# Newbie question: vertical dropouts & chain tensioner



## decipher (Aug 17, 2007)

Hello,

This might sound silly, but I don't get why it is necessary to use a chain tensioner to achieve a usable chain tension with an internal gear hub (or single-speed) setup and vertical dropouts.

Obviously, lack of a chain tensioner may mean use of an eccentric bottom bracket instead, but is it possible to use neither and achieve the appropriate chain tension assuming that no slack is needed in the chain to allow for different chainring and sprocket combinations?

Thanks


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## Drew Diller (Jan 4, 2010)

Assuming I've set reasonable tension on a single speed bike with sliding dropouts, I can use a chain tool to successfully separate the chain.

I cannot, at all, ever, get the chain back together.

I feel ya though, I'd like to do without the tensioner bits (eccentric BB, or sliding dropouts, or chain tugs, or a spring tensioner wheel). Maybe build a device that can forcefully bring together some links while keeping them parallel?


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## decipher (Aug 17, 2007)

Drew Diller said:


> Assuming I've set reasonable tension on a single speed bike with sliding dropouts, I can use a chain tool to successfully separate the chain.
> 
> I cannot, at all, ever, get the chain back together.


In words others you are saying that the slack in the chain is required for putting it (back) on?


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## dru (Sep 4, 2006)

It doesn't matter, the chain will slacken as things wear. There is no way around this. On my Alfine the 1st season I've had to readjust the tension probably 2 or 3 times with the EBB. You really, really don't want to run with the chain loose; with vertical drops and no tensioner and the fact you have no derailleur or guide either it will be only a matter of time before the chain comes off. That would suck if you were really hammering. 

Drew


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## Drew Diller (Jan 4, 2010)

decipher said:


> In words others you are saying that the slack in the chain is required for putting it (back) on?


Yes.

I could get the links in the correct position with a large amount of finger strength, but the amount of arm strength required meant my hands got shaky, and I never had a third hand available for using the chain tool. I would seriously be a two person job, if that would even work, as I imagine four hands in that small a space, aside from impractical, I doubt it would even work.

I have tried using a zip tie, as well as taking an old brake cable and twisting it in order to pull things together with more force than my (fairly strong) hands could muster. Never got it to work.


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