Schwinn none - Manual (Page 95)

76
CRANK SET
The crank set refers to the bottom bracket axle and bearings, the
crank arms, and chainrings.
Your bike may be fitted with either a one piece crank, where the crank
arms and bottom bracket are a single component, or cotterless cranks,
where the crank arms bolt onto the bottom bracket axle without using
old fashioned type cotterpins. The one piece system is simpler and
requires less maintenance, while the cotterless system requires a little
extra care.
Never ride your bike if the cotterless cranks are loose.
This may be dangerous and will damage the crank
arms beyond repair.
Inspection
The crank set should be checked for correct adjustment and tightness
every month. Cotterless crank axle nuts must be kept tight, and the
bottom bracket bearings must be properly adjusted.
Remove the chain and try to move the cranks from side to side with
your hands. The cranks should not move on the axle, and there
should be only very slight movement in the bottom bracket. Next,
spin the cranks. If they don't spin freely without grinding noise, then
adjustment or lubrication will be needed. Also check that there are no
broken teeth on the chainrings, and wipe off excess dirt and grease
that may have built up on them.
Fixed Cup
Ball Bearing
Lockring
Adjusting
Cup
Axle
Standard Bottom Bracket Assembly (Cotterless)
Cotterless Crank