Biking and Hydrating Question

Hello!  I haven't been on here for a while, we've been so busy with the boys!  They're doing awesome; Geordi's 2nd birthday is coming up in a month, I can't believe how quickly they've grown up! 

We've been biking with them a lot recently and I'm wondering how much water we're supposed to provide them during our rides.  Say we're out for 30 minutes to an hour, how often should we stop to give them a drink?  It's getting pretty warm here, 60's-70's, and I'm worried they'll overheat.  Would it be ok to have them carry a bag while we bike or would they get too hot with it on?  It would be nice if they could carry their own water if we need a lot, but the bag we have seems bulky and would annoy me if I had to wear it while running lol!  They need a camelbak for dogs!  Weeknights we only run them about 3 miles and stop once to catch our breaths, but no water, is that ok? 

Here's a pic of my husband and his father with the boys on the bikes:

They now have 4 shoes each, which is so much better for their pads!  I was joking with my husband and said they need doggles now haha! 

Mom to Geordi, born 4/30/08 and Miles born 7/29/08

Hydration is as important to dogs as it is to us.  If you were working out at a gym you would be told to bring a bottle of water with you.  I'd say every 20 minutes at least.  I wouldn't let them drink too much at a time or they may toss it back up which would defeat the whole purpose.  

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maybe this will help.  doggie backpack for carrying water:

http://www.everythingwolf.com/forum/threadview.aspx?thread=4487p1