Today new parts came and I did put everything together, took 3 hours, my first ever:
Chain swap
Rear gear install to hub
Front gears, cranks swap
New parts are all gears, chain, cranks, triathlon bar, rear wheel + hub, rear tire and pedals.
Front tire and wheel assembly is new for this bicycle, I recycled parts from one older bicycle, which had new tire and straight front wheel.
Even brake pads are new and everything is serviced and lubricated.
It was wet weather, bit of fog/mist kind of rain, wind was almost the same as before, maybe bit less gusts.
Might be that my legs were not working quite perfectly after long bicycle installation session, also I had one 9km quite fast trip on my belt for morning, uphill speed was certainly less than before, legs had no fire in them and I took my time to adjust seat height at the beginning of the trip, total time was similar than with grandmother bicycle, but on level ground with tailwind I could easily keep up 40kph speed, 30kph was child's play, where before that was limit with this bicycle and old gearing, crank rpm became too high that limited speed, but now that was not an issue, there was always bigger gears available. I could reach 53kph but felt that there would of been much more if my legs would not been so numb.
However wind seems not to go around me as well as it did with grandmother bicycle, perhaps handlebar should be lower, but then again it is at lowest position already, pushing head down I could feel wind easing up it's grip around my ears as wind noise did go lower and turbulence I could feel got lot less, so I guess that position is still bit too much upright and head pokes up into airstream instead of being level with torso and being at low velocity area.
So speed is around 10kph more at level ground now and gearing is plenty to support that, so it is step to right direction already, but need to try and see if I could improve from there, aerodynamic panniers to rear is something that refuses to let off from my mind, so I guess that is one thing to experiment with as my current panniers are bit small for all the stuff I need to haul from shop (like cat sand) so it would serve another purpose as well, I have tools and materials for making those from thin metal as they need to be rather strong, only thing I lack is skills, but those came when one fails enough many times, which means I must attempt to build something like that soon
edit: Today I found flat tire, well it did last 8km or so.
Put new tire in so that I could visit a shop, initial impression was that it did roll more freely, however again I felt that it was harder to go speeds that I did before, surely there was bit of head wind too, 30kph and as I did rode 10kph or bit more that worked out as if I would of cycle 40kph.
When coming back I did cycle 2km distance with average speed above 40kph and 2.5km distance with average speed above 35kph. Can't really tell much from performance, wind is messing things up greatly, but somehow it feels slower than it should be when climbing and riding against the wind. Forecast tells again that tomorrow should be less windy, let's see how it really is, but tomorrow I plan to do standard test route again, maybe I can get gps with me and do coast down test if there is zero wind, it might give some information about rolling resistance.
Should be easy to maintain 25kph travelling speed and should be no trouble climbing 15kph or more on those not so steep hills, top speed should be around 60kph, however must wait and see results to know.