I don't know. I'm deeply sceptical of Social Return on Investment because while it's relatively easy to come up with the costs side, it relies on too many cooked up numbers on the intangible social benefits side. I just looked at where all the benefits come from in the Edinburgh Leisure report and it's from a valuation of the health benefits from their activities. They might accurate but I doubt it and when the consultants are distancing themselves from the data behind their own report, you have to wonder.
If you're looking for cost / benefit analysis of cycling infrastructure there will probably be better estimates of the benefits in other places. I'll have a root around.