The science behind your plan

One glucose carb caps at ~60 g/h — the gut's SGLT1 transporter saturates. Eating more of a single source won't raise it.

Add fructose (own GLUT5 transporter, ~2:1 glucose:fructose) and the ceiling lifts to ~75–105 g/h.

Scale to duration: ~1 h a rinse is enough · up to 2 h ~60 g/h · 2.5 h+ ~90 g/h (2:1).

Gut-trained athletes can push 120 g/h in long events — it out-oxidized 90 g/h in trained cyclists.

"Train the gut": a sustained high-carb diet roughly doubles SGLT1 capacity over ~2 weeks.

Drink mix is best kept at ~6–8% carbs (60 g per 750 ml); well above that it slows gastric emptying. 2:1 mixes tolerate up to ~10% — the plan never mixes past that.

Sweat rate is typically 0.5–2.0 L/h (endurance avg ~1.28). Variation is huge — measure yours by body-mass change over a timed ride.

Over-drinking is the real danger: too much hypotonic fluid causes hyponatremia (blood Na < 135 mmol/L). Aim near sweat loss, not weight gain.

Runners, take this doubly seriously: 13% of Boston Marathon finishers measured hyponatremic — driven by drinking too much, not too little.

Sweat sodium averages ~0.8 g/L (range ~0.25–2) — roughly 1 g/h for endurance athletes. Replace more on long, hot days.

Heat acclimatization conserves salt, lowering sweat sodium — so your need tracks heat-adaptation, not just temperature.

An ergogenic dose is 3–6 mg/kg body mass (70 kg ≈ 210–420 mg), ~60 min pre-start — worth ~2–4% in endurance.

Benefit plateaus above ~6 mg/kg; ~9 mg/kg only adds side-effects. So 6 mg/kg is a sensible ceiling.

A late top-up works too: 100–200 mg (flat cola, a caffeine gel) in the final hour. Sensitivity varies a lot.

A power-balance model turns the route into time: your power fights air drag (½·ρ·CdA·v³), rolling resistance and gravity on each grade — so climbs stretch the clock, descents compress it.

Defaults are typical road values (CdA ≈ 0.32, Crr ≈ 0.005, air 1.225 kg/m³, drivetrain ≈ 97%), fully editable. A safe descent-speed cap keeps downhills realistic.