Drivetrain Maintenance

Rusty Chain.jpeg

If you ride your bike on the streets of Chicago (or anywhere else, for that matter), you will at some point experience the dreaded drivetrain wear. The drivetrain of your bicycle consists of the chain, and all the parts that it touches: the front chainrings, rear cassette, and front and rear derailleurs. This whole system is what makes the bike go, and yet it is often the most overlooked aspect of bicycle maintenance.
Under normal riding conditions, the continuous tension on the chain causes it to gradually elongate (how? click here for a detailed explanation). Add moisture, dirt and salt from the road, and you accelerate the destruction.
You can assess the condition of the chain through a scientific process known as empirical observation.
Eyeball the chain. Is it slick and shiny? Then consider yourself lucky. If it's black and goopy, or dry and rusty, things are not good.
Feel the chain between your fingers. If it's very sticky, or brittle and stiff, you've got problems.
Measure the chain. You can do this with the chain on the bike. Place the zero point of an accurate ruler in the center of one of the pivot pins on the chain, and measure out 12 inches. On a new, unworn chain, the 12" mark falls in the center of a pivot pin. If the pin on your chain falls beyond the 12" mark, use the following guidelines:

  • if the distance is less than 1/16", no problem, just clean and oil your chain regularly (see below)

  • if the distance is 1/16", you will need to replace the chain, but probably not the sprockets

  • if the distance is 1/8", you will need to replace the chain and the cassette

If your chain is worn beyond this point, you may even need to replace the front chainrings, or at least the one you usually use. If this is where you are, forget about DIY maintenance, and check with your friendly local bike shop about getting a complete tune-up. Unfortunately, since a badly worn chain causes uneven wear on the cassette and front chainrings, replacing the chain at this pont is not enough. Other worn-out drivetrain components will not work with a new chain, and must to be replaced.
The good news is that you can prevent untimely drivetrain demise by keeping it clean and well-lubricated, and replacing worn parts promptly.
If your drivetrain is very dirty, clean it with hot, soapy water, using household dishwashing detergent, a bucket and a stiff nylon brush. (Please do not take your bike to a car wash, as the hoses use excessive pressure.) Scrub all parts throughly, and repeat, if necessary. Rinse and rag off thoroughly.
Once the chain is clean, apply a good quality bicycle lubricant to each chain link, and to pivot points on both derailleurs, and rag off excess. DO NOT use grease, household oils, WD-40, motor oil, etc. on your bicycle chain. These will attract a lot of dirt, and actually cause the chain to wear faster.

If you’re starting with a new or thoroughly clean chain, modern chain lubricants will save you a lot of time, and make frequent, thorough degreasing (such as described above) completely unnecessary, and even detrimental. With repeated use, these lubricants form a slippery polymer coating on the chain which repels moisture and dirt. Regular reapplication of the lubricant will both clean and lubricate the chain.
Begin by applying a drop of lubricant to each link, and turn the cranks until all links have been oiled. Next, hold the chain through a rag with your left hand while turning the cranks backward several revolutions with your right hand. If your chain looks very dirty, you may have to repeat this whole procedure. Then go ride. That’s all.
NOTE: It’s important not to mix different brands of chain lubricants, since you may end up with unpredictable results. Our preferred lube at Cosmic Bikes is Dumonde Tech bicycle chain lubricant, which we affectionately refer to as “tune-up in a bottle”.