Hydration on the Bike vs. Running

The amounts you describe are very close to how much I drink on the bike during an IM.  If conditions are mild, I'll drink 1 to 1.5 large bike bottles per hour (24 to 36 oz/hr).  I guess that's toward the lower end of your 12-16 oz per 20 min.  If it's pretty warm, I'll up that to at least 2 bottles per hour (~48 oz/hr), which is about the high end of your range.  These things can vary quite a bit from person to person, but in my experience you should be drinking just as much on the bike as you have been drinking in your marathons.

I think the single biggest mistake that results in DNFs in an IM are nutritional mistakes, usually dehydration.  Most of those mistakes are made on the bike, and sometimes compounded by going too hard.  That's been my observation.  So, I'd recommend sticking with what's been working for you in your running and not cutting back on your fluids on the bike.

I try to follow this guideline...  If you find you need to pee more than once an hour, I'd take that as a sign you could cut back.  If you've gone more than two hours with no urge to pee, you should increase your intake.

-Steve

That's excellent advice and I will definately use it!

Thanks.

Thanks for the replies.  I'll make sure to give it a try a few times before I get to race day.  Good thoughts on the pee test.  Now the question is, if i have to go once an hour on the bike, do I pull over, or just let her fly from the bike. And if it is from the  bike, is this something I should practice as well

Thanks

chris

Hmmmm....that's sort of a personal question... kinda like should I ....

nevermind I'll keep it PG-13.

I've done it both ways. If you want to go on the fly, try to do it on a long downhill, stand, relax and let 'er rip. Best if you have an extra bottle of water on board to rinse off after. I've found it both liberating, and disgusting, at the same time :-) If you'd rather pull over, just try to find a discrete spot, behind a tree or something. Or, there are usually portapotties at each aid station. It's only a minute or so, which is no biggie in the grand scheme of an IM, unless you're gunning for a top AG spot.

My 'once an hour comment' might have been a bit extreme, but you get the idea. Aiming for the "at least every two hours" range is probably a pretty good gauge of proper hydration on the bike leg of an IM. Something to pay attention to in training to see what intake works for you.

Lots and lots of good advice over on Rich Strauss' website. I think it's some "must read" stuff for any aspiring Ironman

www.cruciblefitness.com

-Steve

This isn't directly related to hydration on bike vs. run but it is somewhat on topic.

Basically an article addressing a relatively newer shift of thinking about drinking TOO much water.  Probably became news after the most recent death with the College hazing.

Michael

http://www.msnbc.msn.com/id/6929115/

Hey, let's keep it clean....ok?

Yes, I guess we didn't really discuss what we were drinking, only how much.  For the quantities I was describing earlier in this thread, I take about 1/2 water and 1/2 sports drink.  My drink of choice on the bike is Cytomax.  Between sports drink, gels, bars, and salt tablets I try to make sure I'm taking in around 700-800 mg of sodium per hour.

-Steve