Cranks slipping - trying to work out why
A few weeks ago the cranks on my hybrid commuter bike (3x8 speed Shimano, 28-38-48 x 11-31) started slipping, by which I mean that sometimes when pushing with moderate to hard force they would suddely rotate forward through maybe 60 degrees with little reistance, accompanied by a clicking/crunching noise.
I did the following things, with no change:
- checked alignment of rear deraiilleur
- replaced chain with a new Shimano HG50 8 speed
- replaced cassette with a new Shimano HG50 12-25 8 speed
The problem is getting steadily more frequent but is still intermittent enough to make it hard to diagnose.
Does anybody have any suggestions as to what the problem might be? I have tried to look and see butwith no luck, as it only happens when under pressure that means while I'm riding, in which case it's inadvisable to be staring down at your drive train rather than at the road and cars around you. My best guess is that maybe the freehub's ratchet mechanism is has developed a fault, but I don't even know whether that ever happens.
If all else fails I'll take it to a bike shop but I'd rather fix it myself because that'll mean less time without the bike.