Handlebars and Stem

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DESCRIPTION: (M) Mountain bikes often have almost straight handlebars, and the bars are often held by one or more binder bolts in a custom chrome-moly steel tube stem. The handlebars may have bar ends attached by binder or expander bolts.

The curved-down drop bars are most common on road bikes. Typically, they are held in a slick, smooth, aluminum stem by a binder bolt, which is often hidden from view. You can add a clip-on aerodynamic bar to your drop bars, but the resultant riding position is pretty unstable. Not worth the danger unless you are a time trialist or tri-athlete. By the way, the faddish, upside-down position for drop bars is also unsafe. It invites impalement. You like it? You can have it.

(C) Most cruisers have all-rounder-type bars, which are close to flat, but are curved near the ends so the grips aim more toward the back of the bike. The stems on cruisers are usually inexpensive versions of the stems used for road bikes.

DIAGNOSIS: (C, R, M) For some reason, people often get con fused about just what holds what in place on the handlebars and stem. The following symptoms tell you what part of the setup is loose.

(C, R, M) If the handlebars swivel up and down, so you can twist them in the stem, then your problem is a loose binder bolt. If the bars are loose in relation to the front wheel, so they tend to aim off to one side or the other when you are riding straight ahead, the problem is a loose or cockeyed stem. If you have a bar end that is loose, all you have to do is line up the loose bar end with the other one, then tighten the mounting bolt that squeezes the bar end around the end of your handlebar, or the expander that goes in the end of the bar. If your handlebars are too high or too low, this also requires working on the stem, not the headset as you might suspect. One exception to this rule is the type of stem that works as a locknut for the headset. You can’t adjust the bar height with that kind of stem. To raise the handlebars, you have to buy a taller or more upright-angled stem.

(C, R, M) No matter what you’re doing to either your handlebar or stem, check to see that the tips of the handlebars or bar ends are plugged. If they aren’t, plug them immediately—before you get back on the bike and start riding. If you don’t have official bar plugs with you, use a wine or champagne cork, or even a short piece of stick with the end rounded off. Bare bar tips can gore you if you fall on them. I know this from experience.

PROBLEMS: (C, R, M) Loose binder bolt. Tighten the bolt with an Allen key (usually 5 or 6 mm). Some beefy stems have two or even four binderbolts; tighten them all evenly, turning each a bit at a time.

(C, R, M) If your bars slip because they are simply too small in diameter for your stem, loosen the binder bolt as much as possible, then find a smooth, uncrumpled aluminum beer or pop can (all too easy to find on many back- roads and trails). Cut out a 3-inch by 2 1/2-inch strip of the side of the can with a sharp knife, being careful not to bend or kink the metal. Use the strip you cut out as a shim, wrapped around the bulged central portion of the bars where they fit inside the stem. Tighten the binderbolt as well as you can, and, when you get home, replace the bars or stem to get a better fit.

(C, R, M) Loose or cockeyed stem. To straighten bars that have gotten cockeyed, stand in front of the bike and hold the front wheel between your legs (you don’t have to get weird with it, just hold it still). Grasp the handlebars firmly with both hands and straighten them so the stem extension lines up with the front wheel and the bars run straight across, perpendicular to the line of travel of the front wheel. If the bars won’t budge, on most stems you loosen the expander bolt, using an Allen key, then tap the head of the bolt with a hammer, rock, or something, to unwedge the stem so it can be straightened.

(M) If you have one of those stems that acts as a locknut for your headset, it has binder bolts instead of an expander bolt, as shown in Fig 3-2. Loosen the binder bolts if you need more looseness to move the stem. DON’T loosen the Allen bolt at the top of the stem where most stems have their expander bolts; LEAVE THAT BOLT ALONE. Just loosen the binder bolts, then adjust the bars so they’re straight.


3-1 Handlebars


3-2 Top: Standard Stem; Bottom: Locknut Stem

(C, R, M) D Once your stem and handlebars are straight, tight en the stem expander bolt (hinder bolts, you fancy stem people) enough so the stem will stay put, but no tighter. Try twisting the bars again. If they stay put unless you pull quite hard to one side, the expander bolt is tight enough. It should not be so tight that the stem can’t slip in case of a crash. If you fall on the bars, you want them to give, not you.

(C, R, M) Stem creaky, cracked or broken. When you ride up hills and pull hard on the handlebars, your stem creaks. First check to see that it isn’t loose; tighten the expander bolt as described in the previous section. Also check to make sure the shaft of the stein, where it binds to the steering column that comes up from the fork, is well greased. Grease on the threads of all binder and expander bolts is a must, too. Then check for cracks on the stem, and look closely to see if it is the correct diameter; it should just barely slip down into the fork column in the headset.

(C, R, M) If you find any signs of cracks on the stem, especially at a joint or near the binder bolt, ride home gingerly, without pulling up hard or leaning down hard on the bars. If your stem is broken and you’re miles from help, here’s an emergency fix. Undo the front brake (undo the transverse cable so it won’t catch on the knobbies), tie or balance the bars on what’s left of the stem, then ride home holding the stump of the stem, pulling on the rear brake cable where it runs bare along the top tube in order to stop. If you have no exposed section of cable running to your rear brake, you have to steer with one hand on the stem stump while you squeeze the brake lever with the other hand. Very tricky. Proceed with due caution.

(C, R, M) When you get home, use the handlebars bro ken procedure to take the bars off the bike, then replace the stem and put the bars back in, as described at the end of the broken handlebar procedure.

(C, R, M) Handlebars too high or low. To adjust the height of the handlebars if you have a standard stem, you have to loosen the expander bolt a couple of turns with an Allen key, then tap on the head of the bolt with something heavy like a rock or a hard piece of wood. A short piece of 2-by-4 with a knot at one end works fine. When the expander bolt is unwedged, undo the front brake transverse cable, then lower or raise the handlebars. Tighten the expander bolt as explained in loose or cockeyed stem, above. If you need to readjust the front brake, see PROBLEMS in the Brake Cables section.

(M) If you have one of the fancy stems that acts as a locknut for the headset, you can’t adjust the height of it. You have to buy a new stem that is taller or that has a more upright angle. Seems like a fairly expensive and labor-intensive way to adjust your bar height, no?

(M) Drop bar bent in. You’ve taken a spill? You are scraped and shook up, but OK. The bike is OK too, except that one of the handlebars has a new bend in it, so that it toes in. When you stop shaking, put the bike on its side so that the still-straight bar is flat on the ground. Step on the drop portion of the straight bar (careful, don’t break the brake lever) and pull firmly upward on the folded bar. If the bars are aluminum, you might be able to get them straight enough to ride. Steel bars are a lot harder to bend. And any bar that has been bent and unbent is weak, so when you get a chance, get a replacement.


Fig. 3-3 Straightening a Bent Drop Bar

(C, R, M) Handlebars broken; replacement. First get any grip, tape, brake levers, bar ends, horn, or whatever off the old ones. If you have lots of trouble removing old hand-grips, take the bike to a bike shop or garage, ask them if you can use the cleaning nozzle on their shop air hose, then stick the nozzle in the hole at the end of one hand-grip, put your thumb over the hole in the other grip, and blast air pressure into the handlebars. Nine times out of ten the grips will both come loose and slide right off. For that tenth tough grip, use a razor knife and lots of care to cut it off. Then loosen the binder bolt completely. Slide the bars out and take them to a shop. Get some that are the same diameter at the stem or a little smaller. If you get smaller ones, buy the correct size shim to make the new bars fit the stem. Don’t get bars that are much too big for your stem—they will stretch and weaken the stem.

(C, R, M) If the bars are just a hair too big, you can do a neat trick to open up the stem if you have the kind of binder bolt that screws into a threaded hole. Take the binder bolt all the way out, turn it into the threaded hole from the back side, stick a penny into the slot there, and tighten the back ward binder bolt up against the penny to spread the stem opening a little.

(R) Tape worn or unwound. Take the plugs out of the ends of the bars. If there is a screw in the middle of the plug, unscrew it until it is loose, then push it in and work the plug out. If your plugs don’t have screws, just yank them out. Unwind the old tape completely. Get new tape. I recommend either cloth, thin leather, or the rubbery, stretchy type of plastic tape that is thicker in the middle than at the edges. You can use the extra-thick tape, or you can put on several layers of standard tape for a softer fee! on your bars, but the cushiness can get to the point where you are out of touch with that zingy responsiveness of your bike’s front end. Start wrapping the tape about 3 inches out from the mid-point of the bar where it is held by the stem. If the tape has no gum on it, you can stick the end down with a little piece of Scotch tape. Whichever type of tape you use, start by wrapping a couple turns in one place to cover the tape end. As you lay the tape on, keep it tight, and make it go directly from the roll to the bar. There’s less to get tangled up that way. Overlap at least a third of the tape’s width at all points. At the bends, you have to overlap more on the inside than on the outside. Just make sure it overlaps enough on the outside of the bend.

Fig. 3-4 Drop-Bar Taping

(R) Angle the tape across the bar behind the hand lever, making sure it is tight all the time, (See Fig. 3-4.) You can f the hood up on most hand levers, so you can wrap tape close around the lever’s post. At the end of the bar, leave a little tape to tuck in under the plug. When you’ve finished taping and tucking, push and knock the plug back in with your hands. Don’t use a hammer; it will mash the tape in two and you’ll have to start all over. If you have tape left over, you can wrap it around the top tube of the frame where the handlebars hit if they are swung all the way around. Or you can put a little over the hole at the top end of your seat post, if you have a post with a hole at the top. Or you can use a little on a leaky vacuum cleaner hose, or a noisy kid’s mouth, or a cracked pump handle. Sometimes I feel like my whole mish-mosh life is held together by scraps of handlebar tape and used bike inner tubes.

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Modified: Wednesday, November 15, 2023 3:04 PM PST