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 |
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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Originally Posted by DMF
(Post 10162422)
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.
My most important question is what will work on my 7 speed which in anycase is at a 11-23 now |
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 |
Originally Posted by Not the Slowest
(Post 10162485)
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.
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? |
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. |
Originally Posted by DMF
(Post 10162566)
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? |
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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Originally Posted by DMF
(Post 10163117)
Jockey wheels are easily replaced and inexpensive. I'm not sure what parts the Exage xxxx requires, but someone here probably does...
Sometimes I have found great RD deals online that it paid to it versus new wheels. |
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. |
Originally Posted by davidad
(Post 10163882)
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 all |
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