Bicycle Mechanics - Changing the middle chainring on Shimano Triples
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05-27-08, 05:32 PM
I am thinking about changing the middle chainring on my Shimano 105 & Ultegra Triple cranksets. I've notice that Shimano's 10speed cranks now come with 52/39/30 chainrings. My current setup is 52/42/30, and I want to change the middle chainring to a 39, will I need to change the front derailleur as well?
Thanks for you help.
05-27-08, 05:40 PM
You'll be Ok with what you have. I picked up a used 105 9-speed group a few years ago. Ditched the granny ring and swapped the 42 for a 39.....It still shifts just fine.
05-27-08, 06:34 PM
I've played mix-and-match with Shimano road triples too. I routinely swap out the 30T granny for a 26T and have done just what you are asking about by substituting a 39 for the 42 middle ring for a friend. Worked fine with the original fd.
You'll have better luck if you use a middle ring with ramps and pins designed to work in a triple.
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