We have a beginning of shift meeting with safety being the first thing. Today, I was told it is too hot to ride a bike to work. I told them you only feel it when you stop. 10.5 miles each way. On a normal day I will not even bring water. The last couple of weeks I drink two 20 oz each way. But I never feel the heat until I stop, then it takes about an hour to quit sweating. The high is supposed to be 103 today no telling what the heat index will get to. August is usually worse. 106 was the max without heat index that I have rode in. Where do you call it quits? I only feel it when I stop and I make sure to stay hydrated.

Keeping well hydrated is important when riding in the heat since often you will sweat a lot, and even more so when you factor in the high humidity that goes along with summers in the south. It's been pretty hot and humid in the Northeast as well which is why I prefer to ride very early in the morning; commuting to work isn't much of an option because once it gets over 90 and it's humid I need a shower which I don't have at work.

for me its not a matter of how hot it is, its more of how humid it is. I have ridden in 100+ (dry) heat and feel great, the other day I rode almost 10 miles in temps that were in the upper 90's but the humidity was high and it kick my butt. Like you said, it fine until you stop

Just add water... Internally and Externally.

I've arrived at my Mom's house after riding for 7 miles perfectly comfortable in 102F temps. Of course, before leaving work, I completely soaked my cotton shorts and shirt. I kept adding water whenever I felt that I was beginning to warm up. The evaporation worked as a swamp cooler, and I was fine.

Then again, we don't get muggy days all that often here in Portland.

I'm not quite sure. I'll let you know next week, as they are calling for 100+ temps with high humidity here in Memphis. I can't wait

When sweat continually stings your eyes.

Last night on the way home this was a problem. The first mile or so is uphill, so I am slow with little wind. Once you get the downhill I take the shades off and let everything dry out for a bit.

I suppose the answer is going to depend not only on the humidity but on distance, terrain, vegetation/surroundings and on the body in question (both physique and acclimatization). For me, somewhere between 115 and 118F and moderate humidity begins to be uncomfortable but I have seen people who really suffer at 90F. I think it is much more difficult for people who have always lived in places where the temperature stays below 80F for most of the year because they never really acclimatize.

It sure helps if the roadways aren't crowded with concrete buildings and parking lots but have green buffers. Unfortunately, that is contrary to the new densification Kool-Aid. I fear we are turning our urban heat islands into urban ovens. Or, considering the toxic reactants the cars add, urban ozone cookers.

I don't know how hot is too hot. My co-workers think that I'm insane for riding a bike, regardless of temps/weather.

LOL, that happens after about 10 minutes for me. I'm looking at getting a Halo headband for that exact reason.

So naturally, any of your co-workers who drive cars without working A/C were also told due to the unsafe condition it was too hot to drive to work.

Usually if they can't come up with a good safety message its pick on the guy who rides a bike to work. I have 3 blinky lights on back and a reflective shirt. I still hear I almost ran over a guy on a bike this morning. They can't and are not telling me that I can't ride to work they just like to give me crap about it. Most are a bunch of ex Navy guys. So, they respect me for riding but like to be mouthy. I don't get any more or less than anyone else.

Ex Navy types and safety meetings? I'm thinking that you work at that power generation plant on the lake. Passed through your town several times while traveling I-40 over the years. Even thought about doing a move there at one point...

Tell those co-workers of yours that they could get you a custom jersey to help with your being visible- the word "ESBAM" on the back and "BOHICA" on the front. PM me if you can't figure out what they stand for.