Replacing Chainring
09-03-05, 12:20 AM
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Replacing Chainring
My old 10 speed has a Sugino double crank and the large chainring is 53t, question, can a remove the 53t chainring and replace it with a 50t chainring or do I need to replace the entire crank? I ask this because I have seen replacement chainrings for sale and thought it may be possible to just swap out one size for another??
09-03-05, 08:00 AM
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Check the bolt circle diameter (BCD) of your current crank and be sure the new chainring has the same one. The two common sizes are 110 mm and 130 mm. Your old Suguino is likely to be 110 but measure to be certain.
The easiest way to tell is to measure between the centers of two adjacent chainring bolts. A 110 mm BCD will have a bolt-to-bolt distance of 64.7 mm and a 130 mm BCD will have a bolt-to-bolt distance of 76.4 mm.
And Sydney makes a good point. If the chainrings are riveted on, you're SOL.
The easiest way to tell is to measure between the centers of two adjacent chainring bolts. A 110 mm BCD will have a bolt-to-bolt distance of 64.7 mm and a 130 mm BCD will have a bolt-to-bolt distance of 76.4 mm.
And Sydney makes a good point. If the chainrings are riveted on, you're SOL.
09-03-05, 08:33 AM
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^^^...Well, I have Suginos that are even 144. But a good measurement is worth 1000 guesses. The # for 5 hole 135 rings is 79.5 and for `144, it's 84.6mm c-c.
09-03-05, 08:12 PM
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You will probably also need to lower your front derailleur to match up with the smaller outer ring If you have a brazed-on derailleur that can't be lowered, there might be some sub-optimal shifting.
