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Old 02-15-08, 11:09 AM   #1
Hammertoe
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Will a 50/38/26 or 24 Crank Shift Correctly???

I guess the title should say "Will the chainrings shift correctly", not the "Cranks"...



I have an Ultegra 9 speed triple (130/74 BCD) and will be changing out the chainrings for the type of riding I do...

Mostly up hill...

Right now one of my bikes has a 48/36/26 Deore (104/64 BCD) which shifts proper but is getting old and tired...

When descending I do spin out with the 48 x 12 combination...

I was wondering if I can go up to a 50 in the front and still have the proper derailer range with a 26 or 24 small ring...
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Old 02-15-08, 11:14 AM   #2
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How picky are you?

I'm thinking it'll work but your front shifting might be degraded a bit because you're pushing the recommend range. If it was my personal bike I'd definitely give it a try. Worst case, you'll hate it and have to swap it back.
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Old 02-15-08, 11:19 AM   #3
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Thanks...

Not picky, I just am trying to save some money...

I was going to get the TA chainrings and did not want to spend the money on a 50 and a 48 if the 50 did not work...

But I like your thinking...
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Old 02-15-08, 11:20 AM   #4
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According to Shimano, a Deore FD is made for a 48t max chainring and 22t total difference between biggest and smallest rings. Your intended setup would exceed that so you may have problems with the bottom of the chain rubbing the cage or difficulty shifting.

You also need to check your rear derailleur to make sure it can handle the increased wrap required with the larger biggest ring.

Personally, I would simply coast once I get up to the point of spinning out. At high downhill speeds, you are wasting a lot of energy fighting wind resistance for just a little extra speed.
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Old 02-15-08, 11:35 AM   #5
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I use an Ultegra 9 speed FD and an XT RD...

Do you know the max chainring and total difference allowed for the Ultegra 9 speed FD (6503)...

Thanks...
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Old 02-15-08, 11:35 AM   #6
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It should shift OK, and you can always tweak the FD a bit, but there are other avenues to get there.

Why do this, when you can slap a Sram road cassette on with a 11t cog? Or remove one of your existing cogs, and add a Shimano 11t plus the 11t lock-ring?
48-11 will get you plenty of top speed.
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Old 02-15-08, 07:06 PM   #7
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What kind of shifters do you have? With bar-end or downtube shifters, anything will work on the front end. With STI, trimming (or lack thereof) will be an issue, so you won't be able to use all cogs with the middle or large chainrings.

Other suggestions:
– Could you swap your crankset (and maybe bottom bracket) between your old bike and new one?
– FSA makes a 48-38 ramped and pinned pair. If you have STI, it might help. NO idea of the price.


By the way, I have two bikes with 105 front derailleurs and bar-end shifters. One has an XT crankset with 44-34-22 and the other had an FSA road crankset with 48-38-24, and now has a quad with 48-38-28-18. The derailleur has no problem handling those extremes.
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