Jasper: 24 minutes faster at a favourite gran fondo
Jasper supports the event-specific side of SEMIPRO: the value is not just better test numbers, but being more durable when race day gets messy.
Cut 24 minutes from a favourite gran fondo

Result at a glance
- Main outcome
- 24-minute event personal best
- Timeframe
- Not stated
- Rider context
- Cyclist in his 50s preparing for a gran fondo
- Product used
- Coaching
Where this rider actually started.
Started riding in 2021 with a critical power under 200 W, riding raw miles with no plan — as he puts it, either way too hard or way too soft.
Coaching began in early 2024 at around 238 W, reaching 286 W that year before a break.
The 2025 build started again from 261 W.
Goal. Take 20 minutes off the previous year’s time, set a personal best on Palomar Mountain, and halve the gap to the age-group winner.
Main constraint. Started cycling in 2021, came back after a break in training, and had to build for a long mountainous event rather than for test numbers.
The decisions behind the result.
- Weeks 1–3: a threshold foundation block mixing over-unders with steady-state threshold. Durability elements entered in week 3 as efforts under fatigue plus one big aerobic day.
- Week 4: reload, with volume and intensity both cut in half.
- Weeks 5–6: a short taper into a nine-hour ride to test mental resilience, then maintained intensity and testing to set up the next block.
- Weeks 7–9: a full VO2max block built mostly on short efforts, while the durability work progressed through cadence work at fatigue and tempo at the end of rides.
- Week 10: rest week, with a VO2max fartlek left open to the rider.
- Weeks 11–13: peak and taper. Race-specific mixed efforts stacked to match what the event would actually demand, with volume cut and short intensity held.
What was actually measured.
Grouped by what kind of evidence each number is. A race result, a recorded power file, a model estimate and a rider’s own impression do not carry the same weight.
Race or event result
- Giro di San Diego
- Finished in 5:25, 24 minutes faster than the previous year. Gap to the age-group winner halved. Personal bests on the major climbs, including 4.5 minutes faster up Palomar Mountain.
Recorded or tested power
- Durability under fatigue
- 5-minute power after about 1,500 kJ rose from 231 W in 2023 to 274 W in 2025, roughly 20% higher at the same fatigue level.
- Late-race decay, same event two years apart
- At 2,750 kJ, power decay fell from nearly 30% to 15%. Cadence drop went from 6 rpm to 3 rpm and heart-rate drift from 11% to 4%.
Modelled power
- Critical power
- 261 W to 298 W across the build, with the new value validated at the event.
Subjective feedback
- How the day actually went
- He paced too high early, crashed on a gardening pot, cut his thumb so he could not open his gels, climbed Palomar without carbs, cramped, and nearly stopped at mile 47. The personal best was set on a bad day, not a good one.
The useful takeaway.
- Supports SEMIPRO for gran fondo riders with concrete event goals.
- Gives readers a direct source for performance improvement in a real event context.
- Connects the durability claim to a long-event outcome.
- Supports the specific claim that durability shows up as a smaller decay in power, torque, cadence and heart-rate drift late in a long event.
What this example does not prove.
- The 24 minutes compares two runnings of the same event a year apart. Weather, road conditions, group dynamics and race-day circumstances all differ.
- The durability comparison is between rides in different years under different conditions, not a controlled repeat test.
- Jasper had a coaching history before this build, so the result is not the effect of one 13-week block in isolation.
- Critical power is a model estimate, not a laboratory measurement.
- Individual result, no control group.
- No verified start-to-finish timeframe is published for this record yet.
Where this comes from.
Source video with full transcript, including athlete interview
How This Cyclist Cut 24 Minutes Off His Favourite Gran Fondo
Full transcript
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