Inserting a Handlebar into a Stem

Inserting a handlebar into a classic stem requires a few simple tricks. Grand Bois stems are based on classic stems, and are not equipped with removable faceplates that can make installation easier.

Classic stems have a number of advantages that are worth the small hassle during installation:

  • The clamp tightens around the handlebars on all sides with even pressure (like a hose clamp), whereas a stem with a removable faceplate puts stresses on the bars at the two gaps. These stresses increase the risk of handlebar failure.
  • A classic stem can clamp the handlebars more tightly without crushing them. This eliminates the risk of the handlebars rotating as you hit a bump. With a removable faceplate, there is a thin line between not enough clamping force and deforming the handlebars.
  • The larger bolts of a classic stem easily can support a decaleur.
  • The removable faceplate’s extra bolts add weight. To keep the weight acceptable, many stems use smaller and shorter bolts, which can result in stripped threads.

Of course, many stems with removable faceplates have proven themselves in everyday use. Most are fine, but given a choice, I prefer the smarter design. If you install handlebars frequently, like a bike shop, you may prefer removable face plates. For the rest of us, we only replace our handlebars when we build up a new bike or if our handlebars get bent in a crash. Installing handlebars in a “classic” stem takes only a few minutes, if you know a few simple tricks:

Above you see the tools you need, in addition to the stem and handlebars: an M5 screw and nut, a thin coin (or other thin piece of metal), wrenches to tighten the screw and nut, and masking tape.

Insert the nut into the slot of the stem, then thread in the screw. Grand Bois stems use M6 bolts, but I used a smaller M5 nut and bolt, because the nut is thinner. (You can also file an M6 nut until it fits with a little room to spare.) Now flex the bolt gently so the stem slot opens enough to slide in the coin. (In North America, dimes are the thinnest coins. The coin will get scratched, so don’t use a collectible one.) Place the coin so it sits underneath the screw hole of the nut, not just the edge. Make sure the coin does not protrude into the handlebar “hole.”

Now turn the screw clockwise while holding the nut in place. As the screw emerges from the bottom of the nut, it pushes against the coin and opens the slot.

A well-designed steel stem is like a hose clamp: It is easy to open. (Some lugged steel stems have reinforcement ridges that stiffen the clamp. Not only does this make it difficult to open the stem, but it also means that the stem cannot conform to the shape of the handlebars as it clamps them.)

Don’t overdo this step, as you could crack the chrome-plating. You can always open it more during the handlebar installation.

You also could use a wedge (like a screw driver), but that is likely to get in the way when you install the handlebars, or fall out when you are in the middle of the installation.

Steel is harder than aluminum, and a steel stem easily scratches your aluminum handlebars. To prevent unsightly scratches where you won’t have handlebar tape, wrap the exposed portion next to the center bulge with masking tape. Masking tape does not stretch as well as handlebar tape, so start with a ring at the edge of the bulge.

Then wrap the masking tape at an angle, until it extends as far as needed.

Hold the stem over the bars in the position where it will be placed. These steps help ensure that you don’t install the handlebars upside down!

Now follow the handlebars so you arrive at the end with the stem in the correct orientation.

Insert the handlebars into the stem. Guide the stem around the bars. Keep the slot on the outside of the bend. That keeps the sharp edges of the slot away from the bars. If the stem quill interferes with the handlebar bends, back out the stem and rotate it before trying again.

Be careful not to force it. Deep scratches form stress risers that can lead to premature failure of your handlebars. If the clamp is too tight, open it further by turning the screw clockwise against the nut.

Once the handlebars are in place, remove the screw, nut and coin. Insert the  bolts and nuts that were supplied with the stem. Tighten them. Make sure your handlebars don’t move until you have tightened the bolts, otherwise, they can get scratched. Then remove the masking tape and install brake levers, cables, etc.

To remove the bars, use the same procedure in reverse.

About Jan Heine

Spirited rides that zig-zag across mountain ranges. Bicycle Quarterly magazine and its sister company, Rene Herse Cycles, that turns our research into the high-performance components we need for our adventures.
This entry was posted in Handlebars, Product News, Stems, Testing and Tech. Bookmark the permalink.

8 Responses to Inserting a Handlebar into a Stem

  1. Bob says:

    Jan, thanks for this tip. I had not thought of such an approach. What I did was modify a pair of lock ring pliers using a grinder so the jaws would just fit into the stem slot, without going into the bars. It required more dexterity to keep pressure on the stem as I was maneuvering it onto the bars, without scratching the bars. The stem I was using (a modern tig welded steel stem) did not have much of a gap for the slot, so I’m not sure if using a bolt and nut would have worked.

  2. Leonard says:

    Jan, Thanks for this well-written and illustrated tip/trick on how-to-do. Lenny

  3. Jim V says:

    Jan, what a great tip! I never would have dreamed to spread the clamp in that fashion… This is perfect timing as I am getting ready to install a new stem on my noodle bar.

  4. Frank says:

    A very useful tutorial! There is only one thing left that I would love to know a hint how the Pros are doing it: How do you make sure that the stem is in the center of a handlebar, which like the GB handlebars is not marked with a scale or some logos at the center bulge? I always stuggle with that task …

  5. Walt says:

    Nitto actually makes a tool that spreads the clamp. Having used it, your way seems much better.

  6. mark says:

    Excellent, helpful post!

Comments are closed.