A well-worded answer! You touched on the issue that makes threads like this of dubious value. The "comfort line" as you so nicely put it is as personal as saddle choice. For me, 7.5 miles would be right on the edge. At 10 miles in my ordinary clothes and under garments, I would arrive feeling chafed and abused. At 5 miles, it would be no problem. At 7.5 miles I might be starting to get a little uncomfortable, but I could do it. But that's just me.

Some people can ride all day in jeans and cotton undies. Some of us prefer things to be more securely packed. It's worth talking about, but there's no substitute for "try it and see."

I have a just under 8 mile ride. I suit up if it's really cold or really hot. I hate being totally drenched in sweat, and where I live it can get pretty hot. But one nice days I wear what I work in. Not haveing to peel off bibs does make the transition easier.

hahaha!

I'm with you on baggy jeans, or any jeans, for riding a bike. But I'll ride as long as you want in a tech tee, boxer briefs, baggy athletic shorts, and my leather saddle. No need for spandex.

My commute is 7.5 miles each way, but hilly as f$%&. I don't wear my typical road biker clothes, but I do wear clothes that wick sweat. I also wear a backpack that consists of my laptop, a change of clothes, and snacks. I freshen up when I get to work. Of course you will have to discover what works for you; this is what works for me, so I encourage you to try it

Actually, I've settled on normal clothes, though making a few modifications.

I got a few pairs of stretchy old navy khakis with 2% spandex to wear while on the bike. Surprisingly very comfy, especially in cool weather, and they look like normal cotton pants. Those pants with a cycling jacket over a normal shirt, or thermal base layer under a normal shirt has been perfect since I started the new job in september. So, from ~75F to 15F I've been nice and comfy. I will say at the upper end of that range the decision was much more on the fence...I got a bit 'moist' with the khakis.

I work slightly weird hours, starting at 11am a few days a week. So, in the dead of summer, I may have to adjust things, either bringing in a change of clothes, or just riding very slow.

On the other hand...we are very casual here. Linen pants and a wicking polo shirt would be more than cool enough unless it's abominable out...like over 100 and humid.