One of the main reasons I use my bike is because it is significantly faster than other methods of transport I have available (metro, bus, walking). Slowing down to avoid sweating negates that benefit. (Though in summer, I usually bring a spare t-shirt. Sweat itself doesn't smell, only after bacteria have had a time to act on it. Cycling to work after a shower then a change of t-shirt works fine for me - though I am not a heavy sweater).