.............Repeat the experiment at different temperatures. If you can't do this, then use Lon Haldeman's 75% for 10 degrees F rule as a guide: Haldeman needs 60 oz/hour at 100F, roughly 75% of that, or 45 oz/hour at 90F, and 32 oz/hour at 80F. At 70F and below, he needs about 15 oz/hr.
The bloating paradox section is worth its weight in gold. Too much fluids and not enough sodium......worth reading the first link for anyone who gets nausea, confusion, puffiness, and/or headaches on long rides.
Ultracycling: Low blood sodium (hyponatremia)
SSE #88: Hyponatremia in Athletes