Bicycles/Maintenance and Repair/Pedals/Removing pedals
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A pedal can be removed using a pedal wrench or, sometimes, an allen wrench if there is a hexagonal hole in the inside end of the pedal axle. A normal open end spanner/wrench will work on some pedals; an adjustable spanner/wrench spanner will typically not work, because the head is too wide to fit between the pedal and the crank. A good shop-quality pedal wrench will also be longer than these, for the required leverage. This leverage is also the limiting factor for the use of allen wrenches in this application.
If a normal spanner is all that you have (be it adjustable or not) then you may find that pedal removal is possible, especially if you are removing platform style pedals—these generally have larger lands for the spanner. Just take care not to scratch or gouge the crank arm (see photo at right). Position an adjustable wrench so that, when turned, the adjustable jaw is on the "inside" of the turn.
Usually, you should position the wrench as close to overlapping the crankarm as possible. (So that it is in front of the arm, not extending its line.) Before attempting to remove the right side pedal, make sure the chain is on the largest gear. (That way, if you slip, you'll have a more difficult time impaling yourself on the sharp chainring teeth.)
(Usually the left and right pedals are marked with an "L" or "R" on the end to make identification easy.)
There are two important factors involved in removing bicycle pedals:
- The left pedal (for left foot) has a left-hand thread i.e. it unscrews in the opposite direction to most threads (to unscrew it, you have to turn it clockwise). Left and right side pedals have opposite threads. The right hand, drive side, pedal is right hand (normal) thread; the left hand, non-drive side, pedal is left hand (reverse) thread. The easiest way to remember this is to have the spanner/wrench above pedal and push towards the back of the bicycle; this works on either side. This is not arbitrary--the natural motion of the pedal (which is counter-clockwise) will unscrew the left pedal if it is not left-handed.
- Pedals, especially when they have not been removed in a long time, can be very tight. It is important to apply antiseize compound or grease to the threads before reassembly, to facilitate the next disassembly. Doubly so if the parts will be in a corrosive environment. (Salted roads, near saltwater, etc.) Any general purpose grease is acceptable. Ungreased pedals are very likely to become seized later and make for troublesome removal.
Note that there are basically two sizes of pedal axle threads in common, current-day use: 1/2 inch diameter (SAE thread) for the one piece cranks typically found on cheaper bikes, and 9/16 inch diameter (also SAE) for the two and three piece cranks found on mid-priced and high-priced bikes.
