Built for triathletes who refuse to leave watts on the bike leg. Same ribbed woven fabric developed for the One Aero Socks — the fabric that delivers 10.45 W savings at 45 km/h versus the previous sock generation — now extended to full mid-calf height with no UCI limit.

Model is 185cm with a calf circumference of 39cm wearing a size XL
Shop the Silhouette

Shop the Silhouette

One Triathlon Suit
One Triathlon Suit
Rule 28
£350
One Aero Calf Guards
One Aero Calf Guards
Rule 28
£40

Shop the Silhouette

One Triathlon Suit
One Triathlon Suit
Rule 28
£350
One Aero Calf Guards
One Aero Calf Guards
Rule 28
£40

Shop the Silhouette

One Triathlon Suit
One Triathlon Suit
Rule 28
£350
One Aero Calf Guards
One Aero Calf Guards
Rule 28
£40
Third-generation design. Fully woven construction drops 18 g per pair and adds another 2–3 W on top of the sock baseline.
No foot section — swim legal under the wetsuit, zero delay in T1.
Still the highest £-per-watt gain in triathlon equipment. By a distance.
Usage

Built for riders chasing elite aerodynamics in every scenario. Pairing wind-tunnel optimised panel layouts, state of the art R&D, and custom-made fabrics.  A package that provides World Tour-grade performance, ready to wearand race.

Wear it for high-velocity training, decisive efforts, and race days where optimal aero matters as much as power.

Surpassed in performance only by our Neo collection.

Technology

Aero

Lightweight woven fabric with custom spaced vertical ribs to turbulate aeroflow where needed producing excellent aero savings reduce drag.

Second Skin

Custom made, ultra-low skin friction fabric, made from very fine, high density fibres hides the body from the wind.

Composition & Care

Elastane 35% Poly 65%, 125GSM

Machine wash cold (30° max)

Do not bleach

Don not store damp

Do not tumble dry

Do not dry-clean

Warranty

All pieces carry a one-year manufacturing warranty from date of purchase. This covers defects in materials, workmanship, and construction faults. Thsi does not extend to normal wear and tear, or improper care. This warranty only applies only to purchases made directly through our site.

For any claim, reply to your order confirmation email or write to info@rule28.com with your order number and clear photos. We’ll handle it the same day.

Crash Replacement

If the worst happens and your kit is damaged beyond repair in a crash, send us clear photos of the damage along with your original order details.

We’ll sort a discounted replacement the same day we receive them. Like-for-like where possible.

This sits alongside the standard one-year manufacturing warranty and doesn’t cover normal wear or misuse.

Just email info@rule28.com — we’ve got your back when the road doesn’t.

One Aero Calf Guards

One Aero Calf Guards

£40 GBP
£40 GBP £40 GBP
Sale Sold out
Taxes included.
10.5 W saving
Color Black
Size Size Guide

Performance

Core Elite

Temperature

°C °F
-10 °C 0 °C 15 °C +30 °C
Brethability
4/5
Duration
5/5

Need Help?

Check out our FAQ first for answers.
Still need assistance?
Our support team is here to help.
Reach out through our contact form.

Shipping & Returns

Returns are accepted within 30 days of dispatch. Items must be unworn and in their original packaging.

View full details

Built for triathletes who refuse to leave watts on the bike leg. Same ribbed woven fabric developed for the One Aero Socks — the fabric that delivers 10.45 W savings at 45 km/h versus the previous sock generation — now extended to full mid-calf height with no UCI limit.

Model is 185cm with a calf circumference of 39cm wearing a size XL
Shop the Silhouette

Shop the Silhouette

One Triathlon Suit
One Triathlon Suit
Rule 28
£350
One Aero Calf Guards
One Aero Calf Guards
Rule 28
£40

Shop the Silhouette

One Triathlon Suit
One Triathlon Suit
Rule 28
£350
One Aero Calf Guards
One Aero Calf Guards
Rule 28
£40

Shop the Silhouette

One Triathlon Suit
One Triathlon Suit
Rule 28
£350
One Aero Calf Guards
One Aero Calf Guards
Rule 28
£40
Third-generation design. Fully woven construction drops 18 g per pair and adds another 2–3 W on top of the sock baseline.
No foot section — swim legal under the wetsuit, zero delay in T1.
Still the highest £-per-watt gain in triathlon equipment. By a distance.
Usage

Built for riders chasing elite aerodynamics in every scenario. Pairing wind-tunnel optimised panel layouts, state of the art R&D, and custom-made fabrics.  A package that provides World Tour-grade performance, ready to wearand race.

Wear it for high-velocity training, decisive efforts, and race days where optimal aero matters as much as power.

Surpassed in performance only by our Neo collection.

Technology

Aero

Lightweight woven fabric with custom spaced vertical ribs to turbulate aeroflow where needed producing excellent aero savings reduce drag.

Second Skin

Custom made, ultra-low skin friction fabric, made from very fine, high density fibres hides the body from the wind.

Composition & Care

Elastane 35% Poly 65%, 125GSM

Machine wash cold (30° max)

Do not bleach

Don not store damp

Do not tumble dry

Do not dry-clean

Warranty

All pieces carry a one-year manufacturing warranty from date of purchase. This covers defects in materials, workmanship, and construction faults. Thsi does not extend to normal wear and tear, or improper care. This warranty only applies only to purchases made directly through our site.

For any claim, reply to your order confirmation email or write to info@rule28.com with your order number and clear photos. We’ll handle it the same day.

Crash Replacement

If the worst happens and your kit is damaged beyond repair in a crash, send us clear photos of the damage along with your original order details.

We’ll sort a discounted replacement the same day we receive them. Like-for-like where possible.

This sits alongside the standard one-year manufacturing warranty and doesn’t cover normal wear or misuse.

Just email info@rule28.com — we’ve got your back when the road doesn’t.

Size Guide

Measure the circumference of your calves at the middle of the shin.

Your Body Measurements

Size Chart
Size
Calf (cm)
Calf (in)
S
>23
>9
M
23–31
9–12
L
32–38
13–15
XL
38<
15<

How to Get Your Measurements

1

Foot

We recommend choosing the same sock size as your shoe size. If your calf measurement falls outside the typical range for your shoe size, select the sock size that fits your calf instead
10.5 W saving
Over a flat Ironman bike leg (180 km), at 40 km/h, a saving of 10.5 W would save our test rider approximately 232 seconds compared to our previous calf guards. Put another way, as this rider crossed the line in the new suit, the same rider in our previous suit would be approximately 2,580 meters (or 8,465 feet) behind.
10.5 W saving