Chain slipping.

[jifdave]

My brother has one of these http://m.evanscycles.com/products/specialized/hardrock-sport-disc-2010-mountain-bike-ec019399

Recently his chain has started to slip. He went to the LBS and they said replace the rear cassette and chain.
I have changed these and he rode it today and it's still slipping.
Is it likely that I need to change the front cogs?
Could it be the rear derailed cogs?

If it is front cogs can someone link me to a cheap new one?

 

[MattHB]

Is it slipping on the front?

 

[slowmotion]

Is it slipping on the front?

Genuine question: how do you tell if it's slipping on the front or the back?

 

[MattHB]

Genuine question: how do you tell if it's slipping on the front or the back?

I have no idea! But I guess you'd have an idea from listening to it

 

[MrJamie]

I think it can also be poorly indexed gears or poor use of gears, putting power down when its halfway between sprockets from incomplete gear change or changing gear while pulling away at a junction out of the saddle can make it slip or if the indexing is off so that either the chain skips between sprockets or is reluctant to change gears. That was my problem recently when i had a bit of chain slip, or at least correcting the indexing appears to have cured it

You could look at the wear on the front chainrings, see if the one he uses most is more worn and spiky than the others and if thats the one the chain slip occurs.

 

[jifdave]

Definately slipping at the front.

 

[jaynana]

i'm not an expert at this but general physics would suggest that it is near impossible for the chain to slip at the front, with so many cogs sharing the load of pushing the chain at any given point.

chain slippage usually happens or starts at the smallest cog at the rear, where the least amout of teeth do the power transfer from the chain to the wheel.

i've had this expereince with a worn out chain once.

 

[PpPete]

i'm not an expert at this but general physics would suggest that it is near impossible for the chain to slip at the front, with so many cogs sharing the load of pushing the chain at any given point.

chain slippage usually happens or starts at the smallest cog at the rear, where the least amout of teeth do the power transfer from the chain to the wheel.

i've had this expereince with a worn out chain once.

Not at all impossible - as I know to my cost.
Had "slipping chain" on our tandem some time back, aha thinks I and expensively replaces freewheel (yes it is that old) and chain....and ...oh bugger, it still slips.
What I had completely failed to notice was that the teeth on the middle chain ring were half their original height - and that this was obscured by the outer chain ring.

 

[andrew_s]

If a chain slips at the front, it rounds off the tips of the worn chainring teeth and slips much easier next time. It can go from first slip to unable to ride up a moderate hill in one ride.