How to Fit and Set Up Clip-On Aero Bars on Your Road Bike (Practical Guide)

The most cost-effective aero upgrade can also be fitted badly

Time trial aerobars on the road bike you already own are almost always the most direct way to gain speed without changing bikes: they narrow your frontal area to the wind and give you a second riding position for going fast. If you're still deciding whether they're worth it compared with a dedicated time trial bike, we cover it in detail in TT bike or road bike with aerobars?. Here we go one step further: you already have them (or they're on their way) and it's time to fit and adjust them properly.

And that "properly" matters, because almost all bad experiences with aerobars don't come from the part but from the fitting: crooked extensions, overtightened clamps, rests in the wrong place or the classic of wanting to ride in a time trial position for three hours on day one. None of that is hard to avoid. Let's go step by step.

Before you start: what you have in your hands

We'll use our CarboXtrem UCI Crono Aerobars as the reference, although the logic applies to any quality clip-on aerobar. On the UCI Crono, the extension —the part you rest on and grip— is carbon fibre, and the brackets that anchor it to the handlebar are 3D printed in PA12-CF, a carbon-fibre-reinforced nylon. That detail isn't cosmetic: because the bracket is made to fit your handlebar, the contact between part and tube is complete, with no improvised shims, and the assembly fits practically any road cockpit.

For fitting you need very little: Allen keys, a torque wrench (with carbon it isn't optional, we'll see why), and fifteen unhurried minutes.

Step 1 — Placement on the handlebar

The aerobars are mounted on the central section of the handlebar, one on each side of the stem. Three checks before tightening anything:

• Clean surfaces. No grease or tape residue in the contact area. The grip depends on friction between bracket and handlebar.
• Symmetry. Use the stem as the central reference and measure the distance from each bracket to it. Doing it by eye goes wrong more often than you'd think, and an asymmetric cockpit is noticeable as soon as you rest both forearms.
• Room for your hands. Check that the brackets don't get in the way of your hands' natural path to the brake levers. In the low position and during transitions, your fingers need clear access to the brakes.

Step 2 — Tightening: carbon doesn't forgive haste

More handlebars get broken here than on any pothole. The rule is simple: respect the maximum torque specified by your handlebar manufacturer —it's the most delicate component of the assembly—, tighten with a torque wrench and do it in stages, alternating bolts, so the clamp closes flat and doesn't concentrate pressure on one edge. If something turns at the correct torque, the solution isn't to tighten more: it's to clean the surfaces and use carbon assembly paste, which multiplies friction without adding a single extra newton.

We've dedicated a whole guide to this topic, with the typical mistakes of "it moves, so I tighten it": torque on carbon: how to mount your handlebar without breaking it. Everything said there applies word for word to aerobars.

Step 3 — Extension angle and spacing

There's no universal angle: there's the one that leaves your wrist in a neutral position, without bending it up or down while you hold the end of the extension. As an honest starting point for beginners:

• Start conservatively. Extensions with a slight upward tilt and comfortable spacing between hands. The pros' extreme position will come —or not— when your body accepts it.
• The wrist decides. If after a while you feel tension on the inside of your forearm or tingling in your fingers, the angle isn't yours yet.
• One change at a time. Angle, spacing, reach: change just one parameter per ride. If you change three things at once, you'll never know which one worked.

The advantage of a well-designed aerobar is that this fine-tuning doesn't require removing anything: you correct it and carry on testing.

Step 4 — The rests: where your forearm lives

In a time trial position, the weight of your upper body rests on your forearms. That's why all CarboXtrem aerobars have 3D lattice rests —the same family of printed structures we use in saddles and grips— instead of a flat rubber pad: they spread pressure over more surface and breathe. Position them so your forearm rests on its wide part, neither digging into the elbow nor rubbing the wrist, and check that you can slide your arm slightly to reposition without losing support.

Step 5 — Adaptation: the mistake of debuting the position on a long ride

The time trial position has to be trained, just as threshold does. For the first few days you'll feel it in your neck and lower back and get a certain "twitchy bike" feeling when steering from the centre of the handlebar. It's normal and it passes, but only if you build up gradually:

• First rides: short stretches in the aero position, on familiar, flat roads without tricky traffic. Alternate with your normal position.
• Gradually lengthen your aero blocks, ride by ride, as the aches disappear.
• Leave descents, tight corners and groups for the usual handlebar position: aerobars are for riding fast and straight.
• Remember that moving your support forward slightly changes your weight distribution on the bike; if new aches appear when sitting, check your saddle too — here's how: saddle height: how to set it right.

Signs that something isn't positioned correctly

The UCI Crono at a glance

And if you'd rather not fit them on your own

Every order of CarboXtrem UCI Crono Aerobars includes a detailed after-sales guide and personalised support: if any step isn't clear, message us and we'll sort it out with you, with your handlebar and your case in front of us. Fitting them properly is quick; fitting them properly with help is quicker still.

Frequently asked questions

Do time trial aerobars fit any road handlebar?

In the case of the CarboXtrem UCI Crono, yes in practice: the mounting brackets are 3D printed in PA12-CF to fit the handlebar, so they fit practically any road cockpit.

What tools do I need to fit them?

Allen keys and a torque wrench. On carbon components the tightening torque must always respect the maximum specified by the handlebar manufacturer, tightening in stages and alternating bolts.

How long does it take to adapt to the time trial position?

It depends on the rider. The safe approach is progressive: short blocks in the aero position during the first rides, lengthening them little by little as your neck, lower back and forearms get used to it, and changing only one adjustment parameter at a time.

Can I remove the aerobars when I don't need them?

Yes. They're components mounted on the handlebar with clamps, so they can be removed and refitted; just repeat the same care each time you fit them: clean surfaces, symmetry and correct torque.