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Tuning the Derailer


lloydkayak
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I was tuning a bikes derailer yesterday with the help of Parktool website :)

 

I set everything (H and L) properly but when I started setting the barrel adjuster accurately I end up getting the gears just shifting up when changing but they won't shift back down easily at all (cable is clean as far as I can tell)

 

I think the chain is worn and the cassette is possibly done. On the high cog pedalling slowly the chain is lifted at a point (missing teeth) then falls back into place??

 

Can I try to just replace the chain or must the cassette be replaced as well?

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This is purely my two cents worth, but are you sure your cable is not to "tight". Loosen the cable a little bit.

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If the cassette is worn, replacing the chain only will cause the new chain to wear to "fit" the shot cassette in double quick time.

 

You can change the chain only if you do it before the cassette is worn.

 

In this case, change the two together.

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I thought the cable might be too tight but if I loosen it to the point that it just changes down in doesn't change back up??

 

What should I be paying for a new chain and 9 cog cassette? LX component bike... don't want to get "rooked"

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If you order from CRC it should cost you considerably less than if you go to your LBS. My last chain and cassette (Sram chain and Shimano HG50 cassette) cost me almost R800! For an additional R200 I could replace chain, cassette and crankset (FSA alpha drive, as original on my GT) with CRC and have the order delivered! My chain and cassette have done around 1800km (I checked last night) and my crankset over 3000km. I think a chain and cassette was around R500 odd with delivery.

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If you remove the chain and rear wheel, does the derailleur shift properly?

 

To me it should shift down regardless of whether the chain and cassette are worn. It may not stay in that gear but it will shift

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With Flow on this one !! Normally you got a sticky cable (not in your case) or a shifter that is not that smoth anymore . My Dual control shifters got very sticky after many years of service and I had same problem .

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Lucky I asked here before ordering... I will remove the cable and see if maybe it is a bit dirty/ catchy... if that isn't the case it can be the shifters then??

 

I will take a look again this evening

 

So with a worn chain and/or cassette the chain will still shift up AND down at the right setting? albeit not too well

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If you do a complete gear overhaul like that you need to start from scratch.

 

1. Release the cable from the derailleur

2. Set H and L screws

3. Set barrel adjusters between full out and full in

4. Attach cable to derailleur using a 3rd hand tool

5. Adjust barrel adjust on derailleur

6. Fine tune inline/frame barrel adjusters

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The white brigade will be here soon to tell you just how a worn groupset will affect your gear shifts . Luckly my bikes are very special , I only service the shock every 5 years , have never serviced my brakes and use a groupset until the chain slips on the chain ring . I can't remember how old the LX GS on my one bike is but it is very old and has done 4 S2C , one Desert Dash , 3 towers and about 10 Babaas races and countless outrides . The point is even though is is missing a tooth from the big blade and is getting close to that point where it will slip if power is applied it still changes perfectly .

 

I also believe that if you are going to change something on your drive train then you replace everything , unless you break sonmething prematurely .

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Its a LX derailler and quite old but we really haven't abused the bikes at all... very chilled riding and the rider weighs like 50kg not like my >100kg.

 

Yesterday a I loosened the cable, set the limit screws and setup the barrel adjusters. reattached the cable (using my dextrous two hands... no third hand tool important??) and started tuning the shifting (until it would just change up to the next cog crisply)

 

Around 3rd or 4th cog I set it to literally crawl up to the next cog and when I try change down it won't go (I have to do 2 or 3 full turns on the barrel adjuster to get it to change down)

 

Is the cable setting tool necessary? I can't see it playing a role with this problem

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When you shift down, is there a click in the shifter? Maybe the shifter was in the wrong gear.

 

If the shifter works 100% and the jockey goes all the way up and down, then it must be the cable AND housing.

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It does change up and back down through gears 8 down to say 5 but no chance on the lower gears. From gears 1 it takes three shifts to move the chain and then it obviously jumps quite irratically

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