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LATE BASE · 12 WEEKS OUT

LEADVILLE TRAIL 100 — 12 WEEKS OUT

Bridge phase. Volume still rules, but structure begins. Built around the 160km / 3,800m profile of the Leadville 100 in USA.

160 km·3,800 m climbing·8-12 hours·August

THE FOCUS RIGHT NOW

BUILD THE ENGINE.

Twelve weeks out, you're still building the base — but specific structure is starting to appear. Tempo work enters the picture one day a week. Long rides get longer. This is where the event-specific fitness starts to take shape without compromising your aerobic foundation.

THIS WEEK'S ANCHOR SESSION

TEMPO SANDWICH

2x20min at tempo (76-88% FTP) inside a 2-hour Z2 ride. Steady, controlled, not a time trial. This is your first taste of extended race-pace efforts.

THE WEEK

A TYPICAL WEEK, 12 WEEKS OUT

Monday

REST

Non-negotiable.

Tuesday

TEMPO SANDWICH (2H)

2x20min tempo inside steady Z2.

Wednesday

STRENGTH + 1H RECOVERY SPIN

Keep the gym work periodised.

Thursday

2H Z2 WITH 4X8MIN TEMPO

Progressive tempo work.

Friday

REST OR EASY 30MIN

Protect the weekend.

Saturday

4-5H LONG RIDE WITH EVENT-SPECIFIC TERRAIN

Mimic your target event's profile.

Sunday

2H Z2 RECOVERY RIDE

Active recovery, conversational pace.

DON'T DO THIS

Don't start threshold intervals yet. The build phase will come. If you jump intensity too early you'll peak 6 weeks before race day and arrive flat.

EVENT INTEL

WHAT THE LEADVILLE 100 ACTUALLY DEMANDS

Leadville 100 is the definitive high-altitude MTB race — 160km through the Colorado Rockies starting at 3,100m (10,200ft) with 3,800m of climbing and a topout above 3,800m on Columbine Mine. Lottery entry, hard cut-offs, finisher buckle is a career milestone.

KEY CHARACTERISTICS

  • ✓Altitude 3,100-3,840m — altitude-naive riders lose 20-30% power
  • ✓Columbine Mine climb — 9km straight up to 3,840m above sea level
  • ✓Cut-off at the Columbine turnaround (6:00) is the race
  • ✓Powerline descent — fast, rocky, tyre-popping territory
  • ✓Weather varies from freezing dawn to 30°C + thunderstorms

COMMON MISTAKES

  • ✕Arriving less than 2 weeks before for altitude acclimatisation
  • ✕Racing the first 40km on paved road sections and blowing up at altitude
  • ✕Running tyres too light — Leadville's rocks destroy XC casings

PACING

Altitude changes everything. Target a power ceiling 15-20% below what you'd hold at sea level. Heart rate runs 5-10 bpm higher than your lowland rate at the same effort — don't panic. Columbine Mine is a controlled climb at aerobic threshold. The flats + the Powerline descent are where the front group makes time; the back half is where you win your sub-9 buckle.

FUELLING

Altitude suppresses appetite — force-fuel on a timer. 70-90g carbs/hour. Feed zones are excellent (crew + on-course). Hydration is critical: 750ml+/hour with electrolytes. The dry Colorado air dehydrates faster than you feel.

KIT

Hardtail or 120mm trail bike. 2.3-2.4" tyres with Enduro or MaxxTerra casings — not XC race tyres. CO2 + pump + plug kit + spare tube. Arm warmers + gilet for the 06:30 start (cold). Altitude requires sunglasses with good UV + clear lens backup for the Columbine descent (often cloud + rain).

WANT THIS BUILT AROUND YOUR FTP?

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FAQ

COMMON QUESTIONS AT 12 WEEKS OUT

Is 12 weeks enough to train for the Leadville Trail 100?+

Yes, 12 weeks is a strong window. That's enough time for a full base phase, build, peak, and taper — the classical periodisation structure. 3,800m of climbing over 160km is built with sustained Z2 volume (base) + threshold work (build) in that order.

What's the hardest part of the Leadville Trail 100?+

Altitude 3,100-3,840m — altitude-naive riders lose 20-30% power. arriving less than 2 weeks before for altitude acclimatisation — so pacing discipline is the single biggest lever most amateurs miss. Altitude changes everything.

How many hours a week should I train at 12 weeks out from the Leadville Trail 100?+

Aim for 8-12 hours/week if you're targeting a strong finish. The long weekend ride is the anchor (3-4 hours at build intensities) plus 3-4 structured weekday sessions. Volume matters more than intensity at this phase.

Do I need a coach to train for the Leadville Trail 100?+

You don't need a coach to finish. You do need structure. If you're new to sportives, have a target finish time, have a plateau you can't break, or have a history of peaking wrong, a coached plan pays for itself. Inside Not Done Yet the plan is built backwards from your event date — base, build, peak, taper timed to the week the Leadville Trail 100 runs. 7-day free trial, $195/mo.

What gearing should I run for the Leadville Trail 100?+

Hardtail or 120mm trail bike. 2.3-2.4" tyres with Enduro or MaxxTerra casings — not XC race tyres. CO2 + pump + plug kit + spare tube. Arm warmers + gilet for the 06:30 start (cold). Altitude requires sunglasses with good UV + clear lens backup for the Columbine descent (often cloud + rain).

OTHER PHASES FOR THE LEADVILLE 100

Earlier phase ← 16 weeks out

BASE PHASE

Later phase → 8 weeks out

BUILD PHASE