I use the camelbak hydrapak. It’s a minimalist pack that holds 1.5L. Sits high enough on your back where you can still access jersey pockets. And is low profile enough where you can put a rain jacket over it.
It’s strap system does not look as secure as the USWE, but I have had no problems with it moving about.
I considered the USWE also, but a few things steered me to the camelbak - would be interested to hear feedback from people who have the USWE.
- the reviews of the USWE bladder say it’s hard to open, close and fill. This would be a problem for races where I want to refill quickly.
- the strap and buckle on the front look almost too constricting for hot rides, and make it harder to unzip your jersey. I do a lot of climbing, so want to be easily able to adjust my jersey.
- looks like the buckle might sit on top of an HRM, which would be uncomfortable, and affect the functioning of the HRM.
The camelbak works fine on these fronts.