My first question for bike forums.
Can anyone point me in the direction of finding out what the limits for rider weight would be on road bikes? I'm guessing tyre's and cranks would be most at risk of damage/wear issue's?
The first parts that fail most often for clydes is the wheels. The cranks aren't loaded that much more with heavy-riders than light because of pedaling dynamics. The extra weight may be used to push down on one side, but that force is also being used to push the dead-leg and body up on the other side. So it balances out and the resultant net-force on the cranks is due primarily to muscle-exertion.
The frames can typically take 1200lbs+ before they bend noticably and 1500lbs+ before they take a permanent bend.
so wheels are the most vulnerable. You'll want heavy-duty 36-hole wheels built on strong rims. Then you're talking about 400-550lbs of load-carrying capacity. Tyre-pressure and size plays big role here to prevent pinched-flats. Used large 32mm tyres at 100psi+ to handle the load.
Minimum 32, better 36, if super clyde (400#+) then maybe 40 spoke rims
all of these with an 'aero' deep cross section are advisable. Super clyde
standing and honking up a hill may approach some crank torque limits,
and some pedal axles, but as noted by Dannoxyz, not in ordinary riding. http://www.peterwhitecycles.com/index.html is one source of heavy
duty wheels. Tandem wheels can handle 500# teams easily but the
rear hubs won't fit standard road bikes, the rims and spokes will
work with standard hubs.