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Old 08-15-08, 06:24 PM   #1
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A 48-tooth replacement for a "Shimano FCM341-L w/ Replaceable Rings, 22/32/42t"?

Does a 48 tooth replacement exist for the Shimano FCM341-L w/ Replaceable Rings, 22/32/42t that came with my bicycle? The bicycle's tech page can be found at

I was originally hoping to just replace the top-ring but the LBS said that would result in significant performance differences due to the whole crank-set being "specially designed" or whatnot. So, I'm starting to think replacing the whole crankset would be the best route but is it possible? If so, would a Shimano Ultrega 48 tooth crankset work fine? I'm not sure how compatible my particular bicycle is with other components but I'd like a 48 tooth front for maintaining 30 mph without pedaling as if I were a madman(30 mph on the flat).
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Old 08-17-08, 12:16 PM   #2
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Road cranksets have a different chainline measurement...45mm instead of 50mm? 46t 104mm chainrings are available...I had one on my bike for a while, shifting was a bit weird, but it worked okay.
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Old 08-17-08, 12:24 PM   #3
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Make sure you post over at the mechanics forum, too. Lots of knowledgeable folks there also.
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Old 08-17-08, 11:11 PM   #4
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BikeMan (this isn't the only one) has them. They are used on lots of touring bikes as 'Trekking' rings. You'll probably want to swap the middle ring too. A 48 to 32 is a big jump. You might want to calculate the gear inches for a 42/11, 44/11, 46/11 and 48/11. 48/11 is a pretty tall gear and is larger in diameter than most mountain bikes use.
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