In training terms, what are 'junk miles' on the bike?

In training terms, what are 'junk miles' on the bike?

Let’s kick off the new year with plenty of controversy! Everyone’s writing up their training plans and registering for the year’s events. A lot of cyclists will also be setting a yearly mileage goal. Shooting simply for miles, though, isn’t a great choice. You might just be setting yourself up for a lot of junk miles.

Here’s where a large contingent pushes back, saying “no miles are junk miles.”

If the alternative to the junk mile is sitting on the couch, sure. If the alternative is structure training, no.

In the context of a structured training plan junk miles are those which prevent you from obtaining your goals:

Training Resources are Limited

Everyone has a genetic limit for how quickly they can recover and produce adaptations from training stress. If you attempt to add more training stress without allowing proper recovery, some combination of the following will befall you:

  • You’ll fail an interval or entire workout due to fatigue
  • You’ll struggle, but finish the workout but your body will be unable to adapt to the stress because it is overtrained
  • You fail or complete the workout and cause damage to your body, be it musculus-skeletal or your immune system

All Training Stress is Not Created Equal

Apps give single numbers to give us an idea of training stress, be it Strava or TrainingPeaks. Distilling a workout into a single number can lead to some very false conclusions. The following rides are all 100 TSS (training stress score):

  • 1 Hour at FTP
  • 2 Hours at 50% FTP

Those are two very different rides which will trigger very different adaptations.

Training methodologies are universally based on the longstanding belief that you increase them through “pushing” (long workouts below CP / LT) or “pulling” (short workouts above CP / LT). Additionally, it is believed that workouts at CP/LT are less successful at creating adaptation and thus raising CP/LT.

You Need to Train with Purpose

It’s entirely possible that one rider’s junk miles are another rider’s bread and butter, depending on their fitness and goals. If you want to train and improve with purpose, you need to first know what you’re training for. Training for a TT is a lot different than training for a crit which are both worlds away from training for a long gravel grinder or fondo.

When I think junk mile, I think overly hard endurance riding, ‘noodling’ endurance rides that are far too easy or ‘kitchen sink rides’ that attempt to jam every intensity into a single workout. Each can be a lot of fun, each can waste a lot of time and wear you out.

Junk miles are attractive because it feels like you’re working out while doing whatever feels comfortable. For intermediate and advanced riders to advance though, you have to think about how each week, if not each ride, fits into the progression toward chosen goals.

Sprinkling junk miles into a well thought out training plan can work and has the benefit of making training mentally acceptable, but watch that the majority of your miles are quality work prepping you for the start line.