CoachingAnswer

WHAT ARE JUNK MILES IN CYCLING?

By Anthony WalshRoadman CyclingUpdated 9 July 2026

ANSWER

Junk miles are rides performed at a moderate intensity — typically Zone 3 or the grey zone — that is too hard to allow proper recovery but too easy to stimulate meaningful physiological adaptation. They accumulate fatigue without producing proportional fitness gains. Most amateur cyclists default to this intensity on every ride because it feels comfortably hard. The fix is polarised training: make easy rides easy (Zone 1-2) and hard rides hard (Zone 4-5), with minimal time in the grey zone between.

KEY TAKEAWAYS

Junk miles happen in Zone 3 — an intensity that feels productive but is neither easy enough for recovery nor hard enough for adaptation.
Most amateur cyclists spend 50-70% of their riding time in this grey zone, compared to elite athletes who spend 75-80% in Zone 1-2.
The fix is polarised intensity distribution: 80% of rides at Zone 1-2 (conversational pace) and 20% at Zone 4-5 (controlled discomfort to maximal).
Not all moderate riding is junk — tempo work has a specific place in periodised training plans, but it should be intentional, not the default for every ride.

WHO THIS IS FOR

IS THIS YOU?

Riders who train consistently but stop improving

You ride regularly and feel like you are working hard but your fitness has plateaued. You may be trapped in the grey zone without realising it.

Self-coached cyclists trying to structure training better

You have heard the term junk miles and want to understand what it means practically and how to avoid it in your training.

THE ROADMAN VIEW

Junk miles are the single biggest reason amateur cyclists plateau, and Anthony has made this point on the podcast more times than he can count. The problem is that riding at moderate intensity feels productive. You are breathing hard, you are sweating, your legs are working — surely that is training, right? Technically yes, but it is the least efficient form of training because it produces fatigue without targeted adaptation.

Here is the reality check: if every ride feels roughly the same level of effort — somewhere between 'this is fine' and 'this is uncomfortable but sustainable' — you are living in the grey zone. Your easy rides are too hard (so you never fully recover) and your hard rides are too easy (so you never push the physiological systems that produce real improvement). The fix sounds counterintuitive: ride slower on your easy days. Slow enough that it feels embarrassingly easy. Then, twice a week, ride properly hard. That polarisation is what produces results, and it is what virtually every elite endurance athlete does.

EXPERT EVIDENCE

WHAT THE EXPERTS SAY

Dr Stephen SeilerExercise physiologist, researcher in training intensity distribution
Across multiple sports and multiple decades of research, the pattern is consistent: the best endurance athletes spend 75-85% of their training time at low intensity (below the first ventilatory threshold) and 15-20% at high intensity (above the second ventilatory threshold). They spend remarkably little time in the moderate zone between. This polarised distribution produces the best long-term aerobic development while managing fatigue and injury risk.

PRACTICAL APPLICATION

DO THIS WEEK

Audit your training intensity distribution
Review the last 4 weeks of rides in your power or heart rate data. Calculate the percentage of time in Zone 1-2 (easy), Zone 3 (moderate), and Zone 4-5 (hard). If more than 30% of your time is in Zone 3, you likely have a junk miles problem. Target 80% Zone 1-2, 5-10% Zone 3, and 15-20% Zone 4-5.
Make easy rides easy
On recovery and base rides, set a heart rate ceiling (typically 75% of max HR or Zone 2 upper limit) and do not exceed it. If a hill pushes you above the ceiling, gear down or walk. It should feel easy enough that you could hold a full conversation. If riding partners push you above Zone 2, ride alone on easy days.
Structure two quality sessions per week with specific targets
Replace grey-zone rides with two structured sessions: one threshold workout (2x20 min at FTP) and one VO2max session (5x4 min at 106-120% FTP). These sessions produce far more adaptation per minute than moderate riding, and the hard effort is contained within specific intervals rather than spread across the whole ride.

COMMON MISTAKES

WHAT CYCLISTS GET WRONG

MISTAKEThinking that all moderate riding is wasted.
FIXIntentional tempo work (Zone 3, sweet spot) has a place in periodised training — it develops muscular endurance and race-specific fitness. The problem is when moderate intensity becomes the default for every ride. Planned tempo is training; unplanned moderate riding is junk.
MISTAKEMaking easy rides too hard because they feel unproductive.
FIXEasy rides are not wasted time — they promote recovery, build aerobic base, and prepare your body for the next hard session. The adaptation from easy rides is real but invisible in the moment. Trust the process and ride easy when the plan says easy.
MISTAKETrying to keep up with faster riders on designated easy days.
FIXGroup rides and Strava segments make it psychologically difficult to ride easy. On designated easy days, ride alone or with a slower group. Your ego takes a hit; your fitness does not.

FAQ

FREQUENTLY ASKED QUESTIONS

Is Zone 3 always junk?

No. Zone 3 (tempo) is a valid training zone when used intentionally within a periodised plan — for example, tempo blocks in the base phase or sweet-spot sessions in the build phase. It becomes junk only when it is the unintentional default intensity for most of your riding, replacing both easy recovery and hard stimulus.

How do I know if I am riding in the grey zone?

The simplest test: can you hold a conversation? If yes, you are in Zone 1-2 (good for easy days). If you cannot speak at all, you are in Zone 4-5 (good for hard days). If you can speak in short sentences but it is uncomfortable, you are in Zone 3 — the grey zone. On easy days, you should be able to chat continuously.

Do professional cyclists avoid Zone 3?

Professional cyclists spend 75-85% of their enormous training volume at Zone 1-2 and only 15-20% at high intensity. Their Zone 3 time is surprisingly low — typically under 10% of total volume. They ride easy days truly easy (even at 200 watts, which would be threshold for most amateurs) and hard days brutally hard.