What strategies can be employed to optimize hydration during long cycling events with limited water stops, considering factors such as individual sweat rates, ambient temperature, and humidity? How can riders effectively gauge their hydration needs and adjust their intake accordingly, taking into account the variability in water stop frequency and accessibility? Are there any specific hydration products or systems, such as hydration packs or bottles with built-in filters, that have been shown to be particularly effective in these situations? Additionally, what role does electrolyte replenishment play in maintaining optimal hydration, and are there any recommendations for electrolyte-rich foods or supplements that can be easily consumed on the bike?