Rear mech slipping, question for NICK

jez_clarke

Yo Nick,

Was hoping to pick your brain...

OK, so i have fixed a new rear mech to my bike.
My rear mech i have upgraded to a XTR, cassette is also new and xtr as is the chain and chain set...

I'm finding that when in 20 - 23rd gear i get slippage - when changing gears (they shift down) it's very annoying and doesn't give me much confidence when i apply more pressure to accellerate hard, as it's nearly always slightly slipping down a gear.

I thought i lined it all up ok when i stuck the mech on... maybe you can make some suggestions.. i've not fiddled with the small alignment screws since setting the mech up..

If i turn the pedals and gears on the bike stand, it seems ok.. just when i apply more leg power does it slip...

i have a race at gorrick in a couple of weeks, so would like to get it sorted...! cheers buddy

nicklouse

total number of gears?

everything the same speed?

so big ring at the front and which at the back? big rear is 1.

jez_clarke

9 on rear, 3 on front....

Gear is on large front cog, and is slipping on the 4 largest rear gears..

the bottom gears on rear, don't slip..

what do you mean the same speed....?

nicklouse

no miss matched parts form an 8spd or other set up.

so if i get this right when pedalling the bike wants to change to a higher gear (smaller cog)

bent mech hanger?

jayson

Sticky cables??

nicklouse

Jayson it is posible if the mech is a "normal" mech spring pulling to the outside.

it really needs looking at.
instead of net diagnosis.

jez_clarke

hey....

no mis-matched parts.. all 9 speed...

it changes to a LOWER gear (larger cog), not a smaller cog...

the mech doesn't look bent.

jez_clarke

p.s.

the cables are new too

nicklouse

rapid rise then?

get it to a shop.

jez_clarke

yes mate..

it's rapid rise..

supersonic

If I have read this right, you arre using the largest front chainring, but using the the largest rear cogs too? You soul;d only be using the smallest cogs, ie the 11,13,15, and 17. There is no need to use the 23 and larger on the large chainring, it puts the chain at an angle, wears parts quick and can cause the slipping you describe. the 44/23 gear can be easily repplciated on the 32 chainring with a straighter chain.

jez_clarke

supersonic,

thats a good description.. however, i am experencing slippage on the top 3 largest rear cogs, and not sure the top one as you mentioned in your mail...

not sure if the anwer is still the same..?

Splasher

Sounds like classic "not quite indexed" to me.

nicklouse

Right if i have got this correct.

you are using ratios you should not as it can cause excessive wear and early failure.

and the chain is moving UP the cassette towards the wheel.

incorrect indexing, low cable tension. get them set up correctly. and ues your gears correctly.