Hurting knees can be due to riding in too high a gear.
Another common mistake is having the saddle height too low, forcing you to bend the leg too much and putting more stress on the knees to move the pedals down.
Even a few centimeters (~5cm) can make a big difference, but it will feel strange at the beginning and it take some rides to get completely accustomed to the different movement.
I found a dropper post to be a great help with that. It’s much easier to figure out the right height while riding and not having to dismount to adjust it. And anecdotally, it sometimes feels better to adjust it up or down by 5-10 millimeters, maybe due to different clothes or shoes or posture or surface grade.
Note: even the cheapest dropper posts costs around 100 euro (from a cursory Google search). People who aim for cheap bikes often don’t consider them. If you can afford it, consider if it would be a small investment into your comfort and longer-term health.
Another common mistake is having the saddle height too low, forcing you to bend the leg too much and putting more stress on the knees to move the pedals down. Even a few centimeters (~5cm) can make a big difference, but it will feel strange at the beginning and it take some rides to get completely accustomed to the different movement.
I found a dropper post to be a great help with that. It’s much easier to figure out the right height while riding and not having to dismount to adjust it. And anecdotally, it sometimes feels better to adjust it up or down by 5-10 millimeters, maybe due to different clothes or shoes or posture or surface grade.
Note: even the cheapest dropper posts costs around 100 euro (from a cursory Google search). People who aim for cheap bikes often don’t consider them. If you can afford it, consider if it would be a small investment into your comfort and longer-term health.