I like my bike
My grave bike has been with me for a year. Although I wasn't thrilled about it at first, I think I've fixed the most of the problems, and I can now state with pride that I like my new bike.
Buying a new bike with a drop bar was something new to me. I am not the fittest person, so I was afraid it would be uncomfortable to ride on it. While this is mostly true with the road bikes, gravel bikes are much better in terms of conformability. Yet, I still had back pains, hand numbness, and knee issues.
Home fitting
At this point, I did not see a point to go to the professional fitter. I am not that much of a Cycklist yet. I decided to do some research on my own.
The first thing to set up on a bike is the saddle. There are many techniques for finding the right saddle height. One of the simplest ones is to measure the length of the leg (from the crotch to the toe) and subtract 10 cm from it. This gives the length from the centre of the crank to the top of the saddle.
So I set the saddle to 75,5 cm (that's my number) and went for a ride, taking the allen/hex key with me. It is crucial to find a route with some flat parts, uphils, and downhils for this type of test. During the ride, I found it was slightly too high. I made some minor adjustments during the ride, and the final saddle height for me seems to be at 75 cm. I don't feel any knee pain since the adjustment.
The next thing to address was the hand numbness. I found out it is a common issue, and the advice is to change the position of hands on the bar. What? That is stupid. There must be something related to the amount of pressure between my hands and the bar. In comparison to the normal bike, I was leaning out much more, so my weight distribution was moved to the front. While so much weight rests on my hands, blood flow in my hands could be disturbed, hence the hand numbness.
I had two options in my mind. Change the stem to a shorter one, or raise the handlebar. Changing the stem has two disadvantages: price and controllability (with a shorter stem, bikes tend to be oversteered). After some searching, reading, and asking others, I decided to change the drop of the handlebars a little bit up - not more than 1 cm. Went for a ride, and it works. No more hand numbness. No more back pain. Success.
I know the above changes may not be what some professional fitter would recommend. However, I am listening to my body, and it tells me I did the right thing.
Summary
The end of the season is near. I completed 1700 kilometres and 68 rides. I rode 100 kilometres without experiencing any knee or back pain. I have thoroughly enjoyed every ride this year. I gained some muscle, dropped some weight, and travelled to a lot of new locations. Thanks, bike.