How much faster are TT bars? I tested them at the same power

TT bars (also called tri bars, aero bars or clip-on extensions) made me 2 minutes and 9 seconds faster over 10 miles at exactly the same power — a gain of 1.7mph. For most club riders, clip-on TT bars are worth somewhere between 1 and 2mph at the same effort, which is roughly 2 minutes over a 10-mile time trial, 4–6 minutes over 25 miles and 20–25 minutes over 100 miles. Starting from around £50, nothing else you can bolt to a bike comes close for the money.

But there is a catch, and it is the bit almost every article skips: the bars only pay you back if you can actually hold the position and produce power in it. That is a training problem, not a shopping problem. More on that below.

What are TT bars?

TT bars are forward-facing extensions that let you rest on your forearms with your hands out in front of you and your elbows tucked in narrow. They come as standard on time trial and triathlon bikes, but the version most riders buy is the clip-on kind, which bolts onto a normal round 31.8mm road handlebar in about twenty minutes with a single Allen key.

You will see the same thing called tri bars, aero bars, clip-ons or extensions. They are all the same idea: get your body narrower and lower, and stop your arms and chest acting like a parachute.

My own test: 10 miles, 250 watts, with and without tri-bars

I'm always being asked “how can I get faster on the bike?” and although training harder will increase your speed if done in a structured way, there is another option which is a must for anybody wanting to go faster at time trials or triathlons.

I always felt that having bars made me about 2 miles per hour faster when I had them fitted to my road bike, but without a power meter it was hard for me to be sure. Not only do they make you lower, they also bring you narrower, making you more aerodynamic.

‘the rider accounts for around 80% of the drag while riding’

So I decided to do an experiment and ride the same 10-mile TT course at a constant 250 watts to see the difference. I was 2min 9sec faster on the TT bars for the same power, which works out at 1.7mph.

To put that in context: the same 250 watts took me from roughly 21mph on the hoods to roughly 22.7mph on the bars. Same course, same rider, same legs, same effort. The only thing that changed was where my arms were.

What that saves you over a longer distance

If you multiply that up in distance you can really see how it saves a massive amount of time for no extra effort:

• Olympic triathlon (24 mile bike leg) – 5min 20sec faster
• Half iron distance triathlon (56 mile bike leg) – 12min 26sec faster
• 100 mile ride – 22min 12sec faster
• Iron distance triathlon (112 mile bike leg) – 24min 52sec faster

How much faster will TT bars make you?

My numbers are my numbers. You are a different size, riding a different bike, at a different speed. So here is a more general version.

The table below models the time you would save by adding well set-up clip-on bars, at the same power you ride now. Find the row for your event and the column closest to your current average speed on a flat, solo ride.

Modelled on a 20% reduction in drag (CdA 0.40 on the hoods to 0.32 on the bars), 80kg total rider and bike weight, flat road, still air, same power throughout. Your own result will vary with body size, kit and how well the bars are set up.

Two things are worth noticing in that table.

Faster riders gain more speed but save less time. A 23mph rider picks up 1.7mph, a 15mph rider only 1.0mph — because drag rises with the square of speed, so there is more of it to remove when you are going quickly. But the slower rider is out on the course much longer, so the clock saving is bigger. Everybody wins, just in different currencies.

My measured result was slightly better than the model. The model says a 21mph rider gains 1.5mph; I measured 1.7mph. That is because my baseline was a relaxed road position on the hoods rather than a tucked position in the drops. The more upright you currently ride, the more there is to gain.

Why TT bars work: you are the drag

Above about 30kph on the flat, roughly 80–90% of the power you produce is going into pushing air out of the way. Not the tyres, not the chain, not gravity. Air.

And of that air resistance, roughly 70–80% is you, not the bike. Which is why a £50 set of clip-ons that changes the shape of the rider beats a £2,000 set of wheels that changes the shape of the bike.

Clip-on bars do three things at once:

• Narrow you. Your elbows come in from shoulder width to a few inches apart. This is the single biggest effect and it is free.
• Lower you. Your torso drops and your frontal area shrinks.
• Smooth you. Your forearms sit in line with the airflow instead of across it, and your shoulders roll forward to fill the gap between your arms and your head.

What the independent testing says

My test was one rider on one road. Here is how it lines up against controlled testing, so you can see it isn't a fluke:

• Wind tunnel (Silverstone Sports Engineering Hub, tested for BikeRadar): clip-on extensions saved around 31 watts at 35kph versus riding on the hoods — the biggest single gain in their whole test, and by far the cheapest per watt.
• Outdoor velodrome (AeroCoach): moving a rider from a relaxed position on the hoods into clip-on extensions took him from 40kph to 43.3kph at the same power. They also found the extensions were faster than the drops, and more comfortable to hold.
• The reverse warning: that same AeroCoach testing found bars fitted to the bike but not being used cost about 9 watts. If you leave clip-ons on your winter bike all year and never use them, you are paying a small tax for nothing.

One honest caveat: the gain is speed-dependent. Testing at Bespoke Cycling found a rider who saved 60 watts at 40kph actually lost around 10 watts at 23kph. Below the mid-20s kph — grinding up a long climb, say — the aero position is not doing much for you, and the closed hip angle may be costing you. Aero bars are for going fast on the flat and the rollers, not for climbing.

The bit everyone skips: you have to train in the position

This is where most riders waste their money.

Getting aero is easy. Producing power while you are aero is not. When you drop your chest towards the top tube you close down your hip angle, restrict your breathing and put your glutes and hamstrings at a mechanical disadvantage. In a study of 19 trained cyclists published in the Journal of Sports Sciences, taking riders from a 24° torso angle to a flat 0° torso angle cost them 14% of peak power — around 51 watts — and pushed their oxygen cost up by around 4% at submaximal intensity.

Think about what that means. If the bars buy you 30 watts of aerodynamic saving and the position costs you 40 watts of output, you have made yourself slower and you will never know why, because your average speed went down while your bike got more aero.

The good news is that most of that cost is trainable. Riders who spend consistent time in the aero position adapt to it: hip and hamstring flexibility improves, neck and shoulder tolerance improves, and the power gap between your road position and your aero position closes. Coaches working with time triallists generally look for 4 to 6 weeks of regular riding in position before expecting threshold power to come back, and considerably longer if you have overhauled the position completely.

But it only happens if you deliberately do the work. Turning up on race day having bolted the bars on the night before is how people end up 3 minutes slower with a sore neck.

How we train the position at Ride Harder

This is exactly why time in position is baked into how I structure training rather than left as an afterthought. Sessions get prescribed to be ridden in the position, not just at a power number — starting with short blocks at endurance pace where holding the shape is the only goal, then progressively longer threshold intervals in position as your body adapts. The rest of the picture matters too: hip mobility, thoracic extension and posterior chain strength are what let you hold a low front end for an hour without your lower back giving up.

• The Ride Harder Academy — 12 weeks of coached, structured training with the strength, mobility and mindset work alongside it. The gym and mobility side is what makes an aggressive position sustainable, and it is the first thing riders drop when they train alone. Next intake starts in October.
• The Ride Harder Plan — the same structured 16-week block to follow at your own pace, including the strength and mobility programme.
• Smash your 10 mile TT PB and Smash your 25 mile TT PB — 6-week race-specific blocks if you have a date in the diary.
• Want it built around your position, your events and your week? 1-to-1 coaching.

Whichever route you take, you also need to know your numbers before you start. Here's how to test your FTP properly — and if you don't fancy a full test, you can estimate your FTP without one.

How to set up clip-on TT bars

You do not need a lab to get 90% of the benefit. Start here:

1. Elbows narrow. Pads set just inboard of your thighs. Narrow elbows alone are worth around 4% of your total drag in wind-tunnel-validated testing — it is the cheapest gain on the list and it costs nothing.
2. Forearms roughly horizontal. Elbows sitting just behind the pads, not perched on the front edge of them.
3. Shoulders rolled forward, head tucked between them. A flat-ish back matters more than an extremely low one.
4. Don't slam the front end. This is the most common mistake. Field testing has repeatedly found riders who are faster with the pads raised a centimetre or two, because they can hold the position, breathe, and still see up the road. Low is not automatically fast.
5. Try tilting the extensions up 15–20°. In the Silverstone wind tunnel testing this was worth another couple of watts over flat extensions, and most people find it more comfortable.
6. Consider nudging the saddle forward slightly. Adding bars to a road bike closes your hip angle; a small forward shift opens it back up. Change one thing at a time and ride it before changing the next.

If you are starting from scratch with your position, my guide to setting up your road bike in 5 easy steps is the right place to begin, and how to become more aero on your road bike covers the free gains you can make before you spend anything at all.

Are TT bars allowed in your event?

This trips people up, so check before you enter:

• UK time trials (CTT): clip-on bars are permitted in standard open events — this is the mainstream UK TT scene. They are not permitted in the CTT Road Bike category, which bans aerobars, clip-ons and extensions outright. Always check the current CTT regulations for the category you are entering.
• Mass-start road races (British Cycling / UCI): banned. Under UCI technical regulations only traditional handlebars may be used outside of time trials and pursuits, and British Cycling enforces this domestically.
• Triathlon: fine in non-draft racing, which covers most UK middle and long-course events and all IRONMAN racing. In draft-legal racing they are heavily restricted — extensions must not reach past the foremost line of the brake levers, must be bridged, and the height difference between bar and armrest is capped. Check the current British Triathlon rules for your event.
• Sportives and club runs: usually a no. Many UK clubs ban them on club runs outright, and they are generally not welcome on British Cycling-sanctioned sportives.

A word on safety

On the bars your hands are nowhere near your brakes and your arms are close together, which makes it harder to hold a line — especially in a crosswind. That is exactly why they are banned in bunch racing.

British Triathlon's guidance is worth following: practise on a quiet road or a closed circuit first, get comfortable moving in and out of the bars smoothly so you can reach the brakes, keep your eyes up the road rather than down at your wheel, and get out of the bars early for junctions, corners and traffic. Build the handling habit in training, not on race day.

So — are TT bars worth it?

For a solo effort on flat or rolling roads at 30kph and above: yes, and it is not close. Around £50–£150 for 1–2mph at the same effort is the best value upgrade in cycling, and no set of wheels or aero frame will touch it per pound spent.

For group riding, climbing, or if you are not going to spend any time training in the position: no. Save your money and put it into the engine instead.

Frequently asked questions

How much faster are TT bars?

At the same power, clip-on TT bars are typically worth 1–2mph, or roughly 2 minutes over a 10-mile time trial and 4–6 minutes over 25 miles. In my own test at a constant 250 watts I was 2min 9sec faster over 10 miles — a gain of 1.7mph.

Can you put TT bars on a road bike?

Yes. Clip-on extensions fit any standard round 31.8mm (or 26.0mm) handlebar and take about twenty minutes to fit. They will not fit some flat or oval-profile aero handlebars, so check your bar shape first.

How many watts do aero bars save?

Wind tunnel testing has measured around 31 watts saved at 35kph versus riding on the hoods. Velodrome testing has found even larger savings when the rider starts from a relaxed, upright road position. Expect 20–40 watts for most riders at typical time trial speeds.

Do you lose power in the aero position?

Usually a little, at first. In one study of 19 trained cyclists, going to an extreme flat-backed position cost 14% of peak power. Most riders lose far less than that at a sensible torso angle, and the gap closes considerably once you have spent 4–6 weeks regularly training in the position.

How long does it take to get used to TT bars?

Expect 4–6 weeks of consistent riding in position before your threshold power in the bars catches up with your road position, and longer if you have made a big change. Build up gradually — short blocks at endurance pace first, then longer efforts at threshold.

Are TT bars allowed in road races?

No. UCI technical regulations permit only traditional handlebars in mass-start road races, and British Cycling enforces this at domestic events. They are permitted in time trials and, in most cases, non-draft triathlon.

Do aero bars slow you down if you don't use them?

Slightly, yes. Testing found bars fitted but unused cost around 9 watts at 40kph. If you only race a few times a year it is worth taking them off in between.

Should I get as low as possible on the bars?

No. Field testing regularly finds riders are faster with the pads raised a little, because they can hold the position, breathe properly and look up the road. The fastest position is the lowest one you can hold at full power for the whole event — which is usually not the lowest one you can get into for ten seconds in the garage.

Next step

Bolt the bars on, then earn the gain. Get time in the position into your training week, build the hip mobility and posterior chain strength that let you hold it, and the 2 minutes the bars give you becomes 4.

👉 Join the Ride Harder Academy — 12 weeks of structured training, strength and mobility work, and a group of riders doing it alongside you. Next intake starts in October.