Yes they do, they're fine for a short ride,I've found that two hours seems to be the limit before the water or Gatorade seems warm.By the time you or the drink is hot enough,any liquid will suffice.I feel the temp. will be maintained longer than a sufficient quatity.In hot weather,the MINIMUM water intake is 8ozs. per 30 minutes.A big bottle could last a couple of hours,nothing to sneeze at as far as cycling time in heat.