I want a racing bike for commuting and general use, that can also be used for touring occasionally - i.e. can support a rack with a bit of luggage on the back. I've used a racing bike before, but of course with about 30kg on the back the back wheel eventually bent and then broke completely under the weight. What would be perfect would be to put a wider tyre on the back wheel to support the rack, but as far as I can see ALL racers are made with the gap between the chainstays (the part of the frame between the pedals and back wheel) too thin for anything but racing wheels (unlike e.g. triathlon bikes which usually leave enough space for mountain bike wheels, so you can put pretty much any type of tyres on them).

So does anyone pls know of a racer made that can take wider wheels if needs be?