste is also applied here to increase the efficiency of the tightening torque.

Stage 6

We center the handlebar. When it’s new it’s easier, when it’s used we try to visualize the brands that remain…

Stage 7

The hood is placed by checking the centering. It will have been coated with front composite paste.

On the other hand, we grease the screws!

Stage 8

We start by installing a screw at the bottom.

The opposite upper screw is then placed.

We place the second screw from above.

And we put the last screw in place.

The screws are tightened evenly to keep the handlebar in place but allowing its rotation and sliding.

Stage 9

If necessary, we will adjust to the key. We don’t block anything, we just make tightenings that leave a small latitude of adjustment.

Stage 10

Once the screws are tightened, but not blocked, torque is tightened with the torque wrench.

It is first settled to the requested couple, usually between 4 and 6 Nm.

Depending on the configuration of the gallows, it is more or less easy to use… Here the tightening being placed on the back of the gallows, the gait is more complex than when it is done from the front. A ratchet torque wrench is then welcome. The one we use is fixed…

So we start tightening with the torque wrench. When the 4 screws are blocked, a complete tightening lap is done in the same way. Then we will be quiet.

Stage 11

The control levers will also be fixed by means of the torque wrench.

Stage 12

Once the clearance in the direction is adjusted, the stem can be tightened to finish the assembly of its carbon handlebars.

The stem is also tightened starting with the screw closest to the frame. So the one at the bottom.

We then move on to the top one.

We repeat the operation once in this direction and we are quiet! The use of composite or gripping paste increases the efficiency of the torque by about 1 to 2 Nm. Not negligible… In case of disassembly, it will be necessary to think about cleaning the surfaces. On the other hand, the slightest trace of lubricant makes the tightening ineffective. We then tend to exceed the pairs and split pivot hanger and stem….

Mechanical summary