Shimano 39-55?
06-24-23, 05:36 AM
#1
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Shimano 39-55?
I recently hit my outer Shimano 9100 Dura Acre 39-53 chainring. The damage is only cosmetical, but I am thinking that I might want to replace it with a 55 tooth chainring. Will this combination work? Shimano recommends either 39-53 or 41-55. What about 39-55?
06-24-23, 07:14 AM
#2
Keefusb
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You should be OK with the 55 tooth chainring. It's possible that you may need to reposition and/or adjust the FD, and you may need to lengthen the chain. Depends how you are currently set up.
06-24-23, 03:18 PM
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Depends on how you define OK. That exceeds the recommended tooth jump for the front derailleur. How well it will work will only become clear once you do it. And then there is the question of why the OP needs a 55t ring. That's what world class sprinters use with a lead-out train. Of the other 99.99% of riders, it's much more effective to learn how to spin a higher cadence.
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06-24-23, 03:26 PM
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typical Shimano Cage Code.. SS is Short, GS is mid(some road ders. call this "long"), SGS is Long cage.
Diameter change is less onceyou get to bigger tooth counts, but you want to watch for "Tail drag" or chain rubbing on the front der too....
Last edited by maddog34; 06-24-23 at 03:42 PM.
06-24-23, 03:37 PM
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06-25-23, 03:13 PM
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This is the second poster in the last week or two asking about a 55 tooth ring. And I thought the jump from 52 to 53 was significant!
06-25-23, 07:58 PM
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some folks will buy a new Ferarri, and never exceed 100mph...
Last edited by maddog34; 06-25-23 at 08:02 PM.
06-25-23, 08:01 PM
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HA! Love it.
06-25-23, 08:06 PM
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I run a 56-39 and 11-32 but with SRAM eTap Mid RD. Works fine. I've also run it with Ultegra mechanical FD fine. Dura ace?? No idea
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06-25-23, 08:07 PM
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Velomobile riders run 61-33 chain rings. Try shifting that!
06-26-23, 07:44 AM
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Depends on how you define OK. That exceeds the recommended tooth jump for the front derailleur. How well it will work will only become clear once you do it. And then there is the question of why the OP needs a 55t ring. That's what world class sprinters use with a lead-out train. Of the other 99.99% of riders, it's much more effective to learn how to spin a higher cadence.
06-26-23, 08:03 AM
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Because it will cause your drivetrain to work poorly.
06-26-23, 10:26 AM
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"Because it will cause your drivetrain to work poorly."
Only if the mechanic doesn't work well.
50-34 is 16T
55-39 is 16T
Only if the mechanic doesn't work well.
50-34 is 16T
55-39 is 16T
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06-26-23, 12:27 PM
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Actually, at that speed you will be faster if you coast in a tight tuck. Anything over about 55 km/hr and you are faster in a tuck. Pedaling at those speeds is just a waste of energy.
