UCanttouchthis is completely correct. I've been riding bikes with carbon forks for years now at well over your weight and a carbon bike for the last year, they're no no less likely to fail you then anything else. Although you can't get to what you have exactly the new subcompact cranks will give you a 32t chainring while the right rear der will give you a 34t cog, assuming you're still running a 28 on the rear which is where old ders tended to top out at you'd be pretty close gear wise. Honestly, I've ridden that bike before and you've been missing out on some fun stuff. Don't be afraid of the extra gears, they work nice too.