Chain Problem

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Mansfield Marauder
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Chain Problem

Postby Mansfield Marauder » 11 Apr 2008, 2:27pm

I am having problems with my chain I have a 21 speed commuting bike and have problems getting the chain to change up from 3rd to 4th and from 4th to 5th this is a problem on the middle and largest chain rings do not know about the small one as I rarely use it. :(
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natmat
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Postby natmat » 11 Apr 2008, 4:45pm

So, can you change from 1-2-3 and 5-6-7 (and back again), i.e. it's just 3-4-5 that's the problem?

Mansfield Marauder
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Postby Mansfield Marauder » 12 Apr 2008, 9:13am

Yeah it is just the middle cogs when I am changing up going down is no problem at all. Going up from 1-2-3-4-5-6-7 going down 7-6-5-4-3-2-1, 1 being the biggest gog
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Mick F
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Postby Mick F » 12 Apr 2008, 9:28am

It sounds as if your indexing is out a tad.

Any errors may stack up, and could show in mid-cassette.

Try tightening up your cable on one of the adjusters and try again. If that's no good, try loosening.

Other than that, you may have to start from scratch and set up in accordance with the instructions.

You don't say what system you have, but basically you set your shifter to the highest gear (smallest cog). It maybe best to have your bike upside down at this point, or on a stand.

Undo to cable from the rear mech and adjust the limit screw so the jockey wheels are in line with the smallest cog. Refit the cable making sure there is no slack. (very important there is no slack)

Rotate the transmission whilst changing to bottom gear (biggest cog) and make sure the jockey wheels are in line with the biggest cog. Adjust the limit screw to fine tune so the chain doesn't go over the top.

Then get to a mid gear and adjust the cable adjuster screw to make sure the jockey wheels are in line with the cog.

Then go through the whole system, one cog at a time, both up and down.

Then go for a test ride.
Mick F. Cornwall

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julk
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Postby julk » 12 Apr 2008, 12:27pm

If adjusting the indexing as suggested gives no improvement, then it may be time to replace the 7 speed block and chain.

It is possible that you have worn the middle cogs a lot more than the outer ones - do you mostly cycle in the middle gears?

I know I used to wear the middle 3 rear sprockets out when I was commuting.

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meic
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Postby meic » 12 Apr 2008, 3:49pm

Mine has started to be awkward just about going into third from second.
First I cleaned the wires as the obvious first answer then I replaced the cables. The set up had been fine for the first 1500 miles and by my standards is still new. The problem only exists for going into 3rd, unless I adjust the cable tension to make that work, then all the others are wrong.
The next thing to do is to remove the rear deraileur for a total clean and lube, however these new LX's dont come apart at all.
Yma o Hyd

gilesjuk
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Postby gilesjuk » 12 Apr 2008, 5:07pm

A worn chain will create problems too.

Mansfield Marauder
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Postby Mansfield Marauder » 14 Apr 2008, 2:11pm

Thanks for all that I think I will start with Stripping down and cleaning as it is probably over due I do keep it well oiled but not very clean. If the problem is still evident then I will try adjusting everything as I have never been really happy with the gearing set up have fiddled with it until I have got as good as I can but have recently had to remove the chain guard which I believe was not helping things gear change wise. I would not think the chain was worn as it has only done about 800 miles. 8)
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meic
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Postby meic » 14 Apr 2008, 9:49pm

Give special attention to the small bit of outer cable near the deraileur, replace it if you have some spare. The most likely cause of your problem is a bit of dirt or rust in it causing the inner cable to stick.
Unfortunately it wasnt the cause of my problem.
Yma o Hyd