How do I stop play in Bike bottom bracket?

fender

My mountain bike has play in its front sprokets/bottom braket.

How do I tighten it?

Thanks.

shandypants5

Depends what kind it is, some of them are not adjustable.

If you can see a large hexagonal part then it may be the old adjustable type and you can just snug it up a little.

If it looks like it has a "casselated" insert, then it is prob a cartrige type and will need replacing.

This page may help you.
http://www.sheldonbrown.com/tooltips/bbadj.html

boatman

It could be one of two things, either the crank is loose on the bottom bracket(normally tighten the bolt with an allen key on the crank arm) or the bearing in the bottom bracket is loose. If the bottom bracket is loose/failing you'll feel both cranks move. Look at this link it shows some bottom brackets.
http://www.edinburghbicycle.com/ebwPNLqrymode.a4p?f%5FProductID=0&f%5FWebLinkID=3226&f%5FSortOrderID=1&f%5Fbct=c003154c003151c003226
http://www.chainreactioncycles.com/Images/Models/Original/26067.jpg
http://84.19.224.75/products/full/00000193/00003022.jpg

Pew_Pew_Pew_Lasers!

Chances are the crank has come loose. Two reasons for this, one is just general use and it needs retightening, the other is that the ends of the bracket have worn. Doesn't happen a lot on square tapers (the old variety) but on more modern ISIS designs and similar it can be a regular occurrence.

If its a crank with external bearings then all bets are off