Bicycle Mechanics - Crank problems

Ok lets start off with not repeating a mistake. My bike is BMX. Now I have a 3-piece crank and after pedaling for like a mile or so, the crank starts to come loose right next to the bearings. Now believe me that I know how to put a crank on but I was just wondering if the tightness of the chain or what condition your bearings are in would have anything to do with that? Any help would be appreciated.

If the crank is getting loose on the spindle, then the chain tension or bearings are not the problem. Is this the style with a bolt that pulls the crank on and a pinch bolt to keep it tight or is it splined like a profile?

If you have ridden with the crank loose on its spindle, you may have damaged the crank so that it can no longer be secured properly. Because both crank-fixing blts are clockwise-threaded, it is slightly more common for the left crank to work itself loose, but either side can be affected.

Ok, its not the crank arms that are coming loose. Those are extremely tight so Im pretty sure thats not it. I have old fashioned ball bearings. I'm not high tech enough to understand exactly what a spindle and all that is though. Please explain. Thanks.

Yes sorry to break it to you but you proboly need a new crank. I had the same problem with my trek tr-10. I rode on it when it was loose and afetr that tighetning it did no good and it still was loose so I had to buy a new 3 peice crank.

Go to Pep Boys or Auto Zone and get some blue locktite (the non-permanent kind). Clean your bolt real well, apply some loctite, put it in real tight and go ride.

It sounds like you have a traditional ball and retainer bottom bracket with a key way washer and locknut. If this is correct it sounds like the bottom bracket is not adjusted correctly. You must get the "slop" or side to side play out of the b.b before you tighten the b.b up but not so much it rotates rough. Then put on the crank arms. Also if it stil comes loose then the lock nut could be stripped ot the bearings are in backwards. The retainer needs to face out with the balls facing in.

Ok, I'm gonna tell everyone whats wrong here just so you all know. And this will be in a form such as everyone like me that do not know all the complicated bike words would put it in. This may get a little confusing. Ok, first off, my bearings were super bad. I had to get brand new bearings. I was surprised because I dont ride that often or that hard that I feel I would need new bearings on my crank. Second, the two cup-like pieces that are on each side of the frame, in the frame, that hold the bearings, they were completly gone and by gone I mean they had many, many cracks in it. So basically instead of a cup shape, they looked more like a straight pipe with cracks in the side. I've gotten it all taken care of and am now having almost no problems with my bike. If anyone who takes a look at this and knows the names of the cup thingys that Im talking about, feel free to post it. Thank you for all your help. This is a great bike site.