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Discussion Starter · #1 ·
I have a new Ibis Ripmo V2 with 12 speed XT 28 x 10-51. When mashing under load in the 28x10 combo the chain skips and clunks, like it’s trying to shift up to the 12t and then falling back onto the 10t. Has anyone encountered this? It doesn’t do it in 28x12 or any lower gear, only 28x10 and only when mashing. Cable tension, b-screw, hi low stops are all where they should be.




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Discussion Starter · #4 ·
Okay. Thanks for the input. So, last night I watched some installation videos and read over the dealer manual on derailleur installation. Then I went through everything from scratch and noticed:

1. The chain is too short. Using the Shimano wrap method, I only count 3 links where there should be at least 5.

2. The b-screws was not correct. I had it set up eyeballed to the cassette as I am accustomed to doing on 11 speed and earlier. I turned it to tighten the gap so it matched the line on the cage. It was off by approx 3-4 mm too much gap.

3. I cleaned and lubed the chain.

Results:

I took it for a spin this morning and the skipping is gone! I did some heavy mashing with no skipping problem at all. Nothing but smooth shifting that I’ve come to expect from Shimano.

The problem must have been the b-screw. I’m surprised that this 3-4 mm tolerance made such a big difference, as I’ve found Shimano to be very forgiving, but then again I can see why it matters.

I’m a little concerned about the short chain, but there does seem to still be just enough capacity in the 28x51 combo even with sag. Would you guys replace it just to be sure, or not worry about it?


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Okay. Thanks for the input. So, last night I watched some installation videos and read over the dealer manual on derailleur installation. Then I went through everything from scratch and noticed:

1. The chain is too short. Using the Shimano wrap method, I only count 3 links where there should be at least 5.

2. The b-screws was not correct. I had it set up eyeballed to the cassette as I am accustomed to doing on 11 speed and earlier. I turned it to tighten the gap so it matched the line on the cage. It was off by approx 3-4 mm too much gap.

3. I cleaned and lubed the chain.

Results:

I took it for a spin this morning and the skipping is gone! I did some heavy mashing with no skipping problem at all. Nothing but smooth shifting that I've come to expect from Shimano.

The problem must have been the b-screw. I'm surprised that this 3-4 mm tolerance made such a big difference, as I've found Shimano to be very forgiving, but then again I can see why it matters.

I'm a little concerned about the short chain, but there does seem to still be just enough capacity in the 28x51 combo even with sag. Would you guys replace it just to be sure, or not worry about it?
If it shifts as desired plus won't bind when bottomed in low gear, personally I'd forget about it.
=sParty
 

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Discussion Starter · #6 ·
If it shifts as desired plus won't bind when bottomed in low gear, personally I'd forget about it.
=sParty
I think that's right. When I'm in the 28x51 all I'm doing is slugging it out going uphill very slowly. I can't imagine I'd ever hit any kind of feature in that gear. And I think there's just enough capacity so that I could without issue.

That said, I went ahead and ordered a new chain that will be here Monday. It's going to drive me crazy knowing it's out of spec so I'll just go ahead and replace it.

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