I had to work this morning so I couldn't do a club ride.

I did have a time window to ride this afternoon, so I did go for a ride.

Conditions were sunny, temp about 90, medium humidity. Not awful but pretty warm.

I went by my general guide to drink 1 bottle/hour...First hour felt reasonably good, I was actually drinking a bit more than that 1 bottle/hr...when I came to a nasty hill (approx 12% grade, but only 1 km long)...I made it to the top and drank more water but I started to feel "off" and really nauseated. I was wondering if maybe I was drinking TOO much water and bloating myself...I limped home and had to "steal" some extra water from a municipal building's spigot on the way home. When I got home it was clear that I was borderline dehydrated and had not had enough fluids in me.

It was "only" a 2 hour ride but I went through 3 bottles and still got overheated and borderline dehydrated.

Other than drink more and avoid riding in the heat, any ideas on how to avoid this from happening?

In extreme heat, you need electrolytes in addition to drinking more. Plain water doesn't stay with you and can't do its job. Prehydrate with an electrolyte enhanced drink, make one of your bottles an energy drink (even Gatorade has electrolytes). If you need more, take some type of salt tablets (like Enduralytes).

Many people don't know this, but you can actually overhydrate and get water poisoning if you aren't getting salts, potassium, calories, etc. Not a dangerous factor in a 2 or 3 hour ride, but people have died from it during multi-day endurance events.

UK that may be it.

I generally save the electrolyte mix for rides more than 3 hours...and that has worked out well in the past but this was my first 2 hour "hot" ride.

Happens to me most every ride in the summer... argh

What did you drink in the hours BEFORE you went out riding?

I had a glass of water 15 minutes before. I had a cup of coffee 2 hours before. I had lunch 3 hours before, with lots of water.

you really have to anticipate, and hydrate well ahead, with electrolytes.

Can't wait till you feel thirsty or any symptoms.

At least do 1/2 water, 1/2 gatorade

ETA - coffee is a natural diuretic and probably made the situation worse

Yeah, I think the lesson I learned is to include the electrolytes even with shorter rides if it's really hot out.

Live and learn...

For a two hour ride -

I would leave with 2 32 oz bottles.

#2 full of straight gatorade - #1 that I can reach full of 1/2 gatorade and water.

When I drink the first bottle - pour half of #2 bottle into #1 bottle and refill both bottles with water.

Works for me - and it's been 95/97 down here the past few weeks

You might want to try Endurolytes from Hammer Nutrition. If I'm about to do a "hot" (95 - 100+ F) ride, I'll take one perhaps 15 minutes before I start the ride. Also, with the heat we've been experiencing lately, I've switched from two bottles of Gatorade on the bike to one water and one gatorade. For longer rides in the heat, I down an Endurolyte about every 15 miles or so.

My body retains heat very well. Good for winter, bad for summer. I've had heat problems in the past, even spent the night in the hospital once. Since then I've learned what weather is dangerous for me, what clothes to wear, how to "read" my body, how to pace myself, what foods to eat, etc. I'm having very little trouble in this weather this summer. Your feelings of very nauseated and being bloated are to me classic symptoms of heat exhaustion. In my experience, this feeling comes on in a very short time with no warning - fine now, 15 minutes later laying on the side of the road knowing I need to drink more and simultaneously knowing I can't because it won't stay in me.
What do I do? Learn what type of weather can get me in trouble (You got started on knowing that today.). I wear wicking jerseys, not cotton or wool. I start slower (for maybe a half hour) to figure out how the temperature, humidity, intensity of sunlight and my body are all interacting. After that I can push it harder but I pay attention to my "core temperature". I never push as hard as I can, or as hard as I would in cooler weather. I make sure the breeze or a shady route keeps me cool enough to dissapate my body heat. I tend to stay on flatter routes. Bigger hills will push my body temp. up quickly. If I do ride them I make sure to spend enough time cooling (my body temp.) down before pushing hard (speed or hills) again. Something I'm doing this year is drinking lots of water - probably twice as much (or more) than what you said above. All the above comments on electrolytes, Gatorade, etc. are good information and advice.
If you (or at least when I) got into the nauseated condition you describe, I've learned how to recover (it's a long process). First I just layed in the shade. When able, I started sipping water - very small amounts at first. You want it to stay in you. Eventually (after an hour?) I was able to take in fluid more regularly. I also knew I needed to eat, but what would stay in me? I've discoved grapes work for me - liquid, sugar, and small. I could eat a grape, then a few minutes later eat another, then another. Over an hour it'll start adding up. After an hour of two of resting, sipping water, eating grapes, I was to the point I could eat more (carefully), drink more and start riding slowly, assuming no one had come to get me by that point.
Know what weather has caused problems in the past. Pace yourself, dress right, get acclimated to the weather/heat at the beginning of the ride before pushing harder. Make sure whatever is cooling you is balancing out the heat you produce. Drink lots, and if you're out more than an hour or two, consider electrolyte replacements as posted above. Prevent heat problems or exhaustion, because it comes on so suddenly without any warning. Learn you body's warning signs, and also learn what to do to start recovering if you end up with heat problems.
Hope this helps. Sorry it's so long.

I started to feel "off" and really nauseated. I was wondering if maybe I was drinking TOO much water and bloating myself...I limped home and had to "steal" some extra water from a municipal building's spigot on the way home. When I got home it was clear that I was borderline dehydrated and had not had enough fluids in me.

It was "only" a 2 hour ride but I went through 3 bottles and still got overheated and borderline dehydrated.

I just re-read this part of your post. For me, a classic symptom of heat exhaustion is feeling like you've had way too much water and feeling bloated, and also the nausea. This is one of the ways one gets into trouble. You feel like you've had too much to drink, so you stop drinking, which then makes you even worse. I suspect you're way more than borderline dehydrated. My prediction is that you'll be wanting to drink water all day tomorrow.

Regardless what you drink, at that temperature and humidity, a bottle every 10 miles might be better.

He is so bang on it, it is shocking for a BF thread! I use the same guideline as you do but chop it in half when it is hot out. Don't underestimate that sun; it plays a role too!

My favourite supplementation for water is L-Glutamine. I use that when I know I'll be squeezing up hill climbs whether it is hot out or not. It keeps me fresher for longer and when I'm not reading 'cures' my IBS .

This is worth repeating again especially since it seems so few recreational athletes understand it. You can't beat physics; most of the work your muscles are trying to do is just "lost" as heat, so the harder you're pushing, the hotter you get. In hot and humid weather, the amount of heat you can dissipate is limited, so efforts you can undertake in mild weather can easily push you over the edge in hot weather, regardless of how much water or electrolytes you intake... So hydration is important but can never be a cure-all in the heat. Stay safe and have fun!

You need to drink plenty before you ride not just riding days but everyday and not just during exercise. I ride in heat index of 120, and I'm fine. I drink 2L everyday though. If I haven't ridden for a long time say 1 month, then go out at a high intensity I will feel like crap. I puked while I was cycling - while moving. I immediately felt better after I vomited. That day I was probably dehydrated, drank too much during exercise, and I ate too much and too fast for breakfast right before cycling.

Thanks for the tips guys.

I won't let this "mistake" happen again.

Luckily, my morning commute today had temps of 70 so I was fine with just some water.

Don't under estimate the power that squirting some water on your head has. It is amazing how much this helps cool you down.

I rode an organized century in northern Illinois yesterday. By the finish the temperature had reached 100 degrees with very high humidity. In the course of the ride I estimate that I drank 14+ bottles of water / water with NUNN / Gatorade, but I simply could not absorb enough water and was somewhat dehydrated at the end. While just short having the of chills, I did mild nausea, bloated feeling, and had stopped sweating about the time I rolled in. If the route had been ten miles longer, I would have had to stop to cool off. As it was, I felt kind of hung over for the rest of the day and this morning. A hundred mile ride is usually no big thing, but this one took it out of me.

Milkbaby is right; even with electrolytes, your body can absorb only so much water, and shed only so much heat. At some point, you simply must throttle back.

Datlas, out here, I am drinking a minimum of 2 bottles/hr and still lose weight. Assuming I leave the house at 6:30am. Once the temps get over 100, I cannot keep up and have to limit my rides to 90min or I stop sweating.

Are any of you guys in the heat other than when you're on the bike? If not that could be part of your problem. Its been over 100 degrees 37 days so far this summer here and we're all still riding. Our tuesday evening group ride happens at 6:00 and its still well over 100 then. The other thing that you should pay attention to is your diet. Eating a crappy diet is an easy way to feel like trash in the heat.

I like carrying an uninsulated bottle in my middle back pocket frozen solid. Great cooling effect and you can pour the water over you as it melts.

Wow. You thinking of coming back east? I bet you could ride more! Of course the housing costs here suck so you might have to sell your bikes to pay the rent...