When a bike’s handlebar is too low, you’ll know about it. Symptoms include tingling and numbness in the hands, aches and pains in the shoulders, neck, and lower back, and soreness or numbness in the nether regions. The same problems can result from the handlebar being too far forward. Handlebar reach and height are linked because the steering axis on bikes isn’t vertical (90 degrees). It slopes at somewhere between 65 and 75 degrees. So raising the handlebar also brings it closer towards you. The result is that you’ll sit more upright.
How upright should you sit? Let your own comfort be your guide, not what sports-oriented magazines or bike-fitting formulae suggest. A too-low handlebar is particularly common on road bikes.
You should be able to raise the handlebar without changing anything else. If you raise it significantly, however, the brake and gear cables may be too short. The cables need to be replaced if the outers are taut, especially if they restrict the steering.
What kind of stem do you have?
There are two common designs: one that clamps the fork’s steerer tube internally; one that clamps it externally. The former, called a quill stem, tends to be found on older or cheaper bikes; the latter, called an Ahead stem, is the dominant design on modern bikes.
Quill stems use threaded headsets while Ahead stems use threadless headsets. In a threaded setup, the top part of the headset screws onto threads on the steerer tube, which must be cut precisely to length, and a locknut holds everything in place. The steerer tube does not extend beyond the headset.
In a threadless setup, the headset fits over the steerer but isn’t screwed on. The steerer tube isn’t cut so short; it passes up through the headset, the stem, and any spacer washers. The headset is held in compression by the cap on top of the steerer tube (the top cap). In order for this to work: the combined height of the stem and spacers must overtop the fork’s steerer tube by 2-3mm; and the top cap must be screwed down not too tightly and not too loosely. The spacers on the steerer can sit above or below the stem. The more spacers there are, the more height adjustment you’ve got.
Raise your stem: Ahead/threadless
If there are spacer washers above the stem, you can fit one, some, or all of them below the stem instead. Undo the top cap with an Allen key and remove it. Partly undo the Allen bolt or bolts at the side of the stem where it clamps the steerer. Slide the spacers and the stem (still fastened to the handlebar) up and off the steerer, then reassemble with the spacers beneath the stem.
When you refit the top cap, tighten it so it’s just snug but not tight. Orient the stem and tighten the side bolt(s) firmly. Holding the handlebar, lift the front wheel off the ground and turn it side to side. It should turn freely. Now check for play in the headset. With the front wheel on the ground, apply the front brake and try to rock the bike backwards and forwards. Hold your other hand around the headset to feel for any play as you do this. If there is any, loosen the stem’s side bolt(s), tighten the top cap a little more, tighten the stem’s side bolt(s), then repeat the checks for free steering and headset play, as above.
Ahead stems can be fitted either way up on the steerer. Since they’re angled at anything from five to 40 degrees, that gives you two handlebar heights to choose from. To flip the stem over, you’ll need to remove the handlebar first. Just undo the two or four Allen bolts in the stem’s front face. Then follow the advice above on moving the stem, flipping it over before you refit it, and refitting the handlebar before you check for smooth, play-free steering.
Raise your stem: quill/threaded
Undo the bolt in (or on) the top of the stem. It will rise upwards as you undo it. Once it’s 1cm or so proud of the stem, tap it firmly with a mallet. This will release the internal wedge bolt’s grip on the inside of the steerer.
Raise the stem to the desired height, but not above the minimum insertion mark on the side of the stem, then firmly tighten the stem bolt. To check it’s tight enough, stand in front of the bike with the front wheel gripped between your legs and try to turn the handlebar left and right.
Fit a new stem: Ahead/threadless
Stem at the top of the steerer and the handlebar’s still too low? Time for a new stem. Caution: while you will want a steeper stem angle and may want a different stem length, the stem’s steerer diameter and handlebar diameter must match those of your existing stem. These will probably be: steerer, 1 1/8 inches; handlebar clamp, 31.8mm or 25.4mm. Go to your local with your bike (or stem) if unsure.
What length and angle stem should you get? Use an online stem comparison tool to see what difference other stems will make compared with your current stem. Alternatively, buy an adjustable angle stem and try different settings until you hit on one that works.
A new stem: quill/threaded
When you’ve reached the minimum insertion line and want to go higher, you need a new stem with more vertical rise and a shorter forward extension. Quill stems are available with a rise of up to a foot!
Fitting a new quill stem is awkward as most don’t have a separable handlebar clamp, so you must first remove the brake lever, shift lever, and grip or bar tape on one side of the handlebar to remove it from the stem. On the plus side, you still don’t have to mess with the headset.
Time for a raise?
You can extend the length of the fork’s steerer tube with a stem raiser. This is essentially an auxiliary bit of steerer tube that clamps into (quill) or onto (Ahead) the existing steerer. You fit your stem to that.
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