how to increase derailleur capacity
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how to increase derailleur capacity
My bike's rear derailleur is Shimano Ultegra R8000, short cage, with 30T max cog. I would like to install an 11-34 cassette for better climbing. How can I increase the derailleur capacity? Can I simply install a medium or long cage, with a longer chain? Or, is there more to it than that?
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I've never done it but I think you can swap plates. Part #'s are:
Y3E998080 Outer plate and fixing bolt
Y3E916000 Inner plate
Good luck finding them, your shop will most likely have to order them from Shimano.
Y3E998080 Outer plate and fixing bolt
Y3E916000 Inner plate
Good luck finding them, your shop will most likely have to order them from Shimano.
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My bike's rear derailleur is Shimano Ultegra R8000, short cage, with 30T max cog. I would like to install an 11-34 cassette for better climbing. How can I increase the derailleur capacity? Can I simply install a medium or long cage, with a longer chain? Or, is there more to it than that?
A less expensive alternative that might work, is the Wolf Tooth RoadLink. I used one to increase the capacity of an old XTR derailer so that I could use a 36 tooth low. I could probably put in a 40 but I’m already at a silly low gear. It’s only $21. It might or might not work but it’s a bit cheaper than the other route.
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Yes, installing a longer cage derailer is an option. A medium cage derailer will handle a 34 tooth cog. About $100 for the derailer and extra for the chain.
A less expensive alternative that might work, is the Wolf Tooth RoadLink. I used one to increase the capacity of an old XTR derailer so that I could use a 36 tooth low. I could probably put in a 40 but I’m already at a silly low gear. It’s only $21. It might or might not work but it’s a bit cheaper than the other route.
A less expensive alternative that might work, is the Wolf Tooth RoadLink. I used one to increase the capacity of an old XTR derailer so that I could use a 36 tooth low. I could probably put in a 40 but I’m already at a silly low gear. It’s only $21. It might or might not work but it’s a bit cheaper than the other route.
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My bike's rear derailleur is Shimano Ultegra R8000, short cage, with 30T max cog. I would like to install an 11-34 cassette for better climbing. How can I increase the derailleur capacity? Can I simply install a medium or long cage, with a longer chain? Or, is there more to it than that?
By swapping only the short cage for a medium cage, you are only accounting for the first difference, so it may or may not work with a 11-34, the nominally largest cassette that a complete GS derailleur would accommodate.
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One thing to remember is that all those capacities listed by Shimano aren’t hard and fast numbers. That derailer in the picture is supposed to have a capacity of only 43. I’m running a 48/36/20 crank with an 11-36 cassette. The capacity of that is 53. I recently reduced the crank to a 44/36/20 with the same cassette. That capacity is 49…still above the supposed maximum. Yes, the chain can get a bit slack if I’m trying to run in the highest 3 cogs on the back with the 20 in the front, but I would never run that combination anyway. The whole system works very, very well.
By the way, I’m also way outside the specs of how the front derailer is supposed to work as well. It’s supposed to have a 20 tooth capacity. The 48/20 crank has a difference of 28 teeth and the 44/20 has a difference of 24 teeth. According to Shimano, that shouldn’t work. I can tell you that it works flawlessly as 1200 miles in Wisconsin and Michigan, can attest. And that’s not the first time I’ve used that gearing…not by a very long shot.
Finally, as a fellow researcher was fond of saying, “you can always talk yourself out of an experiment”. Try it. If it doesn’t work, you are out $20. If it works, you saved $80 to $100.
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Picking the Scablands. Washington and Oregon, 2005. Pie and spiders on the Columbia River!
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Plan Epsilon Around Lake Michigan in the era of Covid
Old School…When It Wasn’t Ancient bikepacking
Gold Fever Three days of dirt in Colorado
Pokin' around the Poconos A cold ride around Lake Erie
Dinosaurs in Colorado A mountain bike guide to the Purgatory Canyon dinosaur trackway
Solo Without Pie. The search for pie in the Midwest.
Picking the Scablands. Washington and Oregon, 2005. Pie and spiders on the Columbia River!
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Yes, installing a longer cage derailer is an option. A medium cage derailer will handle a 34 tooth cog. About $100 for the derailer and extra for the chain.
A less expensive alternative that might work, is the Wolf Tooth RoadLink. I used one to increase the capacity of an old XTR derailer so that I could use a 36 tooth low. I could probably put in a 40 but I’m already at a silly low gear. It’s only $21. It might or might not work but it’s a bit cheaper than the other route.
A less expensive alternative that might work, is the Wolf Tooth RoadLink. I used one to increase the capacity of an old XTR derailer so that I could use a 36 tooth low. I could probably put in a 40 but I’m already at a silly low gear. It’s only $21. It might or might not work but it’s a bit cheaper than the other route.
Last edited by Litespud; 08-02-21 at 11:49 AM.
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From what I have read and seen online there are two differences between a Shimano short cage (SS) derailleur and medium cage (GS) derailleur: (1) cage length (obvious); and (2) parallelogram shape difference (less obvious), such that the derailleur travels a different path from the first to the eleventh positions. Difference #1 is mainly to take up the additional chain length necessitated by a larger range cassette, whereas difference #2 is mainly to accommodate the greater difference in diameter between the smallest and the largest cogs in a larger range cassette.
By swapping only the short cage for a medium cage, you are only accounting for the first difference, so it may or may not work with a 11-34, the nominally largest cassette that a complete GS derailleur would accommodate.
By swapping only the short cage for a medium cage, you are only accounting for the first difference, so it may or may not work with a 11-34, the nominally largest cassette that a complete GS derailleur would accommodate.
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11-36
I went one more.
50/34 and 11-36 using FD-R8050-GS derailleur
I even tried to go 46/30, but the rings I purchased placed the chainline outside the adjustment range of the Di2 FD.
SRAM makes the PG1170 in 11-36 (way over Shimano's spec'ed capacity BTW)
If you do choose to go over the capacity number, be sure to get the chain length correct.
I used Park Tools Large/Large +2 method. It's a great youtube video.
Barry
50/34 and 11-36 using FD-R8050-GS derailleur
I even tried to go 46/30, but the rings I purchased placed the chainline outside the adjustment range of the Di2 FD.
SRAM makes the PG1170 in 11-36 (way over Shimano's spec'ed capacity BTW)
If you do choose to go over the capacity number, be sure to get the chain length correct.
I used Park Tools Large/Large +2 method. It's a great youtube video.
Barry