Is a triathlon bike or a road bike better for descending?

A group of male and female cyclists in winter bike kit tackling some mountainous terrain — (Credit: Getty Images)

The triathlon bikes have the aero advantage but road bikes have superior handling, so which is better for descending?

In a flat or undulating triathlon, it’s obvious you should ride your dedicated triathlon bike, if have one.

But what about when there is more elevation gain and loss ? At what point does the pendulum swing in favour of a road bike’s lower weight on the climbs and better manouevrability on the downhills?

To try and answer this question, you have to factor in a number of variables. From the character of the descent to your cornering ability, let’s run through them.

Why you should choose a road bike to descend hills

GB triathlete Kate Waugh leads a bike breakaway that helped her win the 2022 U23 world title in Abu Dhabi — A road bike may be a better option for tricky descents (Credit: Janos Schmidt/World Triathlon)

The first is the technicality of the descent. If it consists of a sinuous series of switchbacks, such as Alpe d’Huez, or is steep and poorly surfaced, such as you’d encounter in the Lake District, a road bike will undoubtedly have the edge.

This is because road bike’s handling will be more responsive. You’ll be thankful for this if you have to make a quick adjustment in a corner.

You may find you can plunge downhill with more confidence, and therefore, faster on a road bike on a technically challenging descent.

Differences in geometry mean that on a road bike your weight will be further back than on a triathlon, which can help rear-wheel grip.

Tyres also have a big influence on descending speed.

You may be able to run wider tyres, which will be grippier, on your road bike thanks to more generous tyre clearance. On a rough, slippery descent, narrower triathlon bike tyres might slow you down.

A winding descent will also limit opportunities to use the extensions on the TT bike, diminishing its aero edge.

By contrast, you can adopt an aero tuck on a road bike to substantially reduce drag and increase speed while keeping the brakes close to hand.

The aerodynamic performance of road bikes varies a lot too. An aero road bike with deep-section wheels and narrow, aero handlebars will be much faster downhill than a rounder-tubed climbing bike, for example.

Why you should choose a TT bike to descend hills

NICE, FRANCE - SEPTEMBER 10: Leon Chavalier of France competes in the bike leg during the 2023 Men's VinFast IRONMAN World Championship, on September 10, 2023 in Nice, France — On wide, open descents a triathlon bike will be fastest (Credit: Jan Hetfleisch/Getty Images for IRONMAN)

However, if it’s non-technical, not very steep and you’ve got the nerve to stay down on your extensions, you’ll fly on your TT bike. It doesn’t take much time down on the extensions to claw back time losses due to inferior handling.

Next is the skill of the rider. If you’ve spent hours training on your TT bike, ridden technical roads and are 100% familiar with how it handles, you won’t be at any significant disadvantage descending on it.

However, if you’re one of those triathletes who only rides their TT set-up on race day and on the turbo, you’ll be shipping seconds on every downhill.

Finally, there’s the bike’s set-up. If your TT bike is equipped with disc brakes, that’ll go some way to off-setting time losses due to handling.

Satellite shifters on the bull-horns will also help significantly on descents, allowing far better shifting in and out of corners than extension shifters only.

Aero clothing and accesories

Met Manta MIPS aero road helmet — A good aero helmet should help you bomb downhill quicker (Credit: Rob Slade)

Bike choice and technique aren’t the only factors affecting your downhill speed.

More aerodynamic clothing and equipment, such as the best tri suits and the best aero helmets, could save you watts and up your speed whichever type of bike you’re riding.

About

Nikalas Cook is a writer, author, coach and athlete based in the Peak District. He specialises in health, fitness, endurance and adventure sports. Having studied a postgraduate degree in Health and Exercise Science, he worked for eight years as a top personal trainer in London. He was the editor of Totally Active magazine and writes for numerous specialist magazines and websites including 220 Triathlon, Outdoors Magic, Trail Running and Trek and Mountain. He has also edited the British Cycling member’s website, the Insight Zone. He’s written for national newspapers and magazines including The Times, The Financial Times, The Daily Mail, GQ, Men’s Fitness and Red Magazine. But he’s probably most proud of being Derbyshire Life’s beer correspondent. Nik has written two books (Marathon Training: Get to the Start Line Strong and Injury-free; Peak District Trail Running: 22 off-Road Routes for Trail & Fell Runners) and his third, entitled The Road Cycling Performance Manual, was published by Bloomsbury in June 2018. He has also worked with Nigel Mitchell on his book, Fuelling the Cycling Revolution, and with Martin Evans and Phil Burt on their book, Strength and Conditioning for Cyclists. He’s completed numerous cycling challenges including the Trans-Wales MTB stage race, the Fred Whitton, the Raid Pyrenees and both the Paris-Roubaix and Tour of Flanders sportives. Competitively, he likes to combine his cycling with running and has previously won gold in his age-group at the ITU World Long Course Duathlon Championships at Powerman Zofingen.