Back in october, I decided to train for hill climb so, I looked at my parts bin and things I could swap. I decided to see how light I could make the smooth hound on a budget. So I stripped it a rebuilt to the following spec.
I fitted "old" gravel bike parts, namely: Stem, handlebars and seat post.
The transmission is a big mix of what I had in the garage: Shimano Sora 9s brifters RT3500 (side shifter cable) and Sora 9s "small cage" derailleur coupled to a Shimano XT 11-34 cassette because it is lighter than the Sora equivalent (235g vs. 450g) and has the same weight are a ultegra 9s 11-28.
A Praxis carbon crankset with Sram force1 50T chainring. It is also fitted with a 4iii power meter 
Front brakes are mini V brakes and the rear kept the Dia comp dual pivot caliper.
Kinetix pro front wheel and Frog team sky rear wheel. I initially used kojak 35-406 tyres
The bike weighed 8.3kg with the "big" cassette, "big" chainring, Frog wheel, Kojak rigids and butyl tubes.
I thought the the Hill Climb version would have a "small" cassette and "small" chainring (-135g), Kinetix pro rear wheel (-330g), Revoloop Race ultra tube (-120g), spider saddle (-150g)
Since then, I rode 1500k and had a crash in the snow which wrote or the shifter, bent the derailleur hanger and caused minor damages to the derailleur... it looked like that 5min before crash.
The current version is fitted with pedal ES600 (-250g)which are light, comfortable and , Ritchey Venturemax comp handle bar with later Sora RT3000 shifter (look like 105 with shifter cable at the back by the brake cable). I fitted a superstar component headset (light MTB kit) because the Tange kit was dead due to low quality bearing and for some reason, the fork was fitted with 2 crowns preventing the frame to seat properly on the fork under load.
I am waiting for a set or litepro aero wheels too.
I ride faster, the bike received continental contact urban tyres which are heavier (+ 100g for both) but have a rolling resistance of 16.4W per tyre vs 24.8 w for the kojak. The gain from the continental is mega noticeable (i ride able 5kph faster and have to produce 10 to 20W less).
i d like the whole Hill climb racer to be ~7.2/7.4Kg but I might be a tall order so I will see what can be done
It should be noted that a classic hill climb bike with a weight between 7 and 8kg costs more than £3000 minimum (700C wheels and carbon frame)
The goal of the project is to see if I can build a "competitive" bike for the cost of a "budget" bike; As wheel weight is a major factor, going with 20" sport wheels could be an advantage. So far, the total build would cost less than a pair of carbon Hunt wheels ("would" because I had most on the parts on hand).