I'm looking into a Wilier Izoard XP from CC and noticed that it comes with an English bottom bracket. Is this a big disadvantaged compared to bikes with BB30 or Cervelo's BBright?

No. You're not going to be dropped in your local hammerfest by the fact that you have a different BB diameter. English is the standard still.

Are you racing? The traditional english BB isn't the stiffest, so you do lose (just a tiny bit) of stiffness/power transfer compared to BB30/BBright, but most modern BB's use external bearings and wider spindles in the older shell, so it's not that much of a difference. If you race, especially if you like to sprint, you might notice and appreciate BB30/BBright. But most riders probably couldn't tell the difference.

Nope, not a racer, so you're right - I definitely wouldn't notice a performance difference. Do different bottom brackets limit the types of cranks you can put on a bike?

Regardless, it's good to know that English is still the standard, and so must be compatible with most out there.

Generally, no.

There are a few BB/crank systems that are proprietary to the frame but those are the exception.

All component manufacturers still offer their full product range with BB/Crank that are compatible with an English thread BB (Also known as BSC).

if you actually looked at a gxp bottom bracket (or any other bottom bracket) and then compared it to BB30 you'd wonder why it isn't obsolete yet.

i really dont know about the future of BBright (what a pretentious name) though, just seems like a small variation of BB30 from a company wanting to license their own proprietary technology. hopefully "open source" BB30 pans out

BB30 and BBright are a little better from a design standpoint, in that the bike can have enough strength and decent sized bearings without resorting to hacks like outboard bearings, while being a little lighter. But I challenge anyone to even define bike "power transfer" in engineering terms, let alone measure a difference between BSA and BB30. There isn't a difference in anything measureable, like speed up a climb at a given power output. There will be more of a difference in crank stiffness between crank designs on the same BB vs different BB standards. (see https://fairwheelbikes.com/cycling-bl...nk-test-4.html)

BBright leaves a little less heel clearance than BB30 although it's still more than outboard bearing BSA cranks. The worst thing about BBright is that it's new and not widely adopted, so you have a small selection of cranks that will fit the frame.

Installing BB30/BBright bearings requires special tools that are more expensive than the ones for BSA BBs. And some BB30 bearings creak inside the frame and require special locking compound. I wish my BSA frame was BB30 because I am jealous of the heel clearance and there's a really good BB30 only crank that I would like to use. But it's not worth getting a new bike to get it.

As far as crank stiffness goes- I recently switched from Lightning cranks to Sram Red, which are significantly stiffer according to the Fairwheel tests. I can feel a difference. And before the Lightings I used some FSA ISIS cranks that were super flexible. The Lightings felt like they were hewn from granite in comparison. But I could not measure a difference in my performance between the cranks. In fact my best historical power numbers were set with the noodly FSA cranks.

I love everything about the Izoard but am still slightly hesitant about it not having a BB30. Most of the other performance bikes I've looked at have switched over to that, and I can't help but feel like I'd be missing out on more modern tech by going with the standard English.

I guess marketing is working on me after all.

BB30 really doesn't make that much of a difference. In fact is more of a pain in the butt to install and do work on and it tends to creak.

I bet my R3 with its GXP BB is still more stiff the 90% of the BB30 bikes out there.

I'd pick up the Izorard before they run out. Those M10 wheelsets are in limited supply