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Old 08-28-11, 10:05 PM   #1
seve1241
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Chain Skipping...

Hello,

I am new to biking. I just bought an used Trek 6500. The only problem is that in certain gears it seems that the chain is skipping. What I think it seems to be is one of the derailleurs is not positioned completely right so in certain gears the chain is hitting the derailleur and it is almost trying to switch gears when it isn't supposed to.

Is this a common problem? Is it difficult to adjust the derailleurs? Any advice would be great.

Thanks
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Old 08-28-11, 10:25 PM   #2
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Do a search on you-tube for adjusting derailleurs and the barrel adjuster -- lots of good instruction videos on how to do it.
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Old 08-29-11, 12:35 AM   #3
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www.parktool.com has repair instructions online. Chain skipping is also a symptom of excessive chain/chainring/rear cog wear. If it only does it for certain chainrings or cogs, that suggests the chainring or cog is worn. You can also directly measure the chain to check if it's "stretched" (acually, worn).
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Old 08-29-11, 05:10 AM   #4
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.75mm or 1.0mm FTW!
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Old 08-29-11, 06:29 PM   #5
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Also, can anyone tell me the year of this bike? Its a yellow frame and purple lettering. Trek 6500 Alpha ZX. Has mostly bontrager and shimano components.
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Old 08-29-11, 06:31 PM   #6
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It is the one with a Manitou front shock
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Old 08-29-11, 07:34 PM   #7
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Try bikepedia
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Old 08-29-11, 07:47 PM   #8
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Specifically, this entry: http://www.bikepedia.com/QuickBike/B...6500&Type=bike
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Old 08-30-11, 09:49 AM   #9
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So I pinned down what gears skip. On the rear cassette it is gear 5, 6, and 7. So now I don't think its the derailleurs... Where should I start? The chain? Rear cassette? Any more ideas?
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Old 08-30-11, 10:47 AM   #10
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Almost certainly, you have a worn cassette. On a cassette worn enough to skip, you almost certainly need a new chain too since your old worn chain will skip in most gears of a new cassette.
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Old 08-30-11, 11:44 AM   #11
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Almost certainly, you have a worn cassette. On a cassette worn enough to skip, you almost certainly need a new chain too since your old worn chain will skip in most gears of a new cassette.
Agreed. The chain skipped on my 1972 last night as I crossed a very busy thoroughfare...not a good feeling. I replaced the chain which was worn and had streched, but the chain skip became worse, such that I could sit on the side of the road and turn the pedals watching the chain dragging over the 20-tooth cog. A new freewheel is on the way.
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Old 08-30-11, 01:28 PM   #12
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The type of skipping that the OP described may be due to a poorly adjusted rear derailleur cable tension, not necessarily a worn cassette or freewheel cog. Or it could be both. Adjusting the derailleur(s) should be tried first.

Last edited by Al1943; 08-30-11 at 01:47 PM.
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Old 08-30-11, 02:06 PM   #13
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The type of skipping that the OP described may be due to a poorly adjusted rear derailleur cable tension, not necessarily a worn cassette or freewheel cog. Or it could be both. Adjusting the derailleur(s) should be tried first.
I Re-read and agree. Try adjustments to fine tune first. If it shifts better but still skips, chain and cassette are next. If you are not comfortable doing this work with the help of the park tools web site or youtube videos, a local shop should be able to help you out.
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Old 08-30-11, 02:16 PM   #14
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Agreed. The chain skipped on my 1972 last night as I crossed a very busy thoroughfare...not a good feeling. I replaced the chain which was worn and had streched, but the chain skip became worse, such that I could sit on the side of the road and turn the pedals watching the chain dragging over the 20-tooth cog. A new freewheel is on the way.
As you found, putting a new chain on a very old cassette or freewheel can cause skipping.

OP, follow the suggestions about derailleur adjustment first.
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Old 08-31-11, 02:44 PM   #15
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Thanks.

If I am to replace the cassette, what tools with I need? Are there any special lockrings or chain tools I will need?
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Old 08-31-11, 03:00 PM   #16
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http://www.parktool.com/blog/repair-...ewheel-removal Add a chain tool because that will be next. If your are buying on the internet, you will save shipping by buying at the same time.
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Old 09-02-11, 09:43 AM   #17
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Well I adjusted the front derailleur - which is the one that I knew was off. The back seems aligned according to the videos on youtube. But it is still skipping. I am looking for a new rear cassette, any suggestions. All my components are Shimano deore, 9 speed, 11-32 teath, chain size is 1/2 x 3/32. I am looking for a decent good priced cassette. I don't want to put a lot of money into it. I also will need a chain. Is it a bad idea looking into an used one? Any advice would be great!
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Old 09-02-11, 09:56 AM   #18
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For the parts you need go to Amazon.com
I get a lot of my parts here.Don't get a used chain get all new parts.Good Luck
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Old 09-03-11, 04:50 AM   #19
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This may be cheaper:
cassette:
http://www.jensonusa.com/store/produ...ssette+10.aspx

chain:
http://www.jensonusa.com/store/produ...+Chain+10.aspx
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Old 09-03-11, 11:58 PM   #20
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New chains are some of the cheapest bike parts, and far too critical (and quick wearing) to consider used. As for tools, you will need a chain tool, a chain whip, and a cassette tool (make sure you get one for shimano cassettes). Also a large-ish adjustable wrench will be useful. I would expect it to run $50ish in parts (depending on how high-quality you get), and $40-$50 in tools (again, depending on how high quality you get).
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Old 09-04-11, 02:34 PM   #21
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I just ordered a Sram PG970 cassette with a Sram PG971 chain. Sram is compatible with shimano correct? I also bought the parktool FR-5 cassette lockring tool. I have a chain tool, and a chain whip. I hope it goes well...
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Old 09-04-11, 08:20 PM   #22
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I just ordered a Sram PG970 cassette with a Sram PG971 chain. Sram is compatible with shimano correct? I also bought the parktool FR-5 cassette lockring tool. I have a chain tool, and a chain whip. I hope it goes well...
correct
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Old 09-04-11, 09:59 PM   #23
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In my case, my skipping was the freehub and not the cassette. If the teeth aren't heavily worn, you may need to service or replace the free hub (assuming all of the above advice about trying the easy stuff first doesn't fix the problem)
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Old 09-07-11, 02:37 PM   #24
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FYI: I replaced the 14-24 freewheel on my 1972 International and it is like riding a new bike...a 180 degree turnaround in shifting!
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Old 09-09-11, 05:32 PM   #25
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Hey I'm running into a new problem why I'm waiting for the parts. My front tube keeps popping. I've on my third already. The last one lasted one day. I'm not even using for mountain biking right now, just commuting. The front tire looks really worn out... Is it commonly the tire or I have been reading that sometimes its bad tape on the rim, or something along those lines. Any advice on where to start would be great!
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