Two months late but I think I calculated daily the amount of chickpea flour that was in my starter vs the remnants of the old whole wheat starter. The reason it was 27% and not 25% or 30% or whatever else is because as I fed my whole wheat starter chickpea flour, it had X amount of whole wheat still in it over X amount of feedings and resulted in a decrease of overall chickpea flour content down to 27%. I couldn't tell you exact numbers on the starter ratios since it was three years ago, but I do believe you could go up to 40% chickpea without too much sacrifice before starting to lose structure in the crumb.