Help with a 2002 trek 820 crank

[spiderjason]

Hi, I have been searching the internet for info with no luck... My 2002 trek 820 when I am pedaling is skipping real bad... Especially when I am going up an incline... I turned the bike over to inspect and I grabbed both pedals and pulled them back and forth an it is loose in the hub area where the bearings are... I probably need to replace my bearings... Can anyone tell me the tools I need and maybe step by step instructions on how to do this job? Any tips would be appreciated... I'm sure its not to difficult to figure out but I like instructions before I start a projected... Also, can anyone tell me the bearings I need to buy for my 2002 trek 820?

[supersedona]

That is likely going to be a Cartridge bearing assmebly "bottom bracket" such as a Shimano Un-51, square tapered spindle. To replace it you will need a crank arm puller like a Park CCP-1 and a Cartridge bottom bracket socket, which is splined to match the unit. Fortunately none of the tools in question nor the part are expensive or hard to come by.

One piece of advice though, is to get the tools and pull your current one out to take to the shop to size because the come in several measurements. There is a chance that the unit could be rusted in place from time so it may be a good idea to shoot some penetrating oil on the threaded shoulders a day or two before trying to extract.