Bicycle Mechanics - 600 Chainring replacement

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bertsot
06-18-02, 12:42 PM
I currently have a Shimano 600 double crankset with 53/42 chainrings. I want to change the 42 to a 39. Will an Ultegra chainring fit? Or does anyone know where I can buy one for the 600 crank?

Thanks in advance

Albert

ljbike
06-18-02, 01:11 PM
Your LBS should have a chart to measure the hole pattern on the 600. I thin, but am not certain, that it is 130mm. But you also have to match the number of bolt holes 4, 5 or 6. Most Shimano's, are 5, but they do have 4.

So, IF the size and bolt hole pattern is the same as Ultegra, it will fit. In fact, any chainring with the same size and bolt hole pattern will fit. The thing to remember is to keep the Spacing Between the chainrings the same for proper shifting.
Rural Roadie
06-18-02, 06:43 PM
The model number on the back should read FC-6207, at least thats what my nos 600 EX crank says on it, even the FC-6400 series cranks should be 130 bolt circle diameter if its a double.
Hope this helps.
kev:)

John E
06-18-02, 07:34 PM
If your crankset is less than 20 years old, it will have the standard 130mm BCD, and the 39-tooth ring will mount onto the spinder. Your biggest concerns will be shifting in front with the larger jump, and the ability of your rear derailleur to take up the slack in back. If you have only 6 or 7 cogs in back, you may also pick up some redundant ratios. My suggestion: replace the 53 with a 50 when you replace the 42 with a 39.