Sliding down when pushing the pedal

[DannyBoy_r]

Hello everyone!
Have a bit of a problem with my bike. I've decided to change my bike from multi-speed to a single speed. So i got myself freewheel 16 teeth 1/8", Chain Tensioner and single speed chainset (Sturmey Archer) 1/8" + bottom bracket 103mm that was added by seller. I've managed to put everything together, however this kind of problem came up:

When pushing the pedals - they are sort of slide down a bit - feels like chainset scrolling for a bit over axis with the pedal position on 3pm jumps to 5pm and after moving like it should till next pedal moving to the same position.

I am not quite sure what it is - any suggestion would be helpful!

Thanks!

[DaveM]

It this happens over and over, the only thing I can think of is that the front chainring is not tight to the crank arm. If you can look down while riding, see if the chain stops moving for a second as the crank arm keeps going around. Or find a mark on the chainring that lines up with the crank arm and see if that is changing after a slip.

Most single cranks have the chainring either welding or bolted to the crank arms. But sometimes there is a nut that holds them tight against each other.

[Painkiller]

cross check with another wheel see what happens, if it strolls it is in the freewheel.