Looking to upgrade my bike wheel bearings to ceramic but wonder whether they really do improve performance.
Ceramic bearings are, without a doubt, far more efficient than their metallic counterparts and offer significant performance advantages (the Quick-Step team always used them even though they were sponsored by Shimano and I think many pro-teams still defy their sponsors and use ceramics). The caveat to this is that pro teams can afford to replace bearings once a week- us mere mortals have far more important things to spend our money on (which I guess is the gist of your question!). Without knowing exactly how you intend to ride or exactly what your budget is it is very hard to answer the question- however unless you have a real performance machine under you (Sram |Red/Campag record kit etc) the chances are you will get greater performance gains, and far greater longevity from upgrading existing components- especially as the sealed units most manufacturers use are actually pretty good already. My personal experience is that most bikes can be improved very quickly and most effectively with a tyre upgrade and most riders can be improved most effectively by losing a few pounds! Both cost very little and both are very easy to do!
If you're asking this question, then the answer is probably no. Not because there isn't a tangible benefit to them, more so because you're probably not a strong enough cyclist to recognize the 0.5% improvement in efficiency. You're better off investing in lighter or more aerodynamic components, those will net you a far more noticeable improvement in performance.
Ceramic bearings are used where you need a very high heat tolerance or high speed. You won't find either on a bicycle. For the money you cant go wrong with stainless steel bearings.
If you don't mind spending a lot of money for a tiny benefit, go ahead. Just make sure that the bearings you plan to buy are actually better than the ones they are replacing. Some ceramic bearings are not really any better than steel ones. Drag from your bearings is a tiny fraction of overall mechanical, friction, and aerodynamic drag that slows you down. Improving your bearings might only give you a fraction of a percent improvement in overall efficiency
