Control of the front wheel is essential to safe bicycling
If bicycle handlebars move suddenly, a rider can lose control and fall. There are several ways to prevent this through the use of shims or adhesives. Knurling, or making ridges in the metal for a firmer grip, is not recommended because it can produce defects that may cause the handlebar to crack. The handlebar and stem should be measured carefully before assembling the parts. Each method of securing the handlebar involves more complicated dis-assembly, if subsequent maintenance is necessary. Please be aware that this pertains to aluminum and steel handlebars and stems. Carbon fiber handlebars must be installed per the manufacturer’s specifications.
1. Loosen the handlebar binder bolt on a conventional stem, and slide the handlebar out to one side. Inspect it for any black streaks that indicate powdered aluminum from the friction of the parts. Clean both the stem and handlebar with alcohol.
2. Measure the handlebar and stem with a pair of vernier calipers. The internal diameter of the stem opening should be equal to or just slightly greater than the handlebar. In some cases, like old French handlebars, the gap will be large and the stem simply won’t bind on the handlebar. With properly fitting handlebars and stems, it is sometimes necessary to spread the stem slightly with a screwdriver as the bar is inserted.
3. Cut a shim from a soda can with the metal shears. Cut it slightly narrower than the stem so the edges don’t slice your hands. Curl the shim up and slide it between the handlebar and stem. Be careful as the edges are extremely sharp. Tighten the binder bolt and test the handlebar for tightness by putting your full weight on the drops.
4. Apply a thread locking compound between the handlebar and stem. Dis-assemble the parts and apply a thin film of thread locker to the handlebar. Slide it back into the stem and tighten the binder bolt. Allow the thread locker to cure for 24 hours before testing the assembly for tightness. Be aware that dis-assembling these parts will require heat and considerable force.
5. Apply high-strength epoxy — if all else fails — and re-assemble the parts. Allow the epoxy to cure for 24 to 48 hours. Once it cures, dis-assembling the parts will be almost impossible, so be certain the bar is in the correct position.