I've had one heck of a time with this myself. One thing I do when installing is put a little bit of water in the bladder to help as a guide for the rest. I've also noticed there is some sort of wire or firmer part of the bottom of the bladder, when shoving it through the opening that is in my opinion far too small I always try to hold it by this portion to make sure that nothing is getting stuck higher than it should. But my best guess is it isn't as hard as it seems and you're installing the bladder properly.

When refilling with the quick refill part I've noticed a couple things that lead to the water shooting back out and have had this problem myself quite a bit. 2 things I've noticed help, first is to make sure the water bottle is actually pushing down the opening in the spout of the bladder. It seems like some sort of actual opening that has to be opened and by making sure the outer edge is pushed down properly all the way will open it allowing water to flow in. Second thing, and this has been a huge help, is when I'm refilling I make sure to bit the straw tube to open up an exit for air that is in the bladder. I believe there's some sort of suction/vacuum action happening and even if doing the first and ensuring that water can get into the bladder this vacuum seal is preventing water from going into the bladder. It definitely tasks some messing with it and isn't very intuitive but that's what I've found works for me. Also I've not been able to empty one water bottle into the bladder in one squeeze. It usually takes me 2-3, and in between squeezes I make sure to stay biting on the straw to leave space for air to escape from the bladder as I think water goes in faster than air can escape the bladder.

I hear you.

First, you need to have proper water bottles. E.g. the Elite Fly water bottles don't work - they'll first close themselves before squirting into the hydrapak.

Second, I'm myself struggling. The bladder itself has a capacity of almost 1l. Canyon says it's 0.7l (size M). No matter how carefully/diligently I place the hydrapak in the frame, I can only fit 0.5l into it. I tried with pre-filling the hydrapak as well, but it didn't help.

Thanks!!

After further searching, I found an old facebook post with 2 ways

1. Place ~ 200 cc water in bladder
2. slightly fold the bladder but not completely so that it can unfold..
3. Insert bladder
4. clip in. the top piece
5. Push in the valve (top tube not bite valve)
6. blow air which inflates
7. Fill

Option 2 (I think you can combine this with one)
Steps 1-4 same
5. Shake the bike so that the water helps unseat the bladder and opens it up
6. continue to fill bladder

I was able to get most of my 24 oz bottle in. good luck

how do you refill while riding in say IM race. I have Scott Plasma 6 and it is easy to fill in container/bladder while riding using any bottle type..no spilling

This is my issue too, and why I bothered logging in. I cannot for the life of me figure this out, to the point where I'm starting to look at other bottle options. The super sleek integration of entire frame was a big reason for choosing this bike, though, so I'm pretty disappointed in how finicky it is. A lot of other companies appear to have a pretty easy filling method, but this is more often than not just a huge hassle. Anyone else figured it out?

What's your issue? Putting the bladder in-fold it around the tube a little to help it slip in. As for filling on the bike never had a problem, sure some water might splash around but its only water, who cares when your bike is otherwise covered in sweat during a race?

It's not the splash- you're right, who cares- but it seems like I can only get part of a bottle in and then it just overflows. I'm not sure if biting the valve is the trick, partially filling it first, or what, but I've really struggled with filling it despite a seemingly well-seated bottle. Certainly don't think I can do it quickly right now. I'd expect to get more on the bike while riding than in it with my current luck.

I'm definitely open to it being user error, but I haven't found a good trick myself which is why I'm here.

What size bike?

I find refilling can have some spilling if the valve is not pushed all the way down. Once I figured this out and have been taking a moment to be sure it’s down, it’s been pretty good.

It’s not great but I can get about 3/4 of a bottle in. For me blowing some air to inflate the bladder prior to adding the water helps tremendously. Also you might try to bite the valve when the flow gets sluggish so that there is a pressure difference which allows the fluid to flow better.

The hardest part for me is to get a cap that will stay open when I push it into the slot. Often times the cheaper bottles cap will just close down. What type of bottles do the others use. I’ve been using the IM bottles.

Mine is a size small. It looks like the bladder is nearly coming down to the integrated storage. I wonder if frame size plays a part in this problem- perhaps it's contacting some of the carbon that separates the 2 compartments?

Ahhh that might explain the issue. I've read that this seems to be a problem on the smaller bikes, I have a large and no issues.

Also I think in the small the bladder is 500ml not 750, so maybe check they haven't accidentally given you the wrong size?