If the crank is slipping around a square taper BB or splined BB you are fscked. Replacement time.
If it's something else in the driveline you can fix it.. maybe loose sprocket, loose lockring - does it slip after you've applied backward pressure? Oh, is it fixed or ss? DETAILS PEOPLE! It could be your freehub pawls not engaging but we don't know because you forgot fixed, ss, geared.. etc.
(don't mind me.. late night, early morning)
If the crank is slipping around a square taper BB or splined BB you are fscked. Replacement time.
If it's something else in the driveline you can fix it.. maybe loose sprocket, loose lockring - does it slip after you've applied backward pressure? Oh, is it fixed or ss? DETAILS PEOPLE! It could be your freehub pawls not engaging but we don't know because you forgot fixed, ss, geared.. etc.
(don't mind me.. late night, early morning)