How To: Fit Bb, Cranks & Pedals

[TomR]

How to:

Fit a bottom bracket, chainring, cranks & pedals.

What you’ll need:

Bottom bracket tool (Make sure it clears the washer on your BB if there is one, I had that problem)

Socket Wrench/Torque wrench

8mm allen key/socket bit for the wrench

5mm allen key

Mole grips/pliers

Grease

Method - BB:

While it’s in pieces, clean the threads up best you can, and old toothbrush and some white spirit will do fine.

Taking note of the L and the R indicating the orientation of the BB in the frame take the threaded collar and put a blob of grease either side of it, don’t bother working it into the threads, it’ll do that itself when you screw it in. The left hand (non-drive) side is a regular thread, meaning you turn it clockwise to do it up. Screw it in half-way by hand.

Note: When screwing things in, especialy into anything remotely expensive, turn the bolt/nut/collar/cup as if to undo it until you hear the start of the threads drop into place with a small 'click' before you proceed, this'll help prevent crossthreading it.

Take the remainder of the BB unit and grease the threads, screw this in fully and tighten with the wrench and BB tool, Drive-side is a left hand thread, turn it anti-clockwise to do it up. If it starts getting stiff, wind it back several turns and repeat. If you know the recommended torque settings, torque it up, if not then do it as tight as you can with the socket wrench by hand (note: by hand doesn’t meaning leaning all of your weight into it or jumping up and down on the end of it). Now this is in, tighten the other (non-drive) side.

Method – Chainring:

Put the chainring over the spider and push the back of the chainring bolts through. If theyre too long, do as I have and find some washers, grinding/filing a flat on one side so they don’t foul the step on the spider.

Note: Be careful if you use a grinder, it’s very easy to let go of a washer and get it jammed down the front of the wheel, and trust me, you don’t want however many thousand RPM of grinding wheel hurtling towards your gonads. That’s before you even consider slipping and grinding your fingertips – best use some mole grips/pliers.

Grease the threads and screw the bolts in. You should be able to tighten them all the way up without trouble, but if they start spinning in the back, get the mole grips/pliers.

Method – Cranks:

Get a blob of grease on your finger and smear it on the splines of the BB axle (this will stop it creaking/seizing up) then put the crank arm on the axle. Grease the threads on the bolt and screw it up. Repeat for the opposite side making sure they’re in line with each other.

Now they’re both on you can tighten them up. These had the torque settings on the bolt seals:

32-35 ft/lb

43-48 n-m

421-470 kgf-cm

If you don’t have a torque wrench, do them as tight as you can with an 8mm allen key.

Note: Don’t forget when you’ve finished with the torque wrench to wind it back to zero else you’ll constantly be keeping tension on the spring and it will become inaccurate with time.

Method – Pedals:

Again, these have an L and an R on the ends of the axles as they have different threads for each side. Non-drive side is a left hand thread.

Put a blob of grease on the threads (as with just about everything in this how-to) and tighten the correct way. Do them nice and tight, you don’t want them falling off – and honestly, how often do you actually check your pedals aren’t coming loose?

All 3 piece cranks (crank arms being a piece each, axle being the third) the threads are 9/16”, 1 (and I think 2 piece) cranks as found on cheap BMX’s generally have ½” threads, Just in case you’re reading this and about to put your old MTB pedals on your cheap BMX run around.

Et voila!

Cheers to Adam@TartyBikes.co.uk and Trials_punk182 for the corrections and additional info .

If anyone spots any errors or has a better suggestion on how to do something, PM me and i'll edit.

Edited January 9, 2007 by planetxpimp

[Fish-Finger-er]

am i not right in thinking youve got the way of screwing the b/b in the wrong way round, the right hand side is a left hand thread. you screw the left hand one in clockwise, and screw the right hand one in anti clockwise.

when you look at the cranks, and the way they turn, and the whole tightening up as they turn idea, it initially makes no sense, but in fact, think a little deeper than that, and it does work as the crank spins one way, the bearings rotate, and push the other way on the outside. meaning as you pedal the right hand arm clockwise, the force on the shell is actually anti clockwise. thus tightening the left hand thread on the right hand side.

[TomR]

Yeah you're right, Tarty just PM'd me and i'm about to edit. I wrote this thing ages after i did it and got them the wrong way round.