That depends: you write you want a race-fit bib for very long rides. Usually for such long rides, I would prioritize comfort over aggressive fit (although they need not be mutually exclusive).
For indoor rides, I would stick with either old bib shorts or something inexpensive. My old pair of DHB classic shorts works very well here. And since trainer sessions are shorter (1.5 hours tops), long-time comfort is less of an issue.
@batwood14
Yup, 7Mesh cycling clothes are excellent, if not cheap.
I’m really shocked that these aren’t the #1 bib choice over Rapha.
I got a pair of S-Phyre bibs for around 50euros. Fantastic bibs, definitely not worth the full list but the quality is right there with the high end stuff from Pearl, Craft, Sportful, etc.
They often have them on sale on the Pearl Izumi Factory Store.
This may seem out of left field, but I’ve become extremely enamored of Planet X’s Pro-Line 365 bibs. They are fairly compressive and somewhat thick, so they aren’t the coolest in hot weather, but if you’re looking for a more constructed short these are just the ticket.
The pad is really good, too. I find it as comfortable as any for me on 6+ hour rides. I generally choose them over my high-dollar bibs unless it’s really hot out (or I need to wear my team kit).
For the best news of all, they are frequently on sale for £20/pair.
I +1 this but would add that they come quite high up your belly. As you say OK for cooler weather. They are wearing well too.
How can some bibs cost as much as a Varia Radar? I find it hard to justify dropping $200 for some Assos bibs 
Are there any brands in this thread that haven’t been mentioned? 
If so I’m buying some so I can add them here too.
Voler. Their Black Label bibs are very good.
Yes. Pedal Mafia
https://www.pedalmafia.cc/collections/mens-pro-bibs/products/mens-pro-ltd-black-stealth-bib
I picked these up on sale for $130AUD and they are very nice. Great straps, compression and chamois for the price. I had been using Castelli before but got sick of the logo peeling off.
Assos my friend. I was experiencing the same situation, and after ending four days of consecutive century rides with an extremely sore ass, I said “NO MORE”. One of the more experienced riders recommended Assos with a different kind of chamois cream and I haven’t looked back. Have finished a number of centuries since with no discomfort. The only drawback…price! I paid close to $300 for my bibs, but I came to the conclusion that my comfort for 4+ hours, while doing what I love, is worth the investment. Good luck.
GCN branded Assos Mille S7 are £100 normal price.
You can get much better prices at the Swiss Iconic outlet. If they don’t have your size, check back often. There’s always new stuff coming in stock. Mens - Bibs & Shorts – Swiss Iconic
Worth noting: After years of Assos use, I recently switched from Assos to Rapha. They just fit my particular build better. I preferred the older Assos models and every year the new models seemed to get worse for me. The Rapha fit me more like my beloved ancient Assos.
Best goofy designs: Cheap Kidito KT bibs and sleeveless jerseys from Aliexpress. Ridiculously cheap, plush feeling lycra, with an array of designs. Problem is that the pad and stitching isn’t great and aren’t really suited for rides over 2+ hours. Still, I’m all about my Dio de los Muertos kit!
Best looking: Pactimo custom made club kit. Expensive, but just fantastic colors and excellent construction. Problem is that they don’t fit me perfectly, so, once again, long rides are a no no. I’ve gone on half centuries where I’ve been chafed and bleeding at the end
Best for the money: dhb Aeron Speed. I keep coming back to these bibs, no matter how many other brands I try. They’re unsexy, the lycra is coarse, but they stay put and the pad and stitching is excellent. They don’t last more than a year of hard riding, but they’re cheap enough that you can replace them after a year and you don’t feel it that much.
Castelli Free Aero Race bibs
They come in navy blue which I love and are have a great crotch design that never gets in the way.
They are overall very tight and look aero, but the part above the knee seems to be made for sprinter sized quads, or maybe 185cm+ tall riders, so don’t get them if you have skinny climber legs.
Rapha Cargo bibs are great for trainer sessions, especially if you have your fan system setup just right.
I’m a 5:30am rider and i find the chamois is superb for the static nature of the training (it’s a slightly thicker pad) but i can tuck food into the pockets for when the longer sessions kick in, but i can also put my phone in the pocket and run wired headphones from it (until i can get some wireless ones!). The pockets keep things locked down, and i can reach into them during recovery sections of intervals etc, without having to lean about to try and reach things around me (which is when things go a bit wrong).
Does anyone have experience in the new Rapha Indoor, Castelli Insider or Velocio Ultralight shorts? I’ve always used my last season’s team kit on the trainer, but am curious if there is a legitimate benefit to the cooling benefits or chamois of their indoor bibs
At this point I’ve tried enough and I wouldn’t spend any money on anything not made by pactimo
I eventually need to branch out but Rapha are my go to. The core line is $115 and like them better than most of there most expensive bibs.
+1 - I have the Pro SL long and they are my favourite pair by a long shot. Mavic make a decent pair too.
Rapha pro team are really nice. I like the pro team aero version a bit less. They’re nice enough, just not as comfy for me, and massively wide straps!
I highly recommend Castelli Free Aero bibs. I have some old ones with the Progetto X2 pad, but crashed in them in August. Recently bought the new version (4.0) - only £67 on sale! I wore them first time yesterday for 1.5 hours on the trainer and found them pretty comfy. The pad is quite short at the front, which suits for a low position with no bunching. I was shifting around slightly near the end of my sessions - just breaking them in I reckon. Only real complaint is the straps are quite thin in terms of width, so tend to twist and bunch up slightly.