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Problems with rear detrailleur
#1
Hi,

I have replaced the gear cable on my bike and have tuned it up so the gears are changing correctly, however it won't go into the lowest gear because the upper cog on the derailleur is touching the cog for the lowest gear. I understand from the various articles I've looked at that most derailleurs have a tension adjustment screw but the Shimano gears on my bike appear not to have one. I've stuck a couple of photos below to further illustrate the problem. Any suggestions as to how I might get around this would be most appreciated.

[attachment=1121]
[attachment=1122]
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#2
One thing you need to do is clean that drive train its dirty. It may be there but its so dirty you may not see it.
My dad always told me a Sledge a matic can fix any thing.
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#3
Can you take a photo from the side and back, the normal way up (not top or bottom)?
(There is usually a "B" tension screw to set the dérailleur angle but maybe not in this case.)

Did the gears work perfectly before?

Did you adjust anything else?
Has the chain been removed / altered lately?
If you didn't, and the gears worked before, then I can only think the adjustment is out of line.
Ride hard or ride home alone!
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#4
Something else I would like to add is the wire coming from the last anchor bolt should be moved away from the derailler arm (RED ARROW) and trimmed up (BLUE LINE). If you noticed in the YELLOW CIRCLE the peg has been bent out of shape. Not sure if this will have any effect on performance but might in the shifting. Surely is correct you need to clean up the drive train (Chain, Rear Derailler, Front Derailler, and in between gears) too as this has weird effect on shifting and performance. Hope you do not mind me using your picture to show ya.
One other thing I forgot to mention is to check your chain for wear like Alex's Video tut .... http://bikeride.com/chain-wear/ .
Good maintenance to your Bike, can make it like the wheels are, true and smooth!
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#5
Shimano 7 speed mega range, not a good system and didn't stay in production for long, try searching Shimano's site for info.
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#6
matr,

could you give me a picture of where the red arrow is pointing? Reason is I may think I know another problem making it not shift correctly.
Good maintenance to your Bike, can make it like the wheels are, true and smooth!
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#7
I have a similar budget Shimano mech on one of my bikes. There isn't a B tension adjuster on it and I have the exact same problem. I can only assume that the the largest rear sprocket is too large for the mech to actually cope with.
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