Probably the most reliable method would be to try to take the measurements from good quality photographs in a magazine such as Cycle Sport. They have several large format pictures which might allow such measurements. It would be hit or miss as to which riders you got though. I'm not sure I would trust any published data from the teams or manufacturers. I don't mean to impugn anyone, I'm not saying no manufacturers can be trusted only that while some manufacturers are trustworthy, others might not be.