Singlespeed chain tension...

[jam1e]

How tight should it be? I'm of the impression that the tighter you can get it the better...

Just got the brakes to set up/adjust and then my first build is done! Looking good too, even if I do say so myself...

 

[icantthinkofausername]

Should have 1/2-1" of movement vertically when you push it with your finger. Come on then, post up some pics!

 

[thecannibal]

I've always felt that guidelines on chain tension based on measured amount of play are a little wrong-headed. I believe Sheldon Brown was the main proponent of this approach. Also, 1" is really quite a lot; too much, I would say.

I would simply suggest the correct tension is the tightest possible, while still leaving the drivetrain free-running at the chain's tightest point. If the chain is very tightloosetightloose as you rotate the cranks, Sheldon does have great advice for this.

Sheldon Brown will be sorely missed.

 

[one-eyed_jim]

I've always felt that guidelines on chain tension based on measured amount of play are a little wrong-headed. I believe Sheldon Brown was the main proponent of this approach. Also, 1" is really quite a lot; too much, I would say.

I would simply suggest the correct tension is the tightest possible, while still leaving the drivetrain free-running at the chain's tightest point.

In fact, Sheldon says simply:

[chain tension] ... should be tight as it can be without binding

http://sheldonbrown.com/singlespeed.html#tension

 

[jam1e]

So basically tight but not too tight! Cheers all.

 

[nicklouse]

I would also like to add to this conversation the issues brought about by different rear cog/drive setups.

IF a geared body with a converter is used. then the tension should be less than if a dedicated SS driver is used.

is a freebody and SSkit then for max body life the chain should not put any undue tension on the body bearings.

 

[one-eyed_jim]

IF a geared body with a converter is used. then the tension should be less than if a dedicated SS driver is used.

Can you explain briefly what the difference is?

If I set up a "dedicated SS driver" as described above ("tight as it can be without binding") what's the advantage of using any more slack with a converted geared freehub? That won't decrease the loads on the freehub body, and only increases the risk of dropping the chain.

 

[one-eyed_jim]

Morning thoughts. We tend to use the word "tension" (noun) sloppily to mean the reverse of "slack". When we talking about tensioning the chain, we really mean removing slack from it. The ideal we're aiming for is zero slack and zero* tension when the chain is at its tightest.

 

[dookie]

IF a geared body with a converter is used. then the tension should be less than if a dedicated SS driver is used.

i think he means freehub/SS cog vs. thread-on freewheel. either way, too much tension will prematurely wear everything! chain, chainring, cog/freewheel, rear bearings, BB bearings.

be sure to use SS specific cog/freewheel/rings (ie: not ramped/pinned to encourage derailment during shifting) and keep a good chainline, and you can run a fairly loose chain without worry.

 

[Andy R]

IF a geared body with a converter is used. then the tension should be less than if a dedicated SS driver is used.

be sure to use SS specific cog/freewheel/rings (ie: not ramped/pinned to encourage derailment during shifting) and keep a good chainline, and you can run a fairly loose chain without worry.

On nice smooth terrain maybe you can, but on rocky, rooty trails I'm not so confident, as the chain can slop about sideways, as well as vertically, and this is what leads to it derailing.
Yes, the proper sprockets and rings and a good chainline are all important, but so is a correctly adjusted chain.

I set the tension so that if I quickly spin the cranks backwards I can get a couple of revolutions of the cranks - any less and it probably is too tight.
I try never to have any actual "slack" in the chain, and certainly not even half an inch - I'm pretty fussy about this.