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I have a RD-4700-GS SHIMANO TIAGRA (Rear Derailleur,Medium Cage,10-speed) and a CS-HG50-10 (SHIMANO DEORE, 10-Speed, 11-36T MTB Cassette Sprocket). However, the RD-4700-GS is compatible with a Low sprocket_Max. of 34T (Front double) 32T (Front triple) as on the shimano website. What issues can I expect if the sprocket teeth ratios are different? And how perhaps can I resolve this incompatibility?

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Most likely it'll work assuming you don't exceed the derailleur capacity. Shimano specs components by using perfect shifting as the rule. If you exceed the specifications, usually you'll first have slightly less than perfect (but still good enough) shifting before it ceases to work.

By selecting suitably sized chainrings, you can avoid the cassette gearing causing derailleur capacity problems, but chainrings are so expensive that I'd say if you exceed the capacity it's probably easiest to use the 11-34T cassette for which it is intended. However, in today's market you may not find a cassette of the proper gearing and if you do it's likely to go out of stock tomorrow if you don't buy it already today, and if you buy it, the price will be 50% higher than previously.

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  • Thanks for your response. Can you give me a bit more details on why a 11-36T cassette won't work on a max 11-34T compatible rear derailleur? I'm trying to understand what issues will I face in shifting etc. How will I know if I exceeded my derailleur capacity?
    – csheth
    Aug 22 at 10:28
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    You have to adjust the B-tension screw to move the derailleur a bit further from the cassette if using 11-36T cassette on 11-34T derailleur. An inoptimal B-tension adjustment means the shifts might be bit sluggish. I'd say the 34T vs 36T mismatch is so small it's probably not a big issue.
    – juhist
    Aug 22 at 11:28
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    The capacity is calculated as follows: big ring - little ring + big sprocket - little sprocket. Example: 34T/50T and 11-36T is 16T + 25T = 41T. If your derailleur has less than 41T capacity, this setup will not work.
    – juhist
    Aug 22 at 11:29
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    “Can you give me a bit more details on why a 11-36T cassette won't work on a max 11-34T compatible rear derailleur?” The upper derailleur jockey wheel might hit the big sprocket, even with the B screw at the maximum. There are “workarounds” like the Wolf Tooth RoadLink™ which simply moves the derailleur further away from the sprockets.
    – Michael
    Aug 23 at 5:45

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