The Mountain Bike Life

Ever wonder why they changed the design of bottom brackets so much over the last 10 years? What was wrong with the good old square drive axle? As it turns out a lot was wrong with it. The new through axle cranksets and bottom brackets are very rigid and require very little maintenance. Best of all they very rarely creak. That one sound that drives every biker of any type nuts. That loud creak every time you apply force to the crankset. It can ruin an entire ride which is otherwise great. Well if you happen to still have one of the older cranksets and it has developed a creak you can get rid of it. How? Read on…….


First let’s define the problem. The creaking is a result of the crank arm slipping forward and backward just a little bit. When the creak first start you may not even feel the slipping, just hear something. After time you may start to feel a little click on every rotation. That is the crank arm walking off the axle and getting looser and looser. In extreme instances the crank arm bolt will come loose and allow the crank arm to come right off. Probably the weirdest thing you will ever feel when going up a hill. Hopefully if it happens to you no injury will occur to anything other than your ego. 
 

Use your crank arm puller to remove the crank arm.

This slipping is from one of two things. Dirt or debris can get between the crank arm and axle when you put it together and not allow the crank arm to seat all the way on. Then a little gap forms and allow movement of the crank arm. Unfortunately if this goes on for a while the second cause of the creak will occur. This is wearing of the axle or crank arm itself. Replacing the bottom bracket is a quick and cheap fix. However this is usually not the problem. More often the crank arm mounting hole gets stretched out. When this happens the crankset is pretty much junk. I suggest going to a newer design at this point, but this may also open pandoras box of the parts purchase. The spacing on the crank arm rings of older 8 speed cranks is different than newer 9-10 speed cranks. Your existing front derailleur may not work and then you may need a new rear derailleur, then you need new shifters, then you need a new chain, possibly new wheels, new air fork, carbon seat post……..it will never end. Maybe you should just find a used crank on ebay that is still in good shape.

Once the axle is clean add some grease to it. 

Now that we have established the problem how do we fix it? This part is actually pretty easy. Take your handy dandy crank arm puller and (you do have one right?) pull the creaky crank arm. Once the crank arm is off clean the bottom bracket axle and the inside of the crank arm mounting hole. Get both as clean as possible. Next put a little grease on the axle. I use synthetic axle grease, but there are many lubricants that will work here.

Tools needed to fix your creaky crank.

Put on the crank arm and then gently tap on the crank arm with a rubber mallet, dead blow hammer or something plastic/soft. Don’t hit your crank arm with anything metal as it will dent and possibly stress out the mounting hole itself. Last step is just to put your crank arm bolt back in and tighten up. Easy! Go for a ride and enjoy a nice quiet ride. After a couple of rides you may want to retorque the crank arm bolt. If everything is still quiet you should be good for a long time.

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