I have a Trek 7.2 and have done the usual lightweight upgraded parts such as stem, bars, seatpost, fork, SLX cassette and tires/tubes. Ive seen a noticeable improvement at every stage of upgrade.

Now theres not much left to upgrade except for the wheels themselves, the bike now weighs 9.2kg....but OMG wheelsets are freaking expensive and im not looking to spend $500 for a pair of new wheels, sooooo....

If i were to rebuild the wheels with lightweight spokes, maybe even aerospokes and lighter hubs, it would run me about $150, which i think would be good enough. So my question is would simply using more aerodynamic spokes, or lighter weight double butted spokes and lighter weight novatec hubs with sealed bearings be worth it? Will there be a noticeable difference? How much does the rigidity of an aftermarket rim make, or does that also depend on the type of spokes that are used? Current spokes are 32 per wheel.

Thanks

I think if anything, I'd be focusing on lightweight rims, rather than lightweight hubs. Spokes are going to be basically the same weight. I honestly don't think it would be worth rebuilding a 32h wheel for the sake of lightness. If you're really wanting a nicer set of wheels, while saving some weight, for

No. Aero spokes are only worth 1W at 30 MPH and 0.5W at 20. It takes me about 200W to cruise at 20MPH, and 700W to reach 30 in a sprint.

Weight almost doesn't affect speed on flat ground, and up the steepest hills the change is proportional to the difference in total weight.

Assuming you weigh 62kg for a 71.2kg total weight saving 100g is only going to make you 0.014% faster and a full 500g just 0.7%. If you're 5-25 seconds away from breaking 1 hour in a hill climb those savings are worthwhile, otherwise they're not.

Accelerating the impact doubles as you approach the road surface, although that's still insignificant.