crunching when pressure on pedals

[matsaul]

My chain derails when I push through for some power. Make a crunching noise before it re-attaches to the front cog. This does not necessarily happen when changing gear, so I am not sure if the problem is chain or derailer.

Anybody had a similar experiance, offer guidance? thanks for any feedback.

 

[SimonC]

Either the chain is worn, the cassette is worn or probably both.

Swap the lot, either DIY or take it a bike shop if dont have the tools or knowledge.

Parts will be about £40-50 for a decent chain and cassette. Labour no idea, I fix me own bikes.

 

[SimonC]

Just re-read your post properly!

You say it derails from the front chainwheel when you press down hard and then jumps back on. Maybe its slipping on the chainwheel - has happened to me, I fitted a new chainwheel and it was sorted, and as a temporary measure I put the chainwheel on back to front so I was using the other side of the tooth profile if you know what I mean.

Have a look at the chainwheel teeth, if they are really pointy, thats probably the cause. Try putting it on back to front and if it doesnt slip theres what you need to swap.

 

[matsaul]

thanks for your reply

thanks for your reply