A: ISO MIX helps a lot because it provides carbs + electrolytes while you sip — so your bottles aren’t just water. But for the Fred Whitton’s duration and climbing, ISO MIX alone usually isn’t enough unless you’re drinking a lot and your bottles are strong. Most riders perform best using:

• ISO MIX in bottles (steady carbs + hydration)
• Gels for quick top-ups (before/after big climbs)
• Bars for variety (especially early on)

Think of ISO MIX as your “baseline fuel”, and gels as your “on-demand boost”.