'No-Training' Speed Gains On The Bike

We are often asked by athletes directly or via Facebook questions on whether it's worth investing in bike options to make the bike leg faster, nearly always asking about bike fit, and if there's a budget, what to buy first. Here is our answer, based on 15 years of racing and coaching multisport and single sport bikers, wind tunnel testing and scientific papers condensed here into an easy guide into watts saved over what distance Sometimes the smallest detail matters; 3 years ago we saw a female Age Grouper in a local wind tunnel save 11, 10 and 12 watts simply by tucking her pony tail up into a chignon (think 'donut' for those that don't know) and fastening it under her helmet, for those without pony tails, and those with, here's the skinny on being a faster biker

We'll look at the actual CdA (Coefficient of Drag × frontal Area) figures of typical triathletes in the next blog and what it means for power output and pacing but for the meantime we'll keep it simple. CdA is the single best metric summarising aerodynamic efficiency on the bike. Lower CdA = less drag = more speed for the same power

Below is a realistic hierarchy of the main aerodynamic gains based on wind-tunnel studies, pro fit data, and field testing. The key insight: the rider creates ~75–85% of total drag, so position dominates everything

Assumptions for time savings:

• athlete riding ~35 km/h Olympic pace equivalent

• moderately aero baseline setup

• flat to rolling course

• improvements compared to typical age-group setup (not extreme worst case)

  
  

Bike Aero Position (illegal in World Triathlon & UCI)

Two things to point out, MORE time can actually be saved for a novice moving to these changes and actual savings vary with speed (faster riders gain more seconds per watt saved).

Also bear in mind that much of the time savings and percentages saved over a road bike without aero options quoted in many academic papers and wheel / tyre brands are based on very good cyclists or pros, in great conditions or wind tunnel and usually at or above 40KPH, for the more 'average' biker these numbers are figures to aim for only! Some kit or equipment additions really should be combined together if the athlete can afford it as the sum of the parts is higher than individual contributions

Aerodynamic Impact Ranking (Most → Least Important)

Assumes typical age-group baseline vs optimised setup at ~35 km/h equivalent effort.

1. Position dwarfs equipment

Factor	Why it matters	Typical watts saved	Sprint	Olympic	70.3	Ironman
Body position	biggest CdA reduction	30–90W	40–75 sec	1.5–3 min	4–7 min	8–14 min

A well-fitted athlete on a mid-range bike often beats a poorly positioned rider on a superbike

Typical improvements:

• narrower arm pads

• flatter back

• stable head position

• reduced frontal area

  
  

Even small posture changes can produce measurable gains

Cost - anything from free in the mirror or with an app or gosh-forbid feedback from a Facebook forum (advice always to raise the saddle) to upwards of $/€/£250 with a good bike fitter. This does not include any 'parts' necessary to make the adjustments

2. Aero bars unlock the rest of the gains

Factor	Why it matters	Typical watts saved	Sprint	Olympic	70.3	Ironman
Aero bars	enables narrow frontal area	15–40W	20–40 sec	1–2 min	2.5–4 min	5–8 min

Clip-on aero bars:

• reduce frontal width

• encourage forward pelvic rotation

• allow sustainable narrow arm position

  
  

Without them, helmet and clothing gains are limited.

Cost - anything from $/€/£30-40 second hand ( ensure the clasp fits your shape and size of handlebar) to high 600s for some full carbon bars. We are not talking integrated tri bars like you'd find on a dedicated TT / Tri bike with it's risers, stem choices, changeable angles of attack, arm rests and integrated gears and sometimes brakes

3. Aero helmets are consistently strong value

An Aero branded Aero Helmet

Factor	Why it matters	Typical watts saved	Sprint	Olympic	70.3	Ironman
Helmet	smooth airflow head/back	8–25W	10–25 sec	30–75 sec	1.5–3 min	3–5 min

Compared to standard road helmets:

• smoother airflow behind head

• especially beneficial in steady TT position
  

Often one of the cheapest watts saved per $/€/£. By definition these helmets have less ventilation and so heat up, choose lighter colours for marginal comfort improvements. If you are racing in warmer climes is it worth the discomfort and maybe neck / back position / restricted integrated visor air flow for the minutes or seconds it may save you?

Cost - anything from $/€/£99 to 300 for an aero lid, don't buy second hand, and remember depending on the MIPs / Protection system / materials used one of these helmets might have a manufacturer life span of 2-4 years. Personally I use a non aero specific Giro Aries with it's 24 vents to keep cool on ALL courses as I priortise comfort and heat dissipation above all else

4. Clothing is underestimated

Factor	Why it matters	Typical watts saved	Sprint	Olympic	70.3	Ironman
Clothing / trisuit	reduces turbulent drag	8–20W	10–20 sec	30–60 sec	1–2.5 min	2–4 min

Loose kit creates turbulence

Modern trisuits use:

• textured fabrics

• seam placement to reduce drag

• compressive fit

Wrinkles alone can cost measurable watts

Cost - anything from $/€/£99 to 300+ for top of the range tri suits from Castelli or ROKA that feature separate shorts and shirt, dimpled fabric arms for faster air flow and integrated SFP protection up to 50. Many cheaper suits will give most of the same savings at a better price point

5. Wheels help — but not as much as marketing suggests

Factor	Why it matters	Typical watts saved	Sprint	Olympic	70.3	Ironman
Wheel depth	improves airflow stability	5–20W	10–20 sec	30–60 sec	1–2 min	2–3 min

Deep wheels help maintain airflow attachment in crosswinds. There are many options plus a recent trend of mixing rim depths front and rear to 'optimise' aero benefits. Many aero wheels come with different spoke lacing patterns, raised flanges or lips / protections around the hub to aid air flow, 'bladed' spokes but the most significant development has been (brand led collaborations) tyre choices mated to wheel to optimise tyre footprint and rolling resistance. Many bikes now have wider clearance for these effectively wider wheel and tyre combinations

Biggest benefit:

• sustained speeds above ~32 km/h, good wheel aerodynamics can create a 'sail effect'

• one thing to note, most wheel figures show benefits in optimum wind angles, many don't in real conditions when winds are from the sides or oblique
  

Disc rear wheel often adds stability and small speed gains on flat courses

Always go with brands that you know, check thoroughly second-hand wheels, does the owner present them clean, are they crash signs free, does the owner talk knowledgeably about bikes generally? I avoid 'knock off' and to be honest all cheap wheelsets from China, which is probably unfair, but I know that European brands usually conform to UCI regulations and are generally bomb proof. I don't want to be descending at 80kph and find the brake track delaminating under braking heat or the carbon fibre lay up of the wheel not up to my combination of weight and speed. You decide

Cost - wheelsets are anything from $/€/£250-450 (for cheaper carbon, maybe with aluminium brake tracks or pre owned to 3500+ for wheels from Lightweight Meilenstein or Enve amongst others. The choice is vast, I ride Enve 60s, (60mm rim depth) as they are suitable for road and tri bike racing / speed especially on hilly courses and a pair of aero-optimised climbing wheels from Enve too. For everyday kudos I ride the British brand Hunt wheels coming in at around £650; ask any owner, you can't beat that characteristic whirring -buzz as you freewheel behind slower bikes! For rim brake wheels there are some great bargains too out there

6. Tyre Width - Counterintuitive Truth

Factor	Why it matters	Typical watts saved	Sprint	Olympic	70.3	Ironman
Tyre width + model	affects airflow + rolling resistance	4–15W	5–15 sec	20–45 sec	1–2 min	2–3 min

Wider is faster

Modern findings:

• 25–28 mm tyres often outperform 21–23 mm• reduced vibration losses = lower rolling resistance• improved airflow when tyre matches rim profile. There is a big movement to 32mm tyres now, even on the pro tour

The reason, the tyre deforms less in contact with the road and has a bigger contact patch, so it rolls more in the 'proper' shape than a slimmer tyre profile. Very often more comfortable. A big difference too is the compound used in the tyre, a Winter Continental brand tyre will be optimised against punctures with a vectran lining, be a bit heavier and it's compound will work best to stick you to the road in colder conditions, together with a minimal tread pattern, it won't be the fastest in the summer and it can be a bind to get off the wheel Faster tyres for racing offer less roadside debris puncture protection. I use the fast versions of the Schwalbe One, Vittoria Corsa and my go-to favourite for general and specific 'fast' the Pirelli P Zero tubeless set up, the same as my car. Tubeless also roll with less pressure so they're fast and comfortable

Google the Silca Professional Tyre Pressure Calculator online or on app. Plug in your brands, tyre width and size and it will offer the optimum tyre pressure for any tyre

Key concept:tyre should not bulge wider than rim

Example pairing:

• 28 mm tyre on 25 mm external rim → often optimal

• 23 mm tyre on wide rim → airflow separation

  
  

Vibration losses matter more in real-world road surfaces than perfect lab tarmac

Top tip💡Early season and after rain, stay away from kerbs and gutters, especially if you live in the country - brambles, hawthornes and general hedge cutting do not make happy bed fellows to thin fast moving rubber. Rain tends to wash road debris to the gutter of course

Factor	Why it matters	Typical watts saved	Sprint	Olympic	70.3	Ironman
Tyre Compound	mainly rolling resistance	2–8W	3–8 sec	10–20 sec	30–60 sec	1–1.5 min

Cost - see tyre types

7. Bottle placement can add or reduce drag

Factor	Why it matters	Typical watts saved	Sprint	Olympic	70.3	Ironman
Bottle placement	can disrupt airflow	3–10W	5–10 sec	15–30 sec	40–80 sec	1–2 min

Generally favourable:

• between arms (BTA bottle)

• integrated frame bottles

• Aero shaped (thin or angular bottles) idea for TT's and shorter races, contain less volume

• and with practice, bottles located behind saddle, not liked by groups especially if your bike maintenance is less than regular
  

Often unfavourable:

• round bottle on down tube (depending on frame)

• multiple bottles disrupting airflow

• stuffed down front of shirt in licensed races, now banned

• home built rigs that have a long tube / straw from the bike mounted water bottle, my favourite and oft used race hack, now frowned upon in the rules

Cost - from $/€/£4-7 up to multiples of that for a branded version, add carbon bottle cages or attachments then expect another 50-70

Below, you'll find data from Aerocoach's water bottle testing, which illustrates the drag penalties incurred at a speed of 40 kilometers per hour, which is a really high benchmark for all but the super fit and trained podium level athletes

• Downtube 900 ml bottle = 8.2 watt penalty, 3:20 in Ironman

• Seat tube 900 ml bottle = 5.7 watt penalty, 2:30 in Ironman

• Saddle 900 ml bottle = 2.5 watt penalty, 1:05 in Ironman

• Between The Arms =1.2 watt penalty with 500 ml, 30 sec in Ironman
  

8. Tubeless vs Clincher vs Tubulars

Tubeless (fastest overall for most triathletes)

Pros:

• low rolling resistance

• puncture protection via sealant (seals pretty quickly any smaller punctures, nicks and holes that would stop you on a regular clincher or tubeless

• lower pressure possible

• improved comfort → less fatigue

• becoming common from 'new school'

  
  

Cons:

• setup complexity

• extras required, sealant, tubeless valves, spinning around to get sealant distribution, topping up of sealant every 3 months

• many bikers carry a latex inner too or fit one as extra security in case a rip or puncture can't be sealed. A boot is a small bit of rubber that adheres chemically to the tyre in case of a big rip, but if you're prone to disasters of this scale then maybe road biking should be swapped for off road or MTB!

  
  

Biggest benefit, most small punctures self seal enough to get you home with sufficient pressure if you're careful. Or if you have a plug repair kit like the brilliant dynaracer, (cheaper ones available) then it's literally less than 30 secs to locate the hole, insert a rubber bonding plug that seals the tyre permanantly and whose protruding bit gets ground down as the wheel rotates as you continue your ride. I ride longer rides with the dynaplug (size of a fat biro and a small Fumpa Pumpa (auto inflater) which is around 8x10cms and does around 3-5 inflations. If you're racing or in a hurry then the benefits alone with a tubeless set up pay for the costs, if you dont mind getting the occasional shower of sealant up your legs! Typical gain vs standard butyl clincher: 3–8 watts

Clincher with latex inner tube

Often nearly as fast as tubeless, becoming a little 'old school' although the type has a vast following amongst racers and the general bike buying public

Latex tubes:

• lower rolling resistance than butyl

• lightweight

• cheaper upgrade

  
  

Downside:can lose air overnight and depending on tyre brand, The Continental Gators used to defeat me in roadside emergencies, any type of tyre lever, GB mechanics and my thumbs just couldn't change. If you ride in a group there's always someone who is good though at changing tyres for you, just don't rely on them, you'll soon wonder why you're riding alone unless you get some absolutely necessary skills in this area

Tubular (less common now)

Historically fastest in pro peloton. Think a sausage adhered with glue to your wheel rim. I still have one set up with these, my Enves, fast and smooth. If you're going to race with them then you need to carry rim tape and a whole spare tyre folded over and carried in some way on your bike if the puncture is a big one, not ideal for modern racing or triathlon

Advantages:

• very light

• good ride feel

  
  

Disadvantages:

• difficult roadside repair

• modern tubeless often equal or faster

• Usually prohibitively expensive individually and as ideally you need to buy matching rubber
  

Cost - from $/€/£45-90 each on average for less faster compound tyres / slower tyres to quicker versions but you can pay up into the hundred + for top of the range race specific tyres

Optimal Tyre Setup for Most Triathletes

Typical fast configuration:

25–28 mm tyre• high-quality tubeless or latex tube• pressure adjusted to rider weight and road surface• matched to rim width. Compared with:23 mm training tyre + butyl tube

Potential savings:

Sprint: ~10–20 secOlympic: ~30–60 sec70.3: ~1–2 minIronman: ~2–4 min

Marginal Gains Priority

1. body position

2. aero bars

3. helmet

4. trisuit

5. tyre choice + pressure

6. wheels
   

Tyres often beat expensive wheel upgrades in cost-effectiveness. A typical age-group athlete upgrading smartly might gain without increasing fitness:

• 6–10 min in Ironman • 3–5 min in 70.3 • 1–2 min Olympic • 30–60 sec Sprint