Autumn Transition Brick: Bike Into Run With Layering Practice

Session Overview

As daylight shortens and mornings cool into autumn, this brick session practises the layering decisions that catch a lot of triathletes out early in the season: what to wear on the bike leg without overheating, and how to shed or adjust it fast in transition before the run. It’s for anyone racing or training through the September-October shoulder season where a 6am start can be 8°C and a midday finish 18°C.

What You’ll Need

• Bike, turbo trainer or outdoor route with a safe, quiet transition point
• Base layer, arm warmers or a lightweight gilet — whatever you’d realistically race or train in this time of year
• Running shoes and kit staged as if for a real T2
• Optional: a stopwatch or phone timer to track your transition time

Warm-Up (10 minutes)

10 minutes easy spinning on the bike in your full cold-start layers, gradually building effort. Notice how quickly you warm up — this tells you how much you’ll want to shed later.

Main Set

The session alternates a longer bike block with a short run, forcing a real layering decision at the transition rather than just riding indoors in shorts and a jersey.

• Bike block: 40 minutes at steady zone 2-3 effort, arm warmers or gilet on for the first 20 minutes, then remove one layer on the move (or at a safe stop) for the second 20 — get comfortable adjusting kit without losing much time or effort.
• Transition: practise a full T2 — helmet off, shoes changed, layering decision made for the run (do you need the gilet again, or has the effort warmed you enough to run in just a base layer?). Time it.
• Run block: 20 minutes easy-to-steady off the bike, paying attention to whether your layering choice was right — too hot in the first mile usually means you overdressed for T2.

Cool-Down (10 minutes)

Easy walk or jog, then change out of damp kit quickly — autumn’s biggest risk isn’t the session itself, it’s standing around afterwards in sweat-soaked layers as the temperature drops.

Coaching Notes

• Practise removing arm warmers and gilets one-handed while still pedalling at low effort — it’s a genuinely useful race-day skill, but only rehearse it somewhere safe, not in traffic.
• Common mistake: overdressing for the run because you were cold at the start of the bike leg. Base your T2 layering on how warm the bike leg made you feel, not how you felt at the very start.
• Scaling: beginners can skip the on-the-move layer removal and simply stop briefly; advanced athletes can extend the bike block to 60 minutes and add a short pickup in the final 5 minutes of the run.
• Target RPE 5-6/10 for the bike block, 5/10 for the run — this is a technique and logistics session, not a fitness-testing one.