Chain tension too loose. How to fix?

[Paul Healy]

Hi

On my old mountain bike when I stop pedalling the chain goes very slack and
if I pedal backwards it comes completely off.
How do I go about fixing it? (not used to fixing bikes at all, so keep it
simple).

 

[Pete Biggs]

Paul Healy wrote:
> Hi
>
> On my old mountain bike when I stop pedalling the chain goes very
> slack and if I pedal backwards it comes completely off.
> How do I go about fixing it? (not used to fixing bikes at all, so
> keep it simple).

Might be a derailleur problem (weak/broken spring?) but I think most
likely is a faulty freewheel (or faulty freehub freewheel mechanism) on
the rear wheel. This probably would need replacing as most are not
economical to repair. Bike shop job.

Flushing freewheel with solvent or oil usually doesn't help when the
problem is this way round (pawls sticking down instead of up).

~PB