Originally Posted by
nrsmd
Assume tires with a rolling resistance of 20 watts. Now replace with tires with a rolling resistance of 10 watts. What speed increase, if any, can I expect all things being equal?
All things won't be equal as the "faster" tyres will be lighter and probably more supple and have a better road feel. Speed difference is a bit of a "piece of string" thing. What's your current speed? Or speed over a 25-mile time trial? Saving 10 watts over a time trial would certainly be noticeable! Just casually riding around or on a café club ride? Not so much. Still a worthy upgrade though.
Originally Posted by
nrsmd
Now, what if I purchase aero rims.? Will I get a measurable boost in speed adding carbon fiber rims (assume cost about $400-$500 for the pair of rims)?
Assume going from shallow box section rims to some 60mm deep aero rims, you'll definitely notice a difference! It's most noticeable in the ability to hold that higher speed and carry it for longer. In my testing over a 10-mile time trial, simply moving from shallow to deep wheels on the same road bike netted me about a minute over the course for the same power output.
Deep wheels won't make you fast, but they'll make faster easier.