Originally Posted by
FlMTNdude
Great for running mountain trails in an arid climate. Otherwise they restrict air flow and evaporative cooling as mentioned. If you are one of those who don’t sweat it may work. Otherwise I have two bottle cages on the bike and not difficult to reach down and have a drink.
I have a small frame on my MTB and the standard position of the cage mounts means that only a small bottle will fit (550ml or less). This isn't enough water on hot days or for rides over an hour. I may also look at more creative ways of carrying enough water as I do have several water bottles at home.
I've ridden with a small backpack a few times (a Deuter one) and it wasn't too bad, but then it didn't have any water in it.