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Old 05-13-09, 07:37 AM   #1
pikestar
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Where to start with gear problem.

Having trouble with the gears on the bike, I have seven cogs on the rear wheel but can not select the two outer most ones. I gave the cables a tighten but once I get to the fifth cog and pull the lever there is no click and doesn't seem to be any more gears to go.

Never done any sort of bike maintenance before so no idea where to start.

Is it likely to be a problem with the gear shift lever or the rear dérailleur, or something else.

Any ideas appreciated.
Oh and the bike uses Shimano Altus A20
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Old 05-13-09, 07:45 AM   #2
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Tightening the cable is the wrong way to go. The outer (smallest) cog is reached by the spring in the derailleur and the cable has to be slack enough to let it go that far.

Also, all derailleurs have "limit screws" that control how far the derailleur can travel in both directions. The "H" (high) limit screw controls how far outboard the derailleur can move.

Either your cable tension or the limit screws could be causing your problem.

Given your lack of knowledge, attempting to adjust the cable or limit screws is as likely to make the situation worse as better. A visit to a good bike shop or locating a knowledgable friend would be a better way to get this resolved.
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Old 05-13-09, 07:48 AM   #3
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Does it have the rapid fire pods under the brake levers?
these have 2 levers to change the gears up and down
could be that they are gummed up and the little sprung loaded claws arent working.
you could try squirting WD40 onto the holes beside the gear lever.
this may breakdown the old hard grease.

would be better if it was dissasembled and regreased. But its a complex job, with lots of little bits

Last edited by griftereck; 05-13-09 at 07:51 AM. Reason: missed a bit
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Old 05-13-09, 08:17 AM   #4
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Quote:
Originally Posted by HillRider View Post
Given your lack of knowledge, attempting to adjust the cable or limit screws is as likely to make the situation worse as better. A visit to a good bike shop or locating a knowledgable friend would be a better way to get this resolved.
Cheers for your concern but I bought the bike for £15 about $23 so there is no way I am paying a bike shop to sort it. Also my commute is very short, don't really need the gears but don't like to have things not working.

I have looked at guides on adjusting the dérailleur but they seem to want you to start with the chain on the outermost cog, so a little confused on how to start.

griftereck - It does have the two change levers under the brake but since they work fine through the first five cogs I was hoping they were ok. The lever will move freely but there seems to be no resistance once I get to the 5th cog.
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Old 05-13-09, 09:09 AM   #5
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If you can't get the chain to the outermost cog, the first thing you want to do is loosen the cable, all the way. Even better, disconnect it. While you're down there, loosen all the barrel adjusters on that cable (turn clockwise until they stop).

Now, if the chain still won't reach the outermost cog, loosen the outer limit screw ("H") until it does.

After satisfying yourself that the chain does run in the outermost cog, ratchet your rear shifter until it's in its loosest position, the highest, smallest outermost cog. You want all tension out of the cable. Now re-fasten the cable at the derailleur while pulling as much slack as possible by hand. If you use pliers or any other mechanical means to pull slack, you'll probably over-tighten, so just pull with your fingers.

Now you're ready to work on the shifting. First, pull remaining visible slack out of the cable by tightening the barrel adjuster (anti-clockwise). Next, try to shift to the next cog. If it doesn't go in, shift back down and tighten the barrel adjuster about a quarter-turn (anti-clockwise). If for some reason it over-shifts (shifts two cogs), shift back down and loosen a quarter turn. Repeat the process of shifting up, then shifting back, and turning the barrel adjuster in increasingly small increments until you can get the chain running quietly in the second cog.

Keep repeating fine adjustment of the cable through all the cogs, using the barrel adjuster. When you get to the last (innermost) cog, adjust the inner ("L") limit screw so you can easily and consistently get the chain onto that cog without over-shifting.

Viola, you're done. If this isn't working you probably have a broken shifter or bent derailleur hanger.
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Old 05-13-09, 09:12 AM   #6
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With the chain on the center cog, pull on the cable to see if the RD moves toward the wheel or away from the wheel (I know one of my wife's bikes is the reverse of normal). It would be helpfull to know this to help troubleshoot.
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Old 05-13-09, 09:13 AM   #7
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Just last night I conducted my first ever derailler adjustments. Followed park tools recommendations and after some fiddling around, I have my bike shifting better than when it came out from the shop.....though I also gave the drive train a thorough cleaning and lubing!
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Old 05-13-09, 09:19 AM   #8
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These should help you sort it, or tell you it needs more attention than you can provide:

http://bicycletutor.com/adjust-rear-derailleur/

http://www.parktool.com/repair/readhowto.asp?id=64

Chances are you can fix the problem with minimal tools. But if it's a bent derailleur hanger - you will need to visit a shop. But the repair is simple and inexpensive. Once you've done what is explained in the 2 links above, and the problem isn't fixed, look for further information on derailleur-hangers and adjusting them.
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Old 05-13-09, 10:03 AM   #9
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Cheers for all the replies dudes, it looks like I certainly got more than just a start now!
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Old 05-13-09, 09:15 PM   #10
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I'm a newb and got lost trying to follow the directions on parktools. After watching/following the direction on this video, got my rear derailleur to work 100% on all the gears. All the doityourself help should be on video.

http://www.youtube.com/watch?v=xkGBajG4TPc
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Old 05-14-09, 10:00 AM   #11
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I am a noob myself. I think you should get yourself a book. The one I have is "Zinn and the Art of Road Bike Maintenance." The problem you are describing is likely simple and one you can fix yourself.
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