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Combining two 11-speed Shimano cassettes

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Combining two 11-speed Shimano cassettes

Old 05-09-21, 07:15 PM
  #26  
SoSmellyAir
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Originally Posted by Davidb67 View Post
Iím considering a Frankenstein-cassette - Shimano 11sp r8000 Ultegra, to go with 52/36 sub-compact crankset.
my thoughts are to take a 12-25T cassette, and an 11-32T.
like the idea of single tooth increments from the 12 so 12-13-14-15-16 and was wondering if using a 17 but then going to 20-22-25-28-32 - would the 3-tooth strep between 17-20 be too big? - I note of course that 22-25-28 are also 3 tooth increments, with final 28-32 being 4T difference.

I could use the 18T instead which would be 16-18-20, but I have a feeling that 17T would come in handy for my riding/cadence/road-speed.
itís for a road bike, variety of terrain, some quite lumpy hence the desire to go to 32T.

appreciate any thoughts.
thanks,
david
I have tried combining two Ultegra cassettes (11-28 and 12-25) to make a 12-28 cassette, and it did not work out even though I took care to match the cog markings specified in the Shimano Dealer Manual for the Dura-Ace 12-28 cassette.

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Old 06-05-21, 03:27 PM
  #27  
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So I finally got hold of 2 new CS R8000 Ultegra cassettes - a 12-25, and a 11-32T.
my Di2 6870 rear mech is short cage, so for now I put the cassette onto my wheel, and put the bike up onto the stand, turned the cranks and shifted up and down through gears, but avoiding the final 2 lowest - 30T & 32T so as not to foul anything up.
ive got a 17-20T jump, and although that shift isn’t quite as crisp as the rest when changing to lower gears, it certainly didn’t struggle jumping away until it “caught”, more just a fraction of a second longer to jump on to the larger sprocket, than the others.
definitely looks workable but I don’t know whether this running OK on the bike stand is in anyway similar to what I would find out on the road…..if it’s as I’m seeing, then I’d be happy and prepared to buy the new 8050brear mech - medium cage.

be interested in peoples thoughts
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Old 06-05-21, 05:06 PM
  #28  
CliffordK
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I've run a merged cassette for quite a while. I've been off of it for a year or so recently (time to get it back on the road). For me it is a little crunchy at the shift point, but not too bad.

I'd probably choose a single tooth progression for the split if possible.

So, for the OP's post:
12-13-14-15-16-18-20-22-25-28-32 Merged with 11-12-13-14-16-18-20-22-25-28-32

One has a choice of splitting (12-13-14-15) (16-18-20-22-25-28-32) 1 tooth jump
vs (12-13-14-15-16) (18-20-22-25-28-32) 2 tooth jump

If possible/practical, I'd choose splitting between the 15/16 for a single tooth jump.
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Old 06-05-21, 10:34 PM
  #29  
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I did something similar but with 10 speed. I have multiple bikes so it made sense to combine from multiple cassettes. Otherwise, you might just need one or two single cogs to get the results you want.
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Old 06-05-21, 11:37 PM
  #30  
SoSmellyAir
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Originally Posted by Davidb67 View Post
So I finally got hold of 2 new CS R8000 Ultegra cassettes - a 12-25, and a 11-32T.
my Di2 6870 rear mech is short cage, so for now I put the cassette onto my wheel, and put the bike up onto the stand, turned the cranks and shifted up and down through gears, but avoiding the final 2 lowest - 30T & 32T so as not to foul anything up.
ive got a 17-20T jump, and although that shift isnít quite as crisp as the rest when changing to lower gears, it certainly didnít struggle jumping away until it ďcaughtĒ, more just a fraction of a second longer to jump on to the larger sprocket, than the others.
definitely looks workable but I donít know whether this running OK on the bike stand is in anyway similar to what I would find out on the roadÖ..if itís as Iím seeing, then Iíd be happy and prepared to buy the new 8050brear mech - medium cage.

be interested in peoples thoughts
Perhaps follow the OP's gearing: 12, 13, 14, 15, 16 (from the 12-25 cassette) and 18, 20, 22, 25, 28, 32 (from the 11-32 cassette) to avoid having a three teeth jump in the middle of the combined cassette.

Also, the largest two cogs should be 28T and 32T, so a short cage RD should have no problem shifting the chain onto the 28T (assuming appropriate chain length).
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