6 Factors that Influence Sweat Loss:

There are a huge number of factors that can influence our sweat rate, which means that the amount of sweat we lose in an individual session can be highly variable.  This makes it difficult for us to provide generic advice on how much to drink during a session.
A great place to start is on the bike approx 500ml per hour in low to moderate temperatures, (more to thirst and with increased temperatures).

2L minimum off the bike again more to thirst and in increase temperatures.

Here are 6 factors that influence sweat loss:

1. Exercise Intensity:

The harder you work, the more power you produce, the more heat you generate, and the more you sweat.

2. Temperature:

The hotter you are, the more you sweat to help lose that heat.

3. Humidity:

The higher the humidity, the more you sweat, as sweat efficiency at evaporating and losing heat declines.

4. Clothing:

The more clothes you're wearing, the hotter you get, the more you sweat.

5. Heat acclimation:

This can increase plasma volume and increase sweat rate, making us better at dealing with heat.

6. Genetics:

Some of us sweat more than others due to our genetics.