Bicycle making cracking noises

VonLuck

Hoping someone can help me with a sudden problem I have with my hybrid bike, which is about 5 years old now. I was cycling along as normal, regularly stopping at red traffic lights in the city. Typically when I start off from a standstill I stand up to get the initial speed up. Yesterday when I did this, there was a sudden cracking noise coming from the bottom bracket. It seems to keep occurring whenever I stand up on the bike.

Since then I noticed the chain rubbing against my front derailleur once every rotation (i.e. not continually rubbing). The chainset seems to be off vertical and almost wobbling as I pedal, causing the chain to rub against the derailleur.

Any idea what might cause this? Is it likely that the bearings are gone on the bottom bracket? I tried tightening the chainset just in case it came loose, but it wasn't budging so assume it's not that.

magicbastarder

i'd suspect something has popped in the bottom bracket by the sound of it if it's wobbling.

is there any play in it? i.e. do the cranks feel loose if you try to wobble by hand?

if it's just the BB, they're not horrendously expensive to replace, your local bike shop would be able to replace it easily enough.

VonLuck

https://boards.ie/discussion/comment/117618379#Comment_117618379

There is a bit of play alright. I figured it was the bottom bracket. Probably overdue a replacement. I may bring it in for a service and get everything tightened up.

Could dirt have a part to play in wear and tear? I haven't been able to clean the bike in some time, and the bottom bracket is caked on with dirt at the moment.

magicbastarder

generally they're well sealed, and five years would be a decent bit of use out of a BB if it's a bike you use often.

one of my LBSes have a sign up saying they levy a €10 surcharge on bikes dropped in for work, which they have to wash before they can work on them!

VonLuck

To be honest I'd be happy to pay €10 for a good wash! Apartments aren't the best place for a dirty bike.