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Two different cassettes - What length chain

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I'm setting up the gravel/commuter bike with two different cassettes, an 11-32 on the commuter wheels and an 11-34 on the gravel wheels. I appreciate that's not a huge difference but which one should I use to set up chain lenth?

I assume I should use the 11-34


 
Posted : 04/02/2024 6:01 pm
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You might be better with 2 chains and a quick link to match wear more than the length issue.


 
Posted : 04/02/2024 6:06 pm
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If you’re swapping irregularly, two chains.  If not, size on the 34 and adjust b tension for the 32 to take up the slack.


 
Posted : 04/02/2024 6:23 pm
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Size chain for the 34. There’s no need to adjust b tension when swapping those two, they’ve both got the same size small cog, if the mech can take a 11-34 the mech will take up the slack when running the 11-32.

Valid point on chains. Personally I’d run a single chain and replace it before it stretches and causes cassette wear.


 
Posted : 04/02/2024 6:36 pm
thols2 and thols2 reacted
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Thanks everyone, I'll set it up for the 34 and see how it goes, easier to take an extra link or two out later than add one in.

In the subject of two chains, again I'll see how I go. Neither of the cassettes are new so hopefully no problems there as they did get new chains on different bikes not long ago. Moving the groupset over to this one and trying to keep costs down as there has already been loads of stuff to spend on I didn't plan for!


 
Posted : 04/02/2024 7:24 pm
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Would there not be any difference anyway? Set it on small/small and the rear mech capacity takes up the slack?


 
Posted : 04/02/2024 7:50 pm
 csb
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Is it a single gear at the front? If not just stick it in big/big on the 34 cassette to work out the longest chain you’ll need.


 
Posted : 05/02/2024 8:47 am
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I run an 11-34 and 11-36 on different wheel-sets for the same bike. Chain is set up for the 11-36, works fine for the 11-34. I'd size for the larger cassette and see how it goes. It's not a huge difference and you may well find it's okay without any adjustments between wheels.


 
Posted : 05/02/2024 10:15 am
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To answer a couple of questions it's a double on the front, essentially moving the 11speed 105 hydraulic set of my road bike onto this to replace the 10 speed groupset that's there.

I set it up last night for the 34 but in my tired state used the MTB guide rather than the road guide and left a couple of extra links in on "big-big" - need to rectify that before I go any further. Spent most of the evening sorting out cabling so this was a "one last thing before bed" moment when clearly I should have stopped a bit earlier.

I'll set it up for the 34 and see how it goes. Thanks everyone


 
Posted : 05/02/2024 10:55 am
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The difference in chain length is half the difference in the number of teeth on the cog. So 34-32/2 = 1. 1 tooth equals half a link of chain. You'll probably have to wind the b-screw in a bit, maybe half a tooth of chain length so we now have 1 tooth plus half a tooth = 1 1/2 a tooth or 3/4 of a full chain link.
All that to say it'll be the same chain length for both and a small adjustment of the b-screw. Set on the 34


 
Posted : 05/02/2024 1:39 pm