More On Bottom Brackets

To change your bottom bracket you will need more specialized bike tools as well as a Crescent type wrench.bb_cupcone_rmlv Let’s start by removing the bottom bracket of an old cup-and-cone style; and then replace with a ‘cartridge’ type self-contained BB. Shoot the threads of the left, non-drive side with penetrating oil and let sit.

Here I’m using a hooked wrench (Park Tool HCW-5 Lock Ring Spanner-$15-20USD) to turn the outer ring counter (anti) clockwise. Remove the ring by hand when loosened. Use a large adjustable wrench to remove the spindle, again normal ‘lefty-loosie’ threads. The rusty ball bearings in cages will usually fall right out with the spindle (axle).

The right hand, drive side fitting has reversed threads but can often be removed with a large adjustable wrench such as here. So turn it clockwise to remove it after oil spray. Swipe the BB shell threads with a brass brush, wipe away all rust and dirt and grease lightly [Edit: 12-2014-Per Bob’s Cycle, better to use anti-seize compound if available]. bb_cupcone_rmlv_crescLightly grease the new cartridge style BB and slide it in from the right being careful when starting not to cross-thread. And remember the reversed threads! Screw in counter-clockwise using Park Tool BBT-22 (Shimano Sealed Cartridge Bottom Bracket Tool-around $20USD).

bb_fxdsideIf using a torque wrench use 30 foot pounds, or 40 Newton Meters (Nm) for a Shimano BB. If the BB shell’s threads are shot your LBS can often save it with a tap job (chasing). Grease the threads of the left side keeper ring and thread in clockwise. These are often fragile alloy or plastic so be gentle.

If the cartridge or keeper ring won’t thread in you likely are using a 68mm and need a 73mm or vice is virtue (I avoid French and Italian frames). Or else it’s a non-standard BB shell, intended for a non-standard spindle, that will not fit any sealed cartridge. Give up the frame or rebuild with the cup-and-cone type BB the bike was built with.bb_cart_lftside

So assuming all went well, we have a modern bottom bracket, sealed for life and needing no lubrication, all ready for a new crankset.

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