John, If this is a one-piece crank (both crank arms and the axle are all one piece) then you would need to tighten the bearing. This has an adjusting nut and a large locknut. There are special tools for this, but you can get by with a pipe wrench for the lock nut. However, if this is a three-piece crank, then you probably have a loose crank arm (or two). The axle (which you cannot see) has square ends (about 1/2 inch) that are tapered toward the end (just a little smaller). The cranks have correspondingly tapered square holes. You simply have to tighten the nut or bold on the end of the axle to draw the tapered parts together tightly. There is probably a little cap covering the nut or bolt. The cap usually unscrews with a straight screwdriver. Common size for the nut or bolt is 14 mm. You will need a thin-wall socket for this, or a special crank-arm wrench. Park Tools is a great source for the special tool and lots of how-to info and videos. Good luck.
Answers & Comments
John,
If this is a one-piece crank (both crank arms and the axle are all one piece) then you would need to tighten the bearing. This has an adjusting nut and a large locknut. There are special tools for this, but you can get by with a pipe wrench for the lock nut.
However, if this is a three-piece crank, then you probably have a loose crank arm (or two). The axle (which you cannot see) has square ends (about 1/2 inch) that are tapered toward the end (just a little smaller). The cranks have correspondingly tapered square holes. You simply have to tighten the nut or bold on the end of the axle to draw the tapered parts together tightly. There is probably a little cap covering the nut or bolt. The cap usually unscrews with a straight screwdriver. Common size for the nut or bolt is 14 mm. You will need a thin-wall socket for this, or a special crank-arm wrench. Park Tools is a great source for the special tool and lots of how-to info and videos. Good luck.