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I participated in the Nice Ironman this year and did not make the bike cutoff. I have signed up for 2024 and using 2023 to make the improvements to get me through that race.

The first 80 miles (128 km) is an 8,000 foot (2440 m) climb, or 2% average grade, with two significant climbs (Col de l'Ecre and Col de Vence) with 3 passages between 10% and 15%.

Question - Will a tri bike help me conquer this race? I rode with a Giant TCR Advanced Pro 1 Disc this year.

2022 Giant TCR Advanced Pro 1 Disc from company's website

The Event:

enter image description here enter image description here both images from https://pjammcycling.com/triathlon/148.IRONMAN-France-Nice-Bike-Course-and-Profile;mode=Profile

Thank you for the responses. The benefits from your responses, it'll probably improve my run time, I need to train on it in 2023 to get comfortable in the Aero position.

Concerns - I'm not one for speed on the road, and get nervous with wind and turns. Controlability will be a thing for me.

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    To clarify, the first 80mi "IS" an 8000 ft(?) climb or the first 80mi "HAS" 8000 ft(?) of climbing?
    – Ealhmund
    Dec 22, 2022 at 16:35
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    What do other people use on the same (or similar) course?
    – Michael
    Dec 22, 2022 at 17:11
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    I've added some pictures - is this the right event ?
    – Criggie ♦
    Dec 22, 2022 at 18:16
  • Maybe you should compare your times on Strava with the quickest guys on the sections of the race, to check if you are too slow on the flats or on the climbs. A tri bike is usually designed to be aero, but to climb you need a light bike and a good gear ratio for the climbing... sometimes even a foldable from the 70s do the job youtu.be/tJO-2zikACk?t=51 :) .
    – EarlGrey
    Dec 23, 2022 at 9:25
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    I assumed replacing my cheap, heavy, clumsy, department store bike with a much lighter road bike with a great drive system and much smaller profile would be an instant benefit to my pace. It wasn’t - I sped up by maybe 1%-3% just by switching bikes. What it did do was give me a bike that I could more easily train up with. My conclusion was that the cheap bike slowed down my training much more than it slowed my pace.
    – Todd Wilcox
    Dec 23, 2022 at 17:01

5 Answers 5

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TL;DR: It depends.

Using my own data on BestBikeSplit, the rough answer is that switching from a road bike to a tri bike will likely improve your time. Even though Ironman Nice is a hillier course, aerodynamics make more of an impact on your time. However, that's with a number of assumptions, namely (off the top of my head):

  • You're able to get into (and maintain) a more aerodynamic position on the tri bike than you currently have on the road bike.
  • You're at least as comfortable riding the tri bike as you are on the road bike, especially climbing and descending. For instance, saving 5min due to improved aerodynamics is meaningless if you're losing 10min due to poor braking on the descents.
  • You don't have too large a power drop in your aerodynamic position on the tri bike compared to the road bike. It's not uncommon for a rider to have a drop in power in the aerodynamic position, especially if they are new to it, but if that drop is too large, then switching to a tri bike might not be your fastest option.
  • You're able to climb in the aero position on the tri bike. Not for the steeper gradients, but if you're unable to stay in the aero position for false flats and lower gradients, it will reduce the benefit of switching to a tri bike.
  • You're able to eat/drink as effectively on the tri bike as you can on the road bike.
  • Your running is not negatively impacted by your aerodynamic position.

If any of the above are not true, then it becomes a lot murkier.

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    You're able to climb in the aero position on the tri bike. at climbing speed, aero position is useless, especially if due to the position you lose some efficency in expressing your power
    – EarlGrey
    Dec 23, 2022 at 9:26
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    @LamarLatrell - correct, the aero position provides speed gains despite potential loss in power. You can have some loss in power and have the aero gains outweigh the loss, but there's a point where the power loss outweighs the aero gains. But where that point is depends so much on the individual fit that I can't say, "you must be within X% of the power on your road bike", but rather, "be roughly in the same ballpark power-wise." I will clarify that point in my answer.
    – Ealhmund
    Dec 23, 2022 at 11:15
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    @EarlGrey - at climbing speed, aero position is useless That entirely depends on what your climbing speed is. At steeper gradients, sure, the speed will be such that the aero benefits aren't worth it, but for more gradual gradients, the aero benefits still matter. It's dependent on the rider.
    – Ealhmund
    Dec 23, 2022 at 11:25
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    @EarlGrey - you don't have to be a professional cyclist for your climbing speed to be fast enough for aerodynamics to matter; which is a fact that calculator demonstrates. But in terms of answering the OP's question, if you aren't able to climb in the aero position on a hilly course like Ironman Nice, then it makes the specific question, "will a tri bike be faster" less clear cut.
    – Ealhmund
    Dec 23, 2022 at 13:21
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    @EarlGrey - Apples & oranges. Grand Tours are mass start events; drafting is legal. The GC guys have to use the spots where drafting is minimized to build a lead, which is why the mountaintop finishes and the time trials are so important to GC. But Ironman is not draft legal. Weak on climbs, you're losing time. Weak on the flats, you're losing time. Weak on descents, you're losing time. You can't draft, so all of it matters. You might be spending more time climbing, but if you can save time on some climbs via aerodynamics...why wouldn't you?
    – Ealhmund
    Dec 23, 2022 at 14:45
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Triathlon-specific bicycles are generally significantly more aerodynamic than UCI-legal road bicycles. They're specifically designed to be aerodynamic and sacrifice controllability, maneuverability, and comfort all to improve aerodynamics.

And since most everyone else in the race will be riding one, the cut-off time is based on that.

So if you don't ride one, in any serious race you'd be at a huge disadvantage.

How much faster will one make you?

That depends on how strong you are. The stronger you are, the more of a speed advantage a triathlon bike will give you because the absolute improvement in speed will be proportional to your speed without the aerodynamic advantage of a tri bike. 10% faster than "slow" is probably still something like "slow - just not as slow" (I might resemble that....), while 10% faster than "fast" might very well be "screaming fast".

It's hard to quantify the exact improvement you'd see, but using defaults on http://bikecalculator.com/ and setting power to 250 watts, the difference between "hoods" and "aerobars" is 6 kph. At 250W, the default "hoods" data estimates speed to be 34.5 kph. On "aerobars", it's 40.5 kph. Going from 34.5 kph to 40.5 kph is an improvement of 17%. That's huge.

And having ridden a TT bike, that 17% improvement in speed is not an inaccurate value. The actual improvement will depend on specifics (and likely won't be 17%), as others have mentioned. How aerodynamic is your "aero" position? Will you be able to sustain the same power when in that aero position? How well will you be able to climb? But values such as 8% faster or even 12% faster could even be called reasonable.

However, read this: A Case Against TT Bikes

Triathlon bikes (the TT or time trial bikes in the article are nothing more than UCI-legal triathlon bikes) can be dangerous - they've sacrificed everything for aerodynamics and speed.

Will you be able to control that bike at speed? If you're not comfortable hammering away close to your limit for literally a few hours, then the bike might not make you faster at all. It's really hard to ride as hard and as fast as you can when you feel like you're on the verge of losing control and plowing into the nearest tree at 40 kph or crossing the road centerline into oncoming traffic.

So if you do decide you want one, you need to ride it a lot to get comfortable riding it hard for a few hours. And please do not ride your triathlon bike in group rides - they are downright dangerous to everyone in the group. There are good reasons UCI has banned them from mass-start races.

And don't ever be that utter fool "try-athlete" on the local MUP and weave through kids and dogs and crowds at speed while on your aerobars.

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  • Is it relevant that tri-bikes can be also lighter than the UCI-legal road bikes?
    – EarlGrey
    Dec 23, 2022 at 16:17
  • @EarlGrey Not in a triathlon - UCI rules don't apply. A road bike that needs to have weight added to be UCI legal is likely to be lighter than a tri bike under the same non-UCI rules. Although FWIW I've never seen a bike weighed in any event. Maybe they do at upper pro levels, though?
    – Andrew Henle
    Dec 23, 2022 at 18:18
  • The case against TT bikes was not an article I agreed with in general, but it would definitely affect the OP on descents. And I see some significant ones here. The more technical the descent, the more you would favor the road bike.
    – Weiwen Ng
    Dec 23, 2022 at 20:07
  • @AndrewHenle I mean: a tri-bike may have an huge advantage, i.e. being much lighter than a road bike compliant with UCI rules.
    – EarlGrey
    Dec 23, 2022 at 22:38
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A tri bike would help, but it might not offer the best bang for your buck. Your body has a bigger aerodynamic impact than your bike, and putting it in an aero position, with aero bars, delivers a lot of the benefit of a dedicated tri bike. Aerodynamic wheels (low spoke counts, deep-section rims) would also make a big difference. Your helmet is another place where you get a lot of bang for your buck, and if you're wearing any clothes that flap in the wind, that's an easy thing to fix.

This course is hilly enough to negate some of aero benefits compared to a flat course. When you're climbing, you're going slow(er), and aerodynamics are less of an issue (because aerodynamic drag scales with the square of your speed). When you're descending, your ability to control the bike and your intestinal fortitude limit your speed more than aerodynamics do (I don't like descending on aerobars above ~50 kph).

One of the other features of a dedicated tri bike is an extremely forward saddle position. My understanding is that this is done to keep your legs fresher for the run. There are special seatposts you can put on a conventional road bike to achieve this position, but it looks like your bike uses a non-standard seatpost.

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    Good points about alternative methods of improving aerodynamics. I'll add one specific to racing: when you pin on your number, make sure it's flat against you and doesn't catch any air. I've seen way too many riders who pay $5000 for an aero racing bike, another $2500 for the most aero wheels, aero helmets, and skinsuits give it all back with a loose pinned-on number mini-parachute sucking 30W of power or more at race speeds. At the other end of the spectrum, I've seen a handful of racers cover the back of their pin-on number with spray-on adhesive to make sure it lies flat.
    – Andrew Henle
    Dec 23, 2022 at 11:55
  • There's a good video here by Aerocoach showing just how far you can take a road bike with clip-on aerobars: youtube.com/watch?v=_8eR0dFeJ0g The final CdA of 0.2093 m^2 is very good, probably on-par if not surpassing many pro triathletes.
    – Andrew
    Dec 24, 2022 at 1:58
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Depends on:

  • speed and wind conditions
  • closely related: elevation profile
  • your weight (for a 100kg cyclist a 1kg heavier bike has less of a negative impact than for a 60kg cyclist. But it’s tricky because the lighter rider will probably also have worse frontal area to power ratio.)
  • how much less drag you’ll actually have on a tri bike
  • if you can produce the same power output on a tri bike
  • if there are fast downhill sections, can you control the tri bike confidently enough to ride them at the same speed as the road bike (or even faster)?

If you use the same wheelset, same clothing etc. the main difference between a triathlon bike and an “aero” road bike is really the seating position and handlebar (and handling). A big question is if you can actually utilize the triathlon position.

Thanks to hydraulic brakes and electronic shifting even somewhat sharp turns and quick changes in steepness are okay on a modern triathlon bike. So it’s really not an easy answer.

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As covered in some other answers, a time trial bike becomes more beneficial as the athlete gets stronger and more skilled.

For an athlete that is in danger of missing the time cut, the benefit (if any) of a time trial bike is going to be very small.

First and foremost, for a successful Ironman you need great aerobic conditioning and a solid nutrition strategy (nutrition is often referred to as the 4th discipline of Ironman).

If I was an athlete looking to beat the time cut, there are several things i would invest time and money into before a Tri bike (especially on a hilly course).

  • Ensure consistent training with appropriate volume to build aerobic condition
  • Get a power meter and learn how to use it in both training and racing
  • Work on your nutrition strategy in training so you can ride strongly for the full distance.
  • Make sure you are using appropriate tyres. You could be throwing away 10-20W in rolling resistance.
  • Make sure you have appropriate clothing for the bike. An aero helmet and well fitting tri suit probably give more performance gain than a change of bike would.
  • Your swim will factor into making the bike cut off. Swimming is quite technical and some coaching can help you swim faster for less energy.
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  • The slower you go, the more time you save for a given CdA decrease, due to air drag being proportional to v^2. So in a sense, a triathlon bike becomes less beneficial as the athlete gets stronger. And the best cheap upgrade one can do (quite possibly a bigger time decrease than getting fitter) is to simply add clip-on aerobars, which will get you most of the way to a triathlon bike. Clip-on aerobars or a triathlon bike are worth much more than an aero helmet or skinsuit: youtube.com/watch?v=_8eR0dFeJ0g
    – Andrew
    Dec 24, 2022 at 17:19
  • @Andrew It's not always easy to fit clip on bars to modern bikes due to modern aero handlebars so i didnt include them in my answer. But yes, if they fit they are a great cost effective compromise - especially on a hilly course.
    – Andy P
    Dec 24, 2022 at 20:44

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