Square Tapered Crank Removal

Square tapered cranks have existed for a long time, and the vast majority of bikes used to use them. Many still do, and I can show you how to remove them in case you need to service the bottom bracket or replace a chainring or whatever. First you need a crank puller, you really can't remove a crank without one (well technically you can, but you won't be able to reuse it..). You will also need a tool to remove the crank bolts, and these are usually on pretty tight so you'll want something with leverage. Crank bolts are usually 14mm hex or 8mm Allen bolts, and I've even seen 15mm hex ones too. That's about it as far as tools are concerned. Let's get started:

First pry out or unscrew any dustcaps covering the crank bolt:

Remove the bolt (or nut in this case). I have a pedal wrench with a 14 and 15mm socket attachment on it that I like to use for these, otherwise a ratchet with the correct sized socket works nice. Once you remove the bolt you will see the bottom bracket spindle and the square hole around it:

Now it's time to use the crank puller. First you thread the puller all the way in so that it's engaging as many threads as possible. Start by hand to avoid cross threading it, then use a wrench to turn the puller all the way in. Don't tighten it once it's done, just leave it snug. Next you will turn the puller's handle to force the crank off. There will be lots of resistance at first, but once it gets easy to turn you can slide the crank off.

 

Here is a type of crank puller without a handle. You use it the same way as the Park Tool puller shown above, but you need to put a wrench on the top part. I like these since you can put a ratchet on it and just turn it without worrying about the pedal interfering.

Here is the bare spindle after the crank was pulled off:

I like to clean the flat parts of the spindle and put a very thin layer of grease on them so that the crank slides back on correctly (grease is optional). To reinstall the crank you just shove it onto the spindle, then tighten the crank bolt to push the crank onto the taper. You need to turn the bolt a lot at first, even after you start to feel resistance because the crank has to be pushed back into place by the bolt.

Don't leave the bolt loose. I think the torque spec is at least 25 ft-lbs which is pretty substantial for a bike part. If it's too loose the crank will get rounded out as you pedal, so make sure that bolt is very tight. After all that you're done. You should never retighten crank bolts if they were tightened properly the first time. This tutorial is also useful for splined cranks like Octalink or ISIS, you'll just need a wider attachment for your crank puller.

Adjustable Bottom Bracket Service

Today I regreased the bottom bracket on my 40 year old Dawes Lightning. It was probably the nastiest looking bearing I've ever seen, with lots of dirt and dried up grease all over the bottom bracket shell. I took some pics too so I'll show you how to service the old style bottom brackets in this little tutorial.

First you need to remove the cranks. This bike uses cotter pins, so you can read my earlier post on cottered cranks if yours are like this one. If you have square tapered cranks you just remove the crank bolts and then use a crank removal tool to slide the crank off the tapered spindle. Also if you're replacing your cottered cranks with square tapered ones you won't have to replace the entire bottom bracket, just the spindle.

 

With both cranks removed it's time to take the bottom bracket apart. First remove the lockring on the adjustable cup. This will be on the non-drive side. I used a little tool with an adjustable pin on the end of it, but there are also bike specific lockring tools available. If you're working on a beater bike then you can just use a vice grip or a hammer and punch if you don't want to buy a proper tool.

 

Here is the lockring removed. The next step is to unscrew the adjustable cup. These usually have wrench flats where you can put an adjustable wrench on, this particular one just has little holes to put a pin spanner on:

Once the cup is off you can slide the spindle out. Keep track of any ball bearings that will inevitably fall out.

The last step to disassembly is sort of optional. You will need a big wrench to remove the right side cup. This is also called the "fixed" cup since it is screwed tightly into the frame and can be difficult to remove. If you choose to leave it in it will be much more difficult to clean the bearing surfaces, which is why it's "sort of" optional. Anyway you remove it with a big wrench on the two flat sides of the cup:

Now if you have an Italian or old French frame you will just unscrew the right side cup normally (counterclockwise). If you have anything else (British, Japanese, American, etc.) you will actually have to turn it clockwise because it will be reverse threaded (just like a left side pedal). If the cup is hopelessly seized in the frame due to rust then you might have to stick the cup in a bench vise and use the entire frame as leverage to unscrew it. Fortunately I didn't have this problem so here's the empty bottom bracket shell:

Clean every bearing piece as best as you can:

Now grease the cups and stick the ball bearings in. Having a nice thick grease will keep everything in place. If you have bearing retainers make sure you put them in the correct way, usually with the smooth side facing the cup and the jagged side facing upwards.

Now clean the threads inside the bottom bracket shell and add some grease to them before screwing the cups back in. Screw the fixed cup all the way in first, but don't tighten it just yet. If your wench slips you could knock the balls out of place so I like to wait until the adjustable cup and spindle are installed.

Pay attention to which direction the spindle goes in. It will usually be longer on the right side to make room for the chainrings. Anyway once the bearings are loosely installed you can torque down the fixed cup. I don't think you can overtorque it with normal hand tools so just make it as tight as you reasonably can, and be careful to not get hurt if your wrench slips.

Now it's time to adjust the bearings. Screw the adjustable cup in until the play in the spindle disappears. Then you can install the lockring.

After tightening down the lockring check for any play in the spindle. If there's play then you have to loosen the lockring, screw the left side cup in a bit more, then tighten the lock ring. It's sort of a trial and error process. Sometimes the bearings will loosen a bit by themselves from the force of the lockring, so you might have to overtighten them at first to compensate. I like to overtighten them just a little bit anyway since these adjustable bottom brackets tend to loosen up a little during use. If the bearings have no play and don't bind up as you turn the spindle you can consider it done. Just reinstall the cranks and enjoy your freshly greased bottom bracket.

Modern Rear Derailleur Overhaul

Newer rear derailleurs are usually trouble free. Sometimes they get gummed up and might not spring back like they should. Or more commonly the pulley wheels stop turning freely. Here's a tutorial to take one apart and reassemble it. The derailleur shown is an older Shimano Light Action unit, but it's similar to other Shimano indexing derailleurs.

First you need to remove the tension pulley. Usually this is an 8mm hex or a 3mm allen bolt.

Now remove the guide pulley. I often just spin the cage plate counterclockwise to loosen the bolt rather than fuss with a wrench. Keep track of each pulley and its parts. The top pulley is different than the bottom one and shouldn't be switched.

Now clean the pulleys and the bushings well and reassemble them with oil. They should spin freely.

If the derailleur's springs are working fine you can just reattach the pulleys and stop here. Otherwise it's time to remove the remaining cage plate. This particular derailleur uses a 6mm allen bolt to hold the pulley cage knuckle together. Most derailleurs instead use a long slender 2.5mm allen bolt to keep the pulley cage in place. In either case, unscrew the bolt and the cage will pop right off.

 

 

With the cage plate removed you'll see a spring and a plastic dust shield. Clean these as well as the inside of the knuckle. Your derailleur may have 2 holes on the plate you removed which the spring attaches to. If your derailleur is worn and the chain tension is low, or you just want maximum chain tension to prevent it from falling off, use the stronger setting when you reattach the cage. If your tension is fine then use the weaker setting for less drag (this is usually the factory setting). 

Now you can also take the B knuckle apart. I really only suggest doing this if your derailleur is very old and dirty, or if it won't maintain an even chain gap between the top pulley and each gear. The backing plate can be very difficult to reattach since you have to fight the spring's tension. This doesn't apply to Sram derailleurs though, since there is no spring in the B knuckle to worry about. Anyway, first you have to pry out the C-clip:

 

 Now remove the spring and dust shield, and clean them. If the top bolt doesn't slide out or turn easily then it's probably bent, and this might cause an inconsistent chain gap between gears. If this is the case I would suggest clamping the bolt in a vise and bending it back with an allen key. If it doesn't come out but at least turns easily then don't worry about it and just squirt some oil in it. Here is the B knuckle taken apart:

Ok now it's time to put everything back together. First pack each knuckle with grease and reinsert the springs. The springs need to catch a small hole at the bottom of the knuckle. Rotate the spring until you feel it catch, then push it down into the hole. Try twisting the spring some more to make sure it's locked in place. After this you can put the dust shields back in place.

Now comes the hardest part. You need to rotate the B knuckle's backing plate against the spring's tension until the plate's tab is behind the derailleur's stop. Then you will need to push it down and hold it in place as you slide the C-clip back on. I can sometimes do this by hand, most of the time I need to wedge a small screwdriver between the backing plate's tab and the mounting bolt and twist until the tab is behind the stop. I like to use pliers to hold the backing plate in place once you twist it far enough. Once you get the C-clip in place then it's locked together and you can relax.

Now you can reattach the pulley cage. It's probably easier to reattach the pulleys and assemble the cage before attaching it to the rest of the derailleur, but I like making things harder for myself for no reason. Anyway with the spring and dust shield secure you can slide the end of the spring through one of the holes on the cage plate. Note that the spring has one end that's a smaller diameter than the other, the smaller end goes into the pulley cage. Next you will rotate the cage against the spring's tension until the plate's stop is behind the tab on the knuckle. This step is much easier than the last one since you can use the entire cage for leverage. Once the cage is rotated behind the stop you can push it all the way into the knuckle and secure the bolt:

If you didn't already assemble the pulley cage you can attach them now. First install the guide pulley (this one usually says "Centeron G-Pulley" on it):

Now rotate the second cage plate and add the tension pulley:

Make sure all the bolts are nice and tight, and then you're done!