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Old 12-18-09, 10:50 AM   #1
Not the Slowest
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Compatable Upgrade RD Question for my 7 speed Shimano set-up Road bike

Hi all
I have a 7 speed Exage RD that I would like to swap out .

Most likely I will stay with the 7 speed set-up, maybe put on a 8-9 comaptable down the road if it fits.

Questions:
Can I use a 8-9 Shimano RD such as a 105 or ultegra back there with the current 7 set-up?
Could I use a triple 8-9 RD even if I have a double in the front? My reason is that I may want to through a LARGE
cassette in the back one day.

Thanks
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Old 12-18-09, 11:35 AM   #2
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You will need a mountain bike RD with a large (I presume you mean something like a 14-34) cassette. Just about any one will do. 105 and Ultegra are road RDs and won't handle cogs that big.
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Old 12-18-09, 11:50 AM   #3
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You will need a mountain bike RD with a large (I presume you mean something like a 14-34) cassette. Just about any one will do. 105 and Ultegra are road RDs and won't handle cogs that big.
Actually I believe with a long cage RD (triple) you CAN use a 14-34 or similar. The problem is the double rd usually will not go past 28.

My most important question is what will work on my 7 speed which in anycase is at a 11-23 now
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Old 12-18-09, 12:06 PM   #4
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If you are talking about friction shifting then yes, a long cage RD will work for you. If you are talking indexing then chances are good it won't work, or it won't work well, so if you want to keep the indexing I would vote to wait until you can replace everything at once with the group you want. In the case of friction, replace what you want to you hearts content.

I am currently running the following on:
Campagnolo Veloce front triple (30,42,52)
Campagnolo Record Triple FD
Campagnolo Centaur RD mid-cage
Campagnolo friction downtube shifters
Sunrace 7 speed - 13,15,16,18,20,22,24
SRAM PC870 Chain

Last edited by canopus; 12-18-09 at 12:13 PM. Reason: added info
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Old 12-18-09, 12:14 PM   #5
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Quote:
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Actually I believe with a long cage RD (triple) you CAN use a 14-34 or similar. The problem is the double rd usually will not go past 28.
You are wrong (and so is canopus).

Cage length has nothing to do with the size cog a RD will handle. Cog capacity is constrained by the parallelogram geometry; the cage constrains only chain wrap capacity. Shimano road RDs - of any cage length - are spec'd to handle up to 27T, but will generally handle up to 30T.

Any RD will handle 7-speed 11-23. So what's wrong with your Exage?
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Old 12-18-09, 12:44 PM   #6
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If you want to go with a cassette larger than a 30, go with an MTB rear derailer. Road derailers are rated for only 27 or 28 (but they can often be coaxed to run OK on a 30). Earlier this year I put a Shimano Deore RD-M510 MTB "9-speed" rear derailer on my commuting/touring bike and I run 7-speed on that rig. It's been working great and it was only $22.

Some Shimano MTB rear derailers are low-normal (Shimano calls them RapidRise). I've read they are supposed to shift better but I've never tried one. I think the Deore LX RD-M580 is low-normal.

Last edited by Gonzo Bob; 12-18-09 at 12:57 PM.
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Old 12-18-09, 12:51 PM   #7
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Quote:
Originally Posted by DMF View Post
You are wrong (and so is canopus).

Cage length has nothing to do with the size cog a RD will handle. Cog capacity is constrained by the parallelogram geometry; the cage constrains only chain wrap capacity. Shimano road RDs - of any cage length - are spec'd to handle up to 27T, but will generally handle up to 30T.

Any RD will handle 7-speed 11-23. So what's wrong with your Exage?
One Jockey wheel is missing a tooth half of another, but shifts just fine. Its my commuter beater bike and I rather not have to walk home if possible. That said its time for a new chain and cassette. I'm planning on a 12-28 cassette so I figured I would just cover my bases now that the snow is coming and I have time to work on it ...
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Old 12-18-09, 02:06 PM   #8
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Jockey wheels are easily replaced and inexpensive. I'm not sure what parts the Exage xxxx requires, but someone here probably does...
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Old 12-18-09, 02:58 PM   #9
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Jockey wheels are easily replaced and inexpensive. I'm not sure what parts the Exage xxxx requires, but someone here probably does...
I have had the hardest time figuring the size or finding it on theweb.
Sometimes I have found great RD deals online that it paid to it versus new wheels.
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Old 12-18-09, 04:19 PM   #10
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Put a 105 long cage in case you go for a triple. It will handle a 30t cog. Go for an LX if you think you will go as large as a 34t cog.
If you want to replace the jockey wheels go to The Third Hand Loose Screws and get the Ultegra 8sp's and they will work.
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Old 12-20-09, 09:25 AM   #11
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Put a 105 long cage in case you go for a triple. It will handle a 30t cog. Go for an LX if you think you will go as large as a 34t cog.
If you want to replace the jockey wheels go to The Third Hand Loose Screws and get the Ultegra 8sp's and they will work.
Thanks I'll look for a 105 long cage, that will do the job.

Thanks all
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