In 2019 I bought a Wilier Zero6, their lightest bike specifically designed as a showcase for how light they could go at the time. The bike had an RRP of £11000 in the UK and I got it for £4900 new in the annual sales (due to its small size not selling)...it weighed 13lbs. Full carbon, sub-700g frameset and SRAM Red.
I've almost immediately increased the weight by adding ZIPP 303 wheels and more recently Wahoo Speedplay Powermeter pedals. I cancelled out the PM pedals additional weight over titanium by changing to Tubolito tubes. The bike is more aero than original thanks to the deeper wheel set and still only weighs in at 13.7lbs.
I also have a 17.5lb Trek Madone SLR.
The difference between them is very noticeable on climbs, especially steeper, longer climbs, obviously. The Wilier accelerates faster and is more agile, nimble. I also find it is more comfortable for longer rides.
The Trek carries its speed better on the flat due to being even more aero and I prefer it for sprinting.
The idea of a lightweight climber is a good one, in my opinion, since regardless of theory and what people who have not ridden very light bikes say, they actually do make a tangible difference to how you feel on a climb. My PR's for all my local long climbs are on my Wilier and my training partner has commented that I am faster on it than my Trek when we do a hills day; which is often, I live in a hilly area!
