# rear derailleur slipping / how to index gears



## biker99 (Dec 16, 2008)

Hi,

Need a second bike (living in 2 places temporarily), so trying to get my 15 year old mtb back on the road - a great bike in its day (proflex) but a bit dated now and hasn't really been loved as it should in the past!

Was having issues with ghost shift/ gears slipping and started researching, coming across thing like chain stretch (def) and cog wear.

So, I replaced the freewheel (occasionally wouldn't engage), rear cassette, chain and middle/granny rings (ordered a 44t instead of a 42t for the big ring and had already shortened the chain - front derailleur couldn't handle it and ultimately decided the original wasn't it such bad shape.

Went out for a ride - expecting some dreamy pedalling and spent the whole time slipping and sounding like my chain was going to snap or some of my new cassette teeth were.

The only thing I could think of was that the derailleur is regularly trying to shift, ie just lifting the chain out of alignment with the selected rear cog, but not enough to actually shift. (am open to other diagnosis!)

So - how do I adjust it? I have grip shift gears with a barrel adjuster on the bars and an 'indexed' barrel adjuster at the rear. One click per gear (unlike the front where it takes about 6 clicks from granny to middle so no need to index). It only plays up 'under pressure' so cranking it on the stand doesn't help. 

Is there a trick to eyeballing the alignment on the stand - or am I barking up the wrong tree entirely?


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## SteveUK (Apr 16, 2006)

> ...and ultimately decided the original [chain] wasn't it such bad shape.


For your description of only skipping under pressure, I would say that the above statement demonstrates the cause of your problem. Indexing is about getting the correct cable tension to have the chain held in the correct position over the gears; skipping off the gears in the direction of travel indicates worn components. If the old gears (cassette or freewheel?) were worn with the old chain they would work with that but not be able to accept a new one. I suspect that if you fit your new chain, obviously avoiding the gears which will over-stretch the derailleur, you'll find that the skipping ceases.

Rather than rewrite the indexing instructions, here's a link to some I made earlier.


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## biker99 (Dec 16, 2008)

Hi,

Sorry, bit of ambiguity in my phrasing - it wasn't the original chain I kept it was the original 42T ring (as the new 44t one physically wouldn't fit my setup). The teeth looked in reasonable shape (unlike the wave pattern of teeth on the middle) and the skipping happened on all the front rings (new and old alike).

Many thanks for the link - will work through it and see if that cures the prob!:thumbsup:


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## teelow (Sep 28, 2007)

I had a similar ghost-shifting problem while pedaling hard. It turned out that my derailleur mounting bolt (the one that holds the derailleur to the frame) had backed out and allowed the derailleur to wiggle a little bit. I tightened the bolt and the problem went away. Be sure to check that if you haven't already.


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## biker99 (Dec 16, 2008)

I think you are pretty close to being spot-on!

Sorted the deraillleur as per Steve's guide (thanks:thumbsup: ) and noticed loads of play in the back wheel. looks like I left far too much of a gap in the cones after I replaced the bearings:eekster: 

Much much better on the next ride Still a few probs half way round, but the routing for the cable is open and under the bb, so will prob have a look at cleaning that out too!

Thanks for the suggestions guys!


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## manabiker (Jul 18, 2010)

Check your Hanger isn't bent, then watch this vid, it's the best I've found, it sure helped me, Tony explains it simply.. good luck..


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