where I live winters usually are -15°C to 5°C. For MTB I wear sports base layer and fleece jacket, but problem is wind goes right through making stomach and chest area very red and painful. I have a cheap windproof jacket, but it's unbreathing and sweat condensates on the inside, so stopping even for a short time in those temperatures while wet is dangerous for health. Wearing base layer + fleece + backpack i don't feel cold at all. All I need is something windproof in the front and still very breathable. Would cycling gilet/vest/waistcoat be sufficient? Are their fabric windproof? Maybe long sleeve windproof jacket is better, but are they breathable? Or maybe loose fleece at all and go with something else like softshell jacket? Please share your experience.
We are very fortunate that over the last 10 years there has been a lot of progress with technical fabrics, and now as riders we have a massive range of clothing to choose from.
Windproof materials come in a massive variety from very thin single layers of densely woven fabric to complex 3 layer fabrics containing a membrane, and often with water repellent treatments (DWR) sprayed on the outer facing layer. Many manufacturers make use of the Gore Windstopper fabric, however there are some excellent lesser known fabrics too.
The exact solution chosen is very much individual preference. Some riders run hot, others run cooler. Some like flexibility with layers and don't mind to faff a bit, whilst others prefer a solution is easy. You need to find the combination of windproofing and insulation that works for you, whether that is a fleece + light gilet, a fleece lined softshell, or multiple base layers under a thinner shell.
For me, when riding the mountain bike in freezing conditions, I like a long sleeve merino base layer, a jacket with windproof front panel and fleece back. I then carry a thin waterproof shell and a primaloft padded gilet in my backpack in case I need extra insulation or rain protection.
Specific product recommendations are off topic on this site as they tend to become obsolete quickly.
There are plenty of breathable windproof, cycling specific jackets available and reviews are easy to look up.
Wearing a wind-permeable fleece on a bicycle in cold weather is less than optimum because cycling always involves wind (although you are moving relative to the air, rather than the wind moving relative to you.
When you add a wind-proof layer to your fleece you are probably over-insulated and get sweaty when riding, then cold when stopped. Try a thinner insulating layer, and open zips etc to get some ventilation when working hard and avoid over-heating.
Another option is to block the wind inside the fleece. It does reduce the insulation of the fleece, but not by much. I'm not saying you need to go to the lengths of cyclists in the old days putting newspaper up their jerseys, but any windproof layer would do it.
In the past I've seen some (not specifically cycling) fleece gilets with soft shell or showerproof front panels. They'd be ideal.
Even a tightly woven fabric helps a lot (down to about 0°C I'm OK with a short sleeve jersey under a long sleeve except for sustained descents).
The problem is the backpack. It will keep your back h and sweaty, while the rest of your body is cold.
If you could use a panier or a bike packing saddle bag, you could just wear an all around heavier windproof coat with pit vent to let air out.
I've not seen a winter cycling jacket with a lighter back and a heavier front side.