coaster brake and chain tensioner

[dracothered]

I just saw a note on a website that stated you could not use a chain tensioner with a coaster brake wheel.

http://sheldonbrown.com/harris/singlespeed.html#freewheels

Note! Chain tensioners cannot be used with fixed-gear or coaster brake systems!
They don't maintain tension when there is backward force applied to the pedals, and the chain can derail as a result.

Is this true?

 

[GearNut]

Yup.
And nope.

One cannot use a typical tension device like a multi-speed deraileur.
If you can use a motorized bike drive chain type of tensioner and keep the overall chain deflection down to an inch or less, you should be fine. Just remember the side of the chain that has the load on it will go tight and the opposite side loose.

Pedal power = top run tight and bottom run loose.
Braking power = top run loose and bottom run tight.

 

[2door]

As always GearNut is correct. I run a chain tensioner on my pedal side chain on a coaster brake hub. The tensioner is fixed, adjustable but not spring loaded therefore the chain is always the same tension when pedaling or braking. Never had a problem with this setup.
Granted, the tensioner bracket must be rigid enough to prevent any flex or loosening of the chain when braking but if designed right that's not a problem.

Tom

 

[dracothered]

Ok, basically it can't be a spring loaded type and shouldn't give in anyway. No problem then the way I see it.

 

[bairdco]

like they said...

pedaling backwards when braking creates an enormous amount of force, a lot more than you'd expect, and any cheap tensioner would fail.

 

[Mr.B.]

I made a spring loaded one for my bike...

But it’s designed so the end of the tensioners travel slightly exceeds the the taunt chain while the brake is being used.

-Kirk