MTB chain slipping on front cogs

[Tiggsy]

GF's MTB has a chain slip issue.

When on the largest front cog and the largest rear the chain line is (as you'd expect) way off - thi shas the habbit of pulling the chain onto the middle cog. Good gear selection has got her round this - but out today and the middle cog slips to the smallest when using the largest rear cog. Is that a possible sign of worn chain/crank set cogs?

[Barchettaman]

Could be, could also be that the front mech is out of adjustment.

Are the (front) chainrings worn i.e. pointy? Google 'worn chainring' and compare.

Cassettes and chains are cheap.

[PDP76]

A front mech adjustment might do it. The way you are using the gears though is pretty much not recommended. Using the gears like that ( at extreme angles, rather than lined up) will stretch your chain.
If your teeth look ok, get a new chain and the front mech tuned.

[Tiggsy]

PDP76 said:

A front mech adjustment might do it. The way you are using the gears though is pretty much not recommended. Using the gears like that ( at extreme angles, rather than lined up) will stretch your chain.
If your teeth look ok, get a new chain and the front mech tuned.

I'll stick up a pic of the cogs latter

[WinstonWolf]

The chain is probably worn from being used crossed out, if using the gears "correctly" doesn't solve it I'd replace and get in the habit of swapping across the front mech a bit more

[Tiggsy]

prob now is middle cog up front and large on the back is not that extreme a choice that it should cause the front to slip to smaller cog - looks like new chain

[Gren]

If the chain is so far gone that it's skipping you could find that you need to get new cassette and chainrings as well. They 'mould' to each other so fitting a new chain will now not fit with the worn cassette/rings.

Try the chain first as it's cheaper but I learned this the expensive way and now keep a closer eye on chain stretch.

[PomBstard]

Just had the exact same problem with my bike. Swapped in a new chain and cassette, but needed the rings as well. Quick easy job with the right tools, and not too expensive for parts either from CRC. Crankset with BB was only 10% more than rings alone.

[budgie smuggler]

PomBstard said:

Crankset with BB was only 10% more than rings alone.

Nips my tits that does.

[Tiggsy]

hmmmm.....new crank set, chain, cassette - sounding pricey

[PomBstard]

Tiggsy said:

hmmmm.....new crank set, chain, cassette - sounding pricey

Can't remember the exact amount, but came in at around AU$230 (call it GBP115) for the bits for a 2x10 XT crankset, 10-sp XT cassette and SRAM chain to match. Took me less than an hour to remove the old stuff, clean the bike/hub, and fit the new stuff. Test ride yesterday shows marked improvement

[Tiggsy]

stupid question - I assume i need to replace with the 3/7 configuration she has right now? A 1/11 set up is tempting if only to keep it simple but she'd die on the hills without a granny option!

[Gren]

Tiggsy said:

stupid question - I assume i need to replace with the 3/7 configuration she has right now? A 1/11 set up is tempting if only to keep it simple but she'd die on the hills without a granny option!

If you don't stay with 3x7 you'll need a pair of shifters as well.

Plenty of 2x10 setups on Pinkbike etc (where I got my last lot from) as everyone flocks to 1x10/11 and switches stuff that came on their new bikes

[Tiggsy]

if I go 2/10 - do i need to worry about current set up if buy a whole new config? or will any full config fit?

[gazza285]

If it is seven speed then you might need a new rear wheel as well, the freehub won't be wide enough for anything bigger, assuming it's not a freewheel.

[frisbee]

gazza285 said:

If it is seven speed then you might need a new rear wheel as well, the freehub won't be wide enough for anything bigger, assuming it's not a freewheel.

Dropout width is smaller as well, so an 8 speed or above wheel won't fit.

You may be able to open it up with the big stick of wood method but I don't know if I would like to try that.

[Tiggsy]

ok - so looking at the bike the chain and rear cassette look iffy - front rings look ok but I suppose a shagged chain will drop off anything if bad enough?

so - going to swap the chain and rear cassette and see how I go - do I need to get anything in particular? Its an 11-29 tooth 8 speed on the back so will anything matching that do ? Or close to that? and any chain?

looking at getting these:

http://www.chainreactioncycles.com/shimano-hg71-6-...

http://www.chainreactioncycles.com/shimano-acera-h...

how many links do i need in the chain??

[Craikeybaby]

You size the chain on the bike, there are plenty of guides online to do it, I think I used the Park Tool one when I did mine.