# How do you adjust the crankset/BB on a kid's 12" bike?



## djork (Nov 8, 2004)

The other day I noticed the crankset on my nephew's Specialized Hot Rocks was loose. Well, the cranks wasn't loose but rather BB came loose. On the non-drive side there is a flat nut that uses a wrench to tighten/loosen, followed by a big washer, then the bearing retainer. Apparently the nut came loose and with it the washer and the bearing retainer. It looks like the bearing retainer uses some speacl tool to tighten it. There are two notches that I used as a hold for a flat screwdriver to slowly tighten. Then I used an adjustable wrench to tighten the nut. I noticed that too tight and the cranks don't turn smoothly, so I tightened it just enough that the nut held the bearing retainer and loose enough that it spins smoothly.

This is more of a temporary fix because I'm not sure if I fixed it correctly. How tight should the nut be? Have no idea when the whole thing came loose. Is this normal?


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## bme107 (Jul 23, 2008)

Is this what you're dealing with?
http://www.parktool.com/repair/readhowto.asp?id=92


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## Dad Man Walking (Sep 7, 2004)

Sounds to me like you figured it out. There's not a lot to those one-piece cranks, and in my experience they come from the factory (and the department store) poorly adjusted. Way too much preload on the bearings on every one I've worked on. They adjust like most other bearings...you get the preload just right on the inner cone/race/nut, then hold it in place with some sort of tool (pin spanner or something like that) while you tighten the compression/lock nut on top of it. Then do it over 3-4 times until you get the bearings to run just right.

The only thing I'd suggest taking another look at is how tight you got the lock nut. You have to have the right tool (or a good substitute) to hold the adjustable race (or cone, or whatever it is) so that you can crank down on the nut without over-tightening the adjustable race/cone thingy. Just loosening the outer nut to back off on the preload pressure usually won't do the trick, it will just come loose again..


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## Mount Dora Cycles (May 29, 2009)

I usually tighten the bearing race (the one with two slots) down tight enough to where the cranks barely spins. then install the washer, then the lock nut hand tight. while holding the lock not use a screwdriver to back out the race against the lock nut and this usually give just the right amount of load on the bearings to turn smoothly and makes it so they won't come loose again.


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