Bug: The quest may disappear from the quest log after doing The Isle of Mists, Radko will also become impossible to interact with. However, the issue should fix itself after completing Something Ends, Something Begins as the game will return to the state prior to going to the Isle.
The quest can be started by checking Crow's Perch's notice board. Head out to where the racing starts and talk to the race coordinator, Radko, to start a race against one of the contestants. There are a total of 3 different races you must complete against the following people:
Note that each race will "jump" ahead in time to 11pm, so if you do them back to back, you'll jump ahead by 3 days. It also doesn't matter which order you beat each competitor, but once you beat one, you can't race them again. Each racer will also give a set amount of crowns and horse equipment (i.e: even if you race Stuttering Mattko last, he'll still give the saddle and 20 ).
The race course is simple enough: just follow the black line on the mini-map, which will go through part of Blackbough and take a sharp turn, over a bridge, and then a pretty straight line to the finish. Like any race, going off course too drastically and/or skipping checkpoints will fail that race and you'll have to re-try.
Also, there are two random obstacles that can appear but you'll only face one of them during a single race, if any. The first is some loose barrels right after the first curve in the course. You'll know if it's coming if time slows down. If that's the case, move as far right of the path as you can get and this should line you up to go right by them without slowing you down. Time will resume as normal right as you pass them. The second possible obstacle is simpler: soon after the bridge you may see a log laying across the path. Most times, Roach will automatically go towards the small opening on the left of this log and continue along the course without any trouble.
When racing Stuttering Mattko, he's considered the easiest of the three as he'll never have an obstacle appear when racing. Once beaten he will give a racing saddle along with 25 and an extra 20 on top of what you wagered.
Iron-Arse Hans is generally the intermediate racer and, more often than not, an obstacle will appear when racing him. When beaten he gives the saddlebags along with 25 and an extra 30 on top of what you wagered.
Black Bogdan is generally the last one to be raced, but obstacles may not show up when racing him. When beaten he gives the horse blinders along with 25 and an extra 40 on top of what you wagered.
- There was not much in the way of entertainment at Crow's Perch, so the baron's men were always looking for new ways to pass the time. One of their favorites - horse racing at night and the chance for friendly (and not-so-friendly) betting that went along with it. Though the witcher had plenty of other things to occupy his time, he decided he could spare a few moments to take part in these races.
- Geralt was the first to ride past the finish line - which should come as no surprise, given all the time he had spent in the saddle and the fact that, unlike all the other participants, he could see in the dark. The baron's men expressed their admiration for his equestrian prowess (thought [sic] perhaps not in those exact words) and encouraged him to join them again some other time.
- Get to the race's starting line.