Running a 28 with a 9speed short cage DA?
04-25-09, 07:00 PM
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Running a 28 with a 9speed short cage DA?
Anyone running a 28 in the rear with a short cage DA? I know a 27 will work, but my knees would rather a 28.
04-25-09, 07:16 PM
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depends on your derailer hangar placement compared to the axle drop out.
but most likely yes it'll work.
but most likely yes it'll work.
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Food for thought: if you aren't dead by 2050, you and your entire family will be within a few years from starvation. Now that is a cruel gift to leave for your offspring. ;)
https://sanfrancisco.ibtimes.com/arti...ger-photos.htm
04-25-09, 07:17 PM
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Shimano road RDs can go beyond the maximum cog spec of 27t. Most will handle a 30t cog with perhaps some B-screw adjustment.
The other factor to consider is chain wrap. The spec there is 29t. Calculate wrap using:
(Big ring + big cog) - (small ring + small cog).
If you have a 50/34 compact then a12-27 cassette is already over the wrap spec by a bit. It's well known to work on just about all bikes, although you will need to set the chain length carefully. If you want to go to an 11-28 then you are more likely to run into problems, like not being able to shift into the big ring/big cog combo or the chain rubbing on the smaller cogs when in the small ring. I would not recommend having the chain so short that you can't shift into the big ring/big cog. Even though you shouldn't cross-chain like that, you should be able to shift to it in case you do it by mistake.
The other factor to consider is chain wrap. The spec there is 29t. Calculate wrap using:
(Big ring + big cog) - (small ring + small cog).
If you have a 50/34 compact then a12-27 cassette is already over the wrap spec by a bit. It's well known to work on just about all bikes, although you will need to set the chain length carefully. If you want to go to an 11-28 then you are more likely to run into problems, like not being able to shift into the big ring/big cog combo or the chain rubbing on the smaller cogs when in the small ring. I would not recommend having the chain so short that you can't shift into the big ring/big cog. Even though you shouldn't cross-chain like that, you should be able to shift to it in case you do it by mistake.
04-25-09, 07:24 PM
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you may need to adjust the derailler body out with the "B" screw to clear the larger cog. this is well covered by park tools or sheldon brown.
04-25-09, 09:05 PM
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I am running a 39-53 upfront. The goal is to be able to swap wheels from my 12-25 setup for climbing. I do not want to mess with the RD every time I swap. Will a 27 make things easier?
