Join Date: May 2004
Location: Wilmington, DE
Bikes: 1984 Trek 660, 2003 Specialized Hardrock, 2004 LOOK KG386i (RIP), 2005 Iron Horse Warrior Expert, 2009 Pedal Force CX1, 2014 Islabikes CNOC 14 (son's)
Mentioned: 1 Post(s)
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Most cranksets do not include a bottom bracket. A 1991 bike might still be using a cup and cone bottom bracket which means you may be able to get away with some new ball bearings, some grease, and a proper adjustment. As for the crank, it's almost always cheaper to buy a whole new crank than to replace chainrings. However, are you sure your rings are worn out? Chainrings often have strange features on the teeth in order to aid shifting. A LOT of people mistake these features for damage or wear.
If you just want something cheap, go to www.niagaracycle.com
and sort cranksets by price. There are some dirt cheap Shimano options that use non-replaceable steel chainrings riveted to the crank. You may need a different bottom bracket length though so be sure to confirm that spec before ordering anything. Again, Shimano makes some dirt cheap cartridge bottom brackets that will work just fine, if you need one.
If you are looking to upgrade, all of the "better" cranksets these days use outboard bearings, a completely different style of bottom bracket than your current bike. for those cranks, you buy the crankset and a set of cups with bearings. The chainline is fixed so no need to worry about spindle length.