Picking up from the http://www.bikeforums.net/commuting/...e-curious.html thread...

I was at a conference with a bunch of doctors last week so was able to talk to a few about this.

About 1-3% of the population experiences hyper-sweating. EG, they sweat more than normal, it is somewhat uncontrollable, and the cause is not well understood. (The OP and [MENTION=21724]cyccommute[/MENTION] perhaps in this group?) They believe that for the vast majority of these it is food related such as too much sodium, fat, processed foods, etc. With these, once understood, it should be controllable through diet. For a few of these, roughly 1/10 of 1% of the population, it is likely genetic and uncontrollable without meds or other intervention. For another similar size 1 in 1,000 group it is thought to be mostly stress/psychological.

For the rest of the population, sweat is normal and largely controllable. The top causes of consistent sweating are being overweight, poor physical fitness, and poor diet. They all noted that sweating is a much greater problem in the US than Europe and Asia due to our food supply (high sodium & preservatives), lower daily activity, and being overweight.

Beyond fitness, diet, and weight they said that moderating activity to stay at or below the heavy sweat threshold, dressing appropriately, and staying hydrated were the keys. They distinguished between light sweat and heavy sweat and noted that even heavy sweat did not necessarily produce any odor in many circumstances. Odor comes from bacteria, not sweat. It is when sweat is trapped and cannot evaporate as it develops that the bacteria and odor develop. Bicycling examples are sweat trapped in helmet hair or folds of belly skin.

Specific to bicycle riding... They confirmed that helmets and gloves will cause considerable sweating, bacteria, and odor. One also mentioned tight fitting shoes. I'll leave their thoughts on helmets to another discussion but they were evenly split 3:3. Any leaning forward will increase sweat, particularly for people who are even slightly overweight. Efficient geometry that allows progress with as little effort as possible was mentioned as were e-bikes.

In theory at least, someone should in most cases be able to ride any distance on a bicycle with less sweat than walking that same distance in the same conditions. The thought being that someone on a bicycle will experience greater cooling per kilojoule of effort. They noted that ambient temp has almost nothing to do with sweating but the dew point does. Their example was playing golf in 95f Arizona can be sweatless while in 80f Hilton Head can be a sweatfest.