# 1x11 Chain Length? ( 32T Oval to 51T )



## bobcat534 (Jul 22, 2021)

I recently converted my bike to 1x11 and added a full KMC Chain (118 links)

440mm Chain stay length
32T Oval Chainring
51T Largest Rear cog

I checked out few calculators that say I need 112-114 links










I struggled to find the right information online so I though I'd ask you guys

This is how the derailleur looks in highest and lowest gear


























It's not rubbing anywhere at all it is just dropping the chain when backpedaling from largest two cogs

I want to make sure I have the right length of chain and see if that helps

Any help would be appreciated


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## J.B. Weld (Aug 13, 2012)

Assuming your b-screw is set right I'd say you're ok.


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## bobcat534 (Jul 22, 2021)

Thanks for the reply, yep b screw is set up properly

What I wanted to see if having the optimal chain length makes the issue with chain dropping from the last two cogs less present

(btw I have no more space on the frame to move the front chainring for a better chainline)


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## Reaperactual (Apr 20, 2020)

bobcat534 said:


> Thanks for the reply, yep b screw is set up properly
> 
> What I wanted to see if having the optimal chain length makes the issue with chain dropping from the last two cogs less present
> 
> (btw I have no more space on the frame to move the front chainring for a better chainline)


I'd remove one link based on the currently derailleur position on the big and small cog. Doubt it will make any difference regarding big cog derailment though.

I'm running a non Boost chainline on a Boost frame which helps, still get the chain dropping off the big cog after around three back crank rotations. Not an issue to worry about unless your chain drops down instantly? I could back pedal all day without any issues on the second biggest cog.

Chain length calculators are okay and seem pretty accurate but why not try the manual sizing method, see if it matches? I'd also try playing around with your b-gap adjustment some more, maybe it will help enough so it's not gonna be an issue you can't live with.


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## bobcat534 (Jul 22, 2021)

Reaperactual said:


> I'd remove one link based on the currently derailleur position on the big and small cog. Doubt it will make any difference regarding big cog derailment though.
> 
> I'm running a non Boost chainline on a Boost frame which helps, still get the chain dropping off the big cog after around three back crank rotations. Not an issue to worry about unless your chain drops down instantly? I could back pedal all day without any issues on the second biggest cog.
> 
> Chain length calculators are okay and seem pretty accurate but why not try the manual sizing method, see if it matches? I'd also try playing around with your b-gap adjustment some more, maybe it will help enough so it's not gonna be an issue you can't live with.


I was thinking to remove 1 or 2 and that would match perfectly with the calculator

Is the manual method wrapping the chain around the largest cog and the chainring without the detailer and a adding 2 links on that measurement?


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## J.B. Weld (Aug 13, 2012)

bobcat534 said:


> I was thinking to remove 1 or 2 and that would match perfectly with the calculator
> 
> Is the manual method wrapping the chain around the largest cog and the chainring without the detailer and a adding 2 links on that measurement?



Since you installed a complete 118 link chain you would have to remove 4 links to get it down to 114. The calculation you did is wrong, if you remove 4 links the chain will be too short for sure. You might be able to remove 2 links but it looks like it would be real tight in the big cog to me. As mentioned if it were me I'd leave it alone. 

I can't remember for sure what shimano 11 speed wants for their chain length but I think for hardtails it's 2-4 extra links when wrapped around the big cog (bypassing the derailleur) Be aware that you can only remove links in multiples of 2 so impossible to remove just 1 link.


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## huckleberry hound (Feb 27, 2015)

bobcat534 said:


> I was thinking to remove 1 or 2 and that would match perfectly with the calculator
> 
> Is the manual method wrapping the chain around the largest cog and the chainring without the detailer and a adding 2 links on that measurement?


No, you need to consult the Manual for the derailleur. It is add 4-5 links depending on how the chain wrap turns out. There are separate methods for hardtails and full suspension bikes.
This is the only method that I would trust!

https://si.shimano.com/api/publish/storage/pdf/en/dm/MARD001/DM-MARD001-04-ENG.pdf


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## Reaperactual (Apr 20, 2020)

bobcat534 said:


> I was thinking to remove 1 or 2 and that would match perfectly with the calculator
> 
> Is the manual method wrapping the chain around the largest cog and the chainring without the detailer and a adding 2 links on that measurement?


When I said one link I meant remove another inner and outer, (counting back two pins to avoid confusion) obviously you need the inner link on each end in order to fit the master link back on.

I've followed the Park Tool's 'How To Size Your Chain' method on YouTube a few times on full sus and hardtails, worked out fine.

With one full link less (or two pin count) it'll bring your derailleur cage angle down a little, add a bit more chain tension when on the smallest cog. Your derailleur cage will still have a good (hardtail) angle when on the big cog, that's all and not related to your big cog derailment issue.

On the other hand if your reasonably happy with it as it is, don't bother, as mentioned that's okay too.


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## bobcat534 (Jul 22, 2021)

The manual for the derailleur, never crossed my mind! Mine didn't came with one

Sorry, fyi when I said 2 links I was referring to 2 Narrow plus 2 Wide parts of the chain








Exactly this

------------------------------------------------

I'm happy as it is right now,
but I would prefer if there was a bit more space between the chain and derailleur when in the smallest cog









Something like this









There is nothing I can do about chain dropping when backpedaling from the 51T
The added tension could very well fix the dropping from the 45T (second largest cog) 
since it keeps the chain when backpedaling slowly


I'm getting a chain tool tomorrow so I'll try and see how it goes.

Thanks a lot guys!


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## J.B. Weld (Aug 13, 2012)

You said 11 speed in the op so I was going off that. The linked instructions are right of course, always go with manufacturer recommendations.

Check carefully before you cut, easy t remove but impossible to add more back without 2 extra quick links. I know you want more tension in the small cog but look at the big one. Chain is already almost straight and it looks to me if you remove 2 links it will be straight, which means too short.

Anyway, time will tell I guess. Either way it shouldn't affect the backpedaling problem in the least, that's a chain line issue. Really a non issue for all practical purposes.


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## Reaperactual (Apr 20, 2020)

bobcat534 said:


> The manual for the derailleur, never crossed my mind! Mine didn't came with one
> 
> Sorry, fyi when I said 2 links I was referring to 2 Narrow plus 2 Wide parts of the chain
> View attachment 1989249
> ...


I would say removing only one full link will give you the desired and appropriate, chain length, tension and cage angle as shown in your 'something like this' pic.


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