Chain “bunching” when back pedalling

[TissoT]

I had the same problem so time ago. I took the free hub off cleaned/oil it and still it dragged.

I changed the jokey wheels, the chain was new before the problem started.

In the end I renewed the free hub and the problem was solved.

 

[Ajax Bay]

Besides advice above (clean chain, clean jockey wheels, check freehub), this is more likely to happen if you are in the small chain ring AND one of the smaller sprockets.
When you back pedal you're trying to pull the chain through a well-wrapped (greater resistance) RD cage and then expect the reduced chain tension to offer enough torque (tension x radius of small sprocket) to overmatch the freehub ratchet (springs).
OP - does this happen when you back pedal (briefly) when in the larger sprockets too?

 

[hatler]

All sound physics there ^ ^.

 

[slowmotion]

I had a problem with a freehub sticking a few years ago and decided to try and flush/lubricate it. For the life of me I couldn't actually get into the casing. It seemed to be designed not to be user-serviceable. I looked up the price of a replacement and it was a quite large proportion of the cost of an entire new back wheel. The wheel rims were OK but certainly quite worn. It seems daft but it actually made more sense to junk the wheel and buy a new one.

 

[mickle]

Flush the freehub out with some WD40 ...

WD40 is less than ideal as a replacement for grease within a freehub body. Better to seep some machine oil in there.

 

[Cycleops]

WD40 is less than ideal as a replacement for grease within a freehub body. Better to seep some machine oil in there.

Yeah sorry, meant to add put some light oil in there afterwards.

 

[Big John]

@slowmotion it's possible to service a freehub but I wouldn't bother unless you are seriously anal about bike fettling. Full of microscopic bearings that take on a life of their own. And then you have to piece it all back together. And you need a special tool to do it properly. I'd recommend to anyone with a troublesome freehub......buy another and keep your sanity 👍

 

[gbb]

A simple check...look at your pie plate / spoke protector between the cassette and spokes, make sure its mounted properly and not fallen down and jammed against the cassette, this overcomes the ratchet effect in the free hub.
I know OP states this only happens in the small ring but the check will take seconds and is a cause of chain bunching .