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Old 02-18-06, 05:36 PM   #1
Mr Leon Horsnel
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chain slippage on deore xt hub

When I ride my mtn bike the chain slips when it is on the biggest front cog and either the biggest or second biggest back cog. When the chain is on the second biggest front cog and the two largest back cogs it does not slip as much.
I am new to these things and have bought the bike second hand but it would be interesting to know what this is a symptom of, ie is my back hub or front hub going etc
thanks
leon
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Old 02-18-06, 05:57 PM   #2
sch
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Could be chain wear, check chain length by using a 1/16th marked ruler and centering one end on an easily identified part of the chain and seeing where the same part lies in relation to the 12" marking, If it is 1/8" or more further beyond the 12" mark, the chain is worn. That would suggest maybe the cassette cogs (rear) are as well, or maybe not. The front rings wear more slowly. As a general rule a chain will last 2k to 6kmi, cassette 4k to 12mi and chainrings 12k ++mi. Some people don't do as well and the lower the number of cogs on the rear, the longer the chain lasts. Big chainring and big cassette cog combos sometimes don't work as well and one approach is to not use the big-big combos in the future but when you get close shift to the middle chainring (in front). Similarly the little rear cog and the little front chainring can be problematic. Both ends: big-big and little-little tend to push the limits of chain and derailler wrapup and result in less satisfactory function even if everything is optimized, which may not be the case. www.parktool.com has a repair section with a lot of info on setting up deraillers and shifters, worth perusing.
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Old 02-18-06, 06:34 PM   #3
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If by chain slip you mean pedaling without moving, then you have a freehub problem. The pawls inside the freehub can wear and slip, but it would not matter really what gear combo you are in.
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Old 02-18-06, 07:19 PM   #4
Mr Leon Horsnel
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thanks for that, I went and measured the chain and noticed that some of the little movable rings in the chain links were missing. about 7 also one link seems slightly bent could this cause the problem? the chain seems slightly stretched, although i did not have a good quality ruler
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leon
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Old 02-18-06, 07:25 PM   #5
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Quote:
Originally Posted by Mr Leon Horsnel
thanks for that, I went and measured the chain and noticed that some of the little movable rings in the chain links were missing. about 7 also one link seems slightly bent could this cause the problem? the chain seems slightly stretched, although i did not have a good quality ruler
If you have 7 of those little rollers missing you definitely need a new chain.
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Old 02-18-06, 07:44 PM   #6
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Might be a good time for a new cassette, too; chains and cassettes are happiest when renewed together.
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Old 02-18-06, 08:03 PM   #7
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You should also try to avoid those combinations. By that I mean, instead of going biggest front cog-biggest rear cog, which causes quite an extreme angle that the chain has to assume, go to medium front cog-medium-small rear cog. Basically try not to torture the chain into moving as much laterally as possible.
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Old 02-18-06, 08:19 PM   #8
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What Don said... cross chaining bad. When you're in the big ring in the front try to keep it to the smaller half of the gears in the back, when you're in the little ring in the front keep it in the big half in the back, and when you're in the middle chainring have a field day. Cross chaining every now and then isn't so bad, but keeping it to a minimum will greatly extend the life of your drivetrain. If the chain is that bad (twisted and missing rollers) it's probably time for a new chain, cassette, and chainrings. They all wear out together. Replacing the chain before it gets too bad helps and ends up being cheaper in the long run.
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Old 02-18-06, 09:03 PM   #9
Mr Leon Horsnel
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many thanks
I figured it was not good news, but i am a bit broke at the moment and was hopeing not to spend to much money but...
leon
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