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Old 05-27-11, 02:07 PM   #1
bluefoxicy
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Moved my front derailleur to fix it. Found broken gears..

I took the lower limit screw OUT.

It still rubbed, LOUDLY, in first and second on my small chain ring.

Okay, fine, I'll move the WHOLE assembly. I undid ... whatever the clamp is, I guess you call it a "boss" or something, I don't know ... twisted it just a few degrees, just barely get about 1-2mm clearance ... and locked it back down. No vertical movement.

Put that screw back in, screwed it in until I nudged the derailleur cage back just barely cleared off the chain. It spins with no noise now.

I had to adjust my cable tension to set the center chain ring up right. It's set up right now. Shifts perfectly. Every gear from absolute low to absolute high slides through that cage with no noise.

Fixed the upper limit, too. It just barely shifts (if I bring my upper limit in any tighter, I can't shift to high), and it's just barely cleared off the chain in the highest gear on the biggest chain ring.

Perfect.

I actually had to move the friggin' derailleur to get it to adjust properly.

By the way! This bike has about 320 miles on it. The center chain ring has very much variable teeth! Some have chips off the edge, some are half as long as others ... the lower and upper rings are worn some, too. I've managed to somehow tear this little low-end probably $10 crankset up! Oddly enough, the gears on the back look pretty much fine. Someone earlier supposed that my bike might have a busted tooth, which I thought was ridiculous ... nope, it's taking serious wear to the chain rings.

I want forged steel chain rings. I actually see how they come off now.

Sigh ... guess I should do the rear derailleur. next. It's only auto-shifted once, though.
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Old 05-27-11, 02:31 PM   #2
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I'd mention that many chainrings have some teeth that are specifically designed (i.e., shorter, appearing to be worn/damaged) to aid in shifting, but you must already know that.
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Old 05-27-11, 02:32 PM   #3
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Follow this: http://www.parktool.com/blog/repair-...nts-derailleur

Then: http://www.parktool.com/blog/repair-...ur-adjustments

The chainrings may not be damaged. Teeth are shaped differently to aid shifting. Are you sure the teeth look different than originally?
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Old 05-27-11, 02:38 PM   #4
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The chainrings may not be damaged. Teeth are shaped differently to aid shifting. Are you sure the teeth look different than originally?
No, but they look pitted oddly, and they look irregular. It's not like every third tooth is half as short. My rear cogs I did a double-take at, too; but closer examination revealed a regular pattern. I'll take a closer look, though; grocery run time.
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Old 05-27-11, 03:15 PM   #5
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It's not neccesarily a regular pattern in front, but usually based on the the crank arm location. Chainrings last years, not 320 miles.
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Old 05-27-11, 04:23 PM   #6
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Hmm, some of this looks like it might be intentional.



But there's a lot of pitting and chipping here and there.



Eh dunno. In any case the shifting is nicer except...
  • Minimal rattle on the smallest chain wheel in 4th gear; it rubs significantly in 5th.
  • A tiny bit more cable tension needed, as sometimes I have to nudge my shifter to stay on the center chain ring.
  • Can't use the lower gears on the biggest chain ring methinks. The bottom three rub.

I thought only one or two would drag in any chain ring and the center chain ring would have full reach.
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Old 05-27-11, 05:05 PM   #7
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Sometimes the best thing to do is disconnect the cables and set up both derailleurs from scratch. Follow the Park Tool instructions I linked above.
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Old 05-27-11, 06:28 PM   #8
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Sounds like it makes noise when cross-chaining. That's good, because cross chaining is bad. An audible reminder that you're cross-chaining could be seen as beneficial.
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Old 05-27-11, 08:01 PM   #9
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Sometimes the best thing to do is disconnect the cables and set up both derailleurs from scratch. Follow the Park Tool instructions I linked above.
+1
Do all of the steps in sequence leaving nothing out.
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Old 05-28-11, 07:04 PM   #10
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How can a chain get that filthy in only 320 miles?
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Old 05-28-11, 07:08 PM   #11
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How can a chain get that filthy in only 320 miles?
ride it in the rain and slap a whole mess of lube on the chain
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Old 05-28-11, 07:36 PM   #12
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That crank looks pretty much OK. Clean your chain and see how it shifts.
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Old 05-28-11, 07:46 PM   #13
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There's no doubt that there's some rust on that middle chain ring and that it's made from steel.

Two things. With only 320 miles on it to develop those pittings and corrosion you need to review your storage place and conditions. Either that or you live and ride along the ocean... like it's across the road. Your area where you keep the bike is obviously quite damp.

And a hearty and emphatic +1 on cleaning the chain. Is your riding area extremely sandy?
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Old 05-28-11, 07:48 PM   #14
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Your chainrings are fine. You should not be riding in the smallest 3 rear while in the small front nor the largest 3 rear while in the large up front.
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Old 05-29-11, 07:26 AM   #15
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There's no doubt that there's some rust on that middle chain ring and that it's made from steel.

Two things. With only 320 miles on it to develop those pittings and corrosion you need to review your storage place and conditions. Either that or you live and ride along the ocean... like it's across the road. Your area where you keep the bike is obviously quite damp.

And a hearty and emphatic +1 on cleaning the chain. Is your riding area extremely sandy?
I'm storing it in a garage behind my house, it's dry and sheltered. I've ridden the bike in the rain once. Ridden it through mud too; it's pretty covered in mud, I need to clean the entire area around the bottom bracket. Like a third of the frame severely needs a cleaning and maybe a good coat of turtle wax, but I don't want to get that stuff on my gears.

Park tool sells a chain cleaner, guess I need that.
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Old 05-29-11, 08:06 AM   #16
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Originally Posted by bluefoxicy View Post
.
I actually had to move the friggin' derailleur to get it to adjust properly.

The center chain ring has very much variable teeth! Some have chips off the edge, some are half as long as others
Having to move the front derailleur to make it shift properly isn't uncommon at all. If that isn't right you can fiddle all day with limit screws and cable tension and never get it to work.

Variable chainring teeth is normal. They are designed that way to assist shifting. I'll bet that if you look exactly opposite the "deformed" teeth you'll find another set just like them.
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Old 05-29-11, 08:11 AM   #17
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How can a chain get that filthy in only 320 miles?
That's not uncommon at all. Once some people learn the importance of lubricating their chain they redo it, withoug cleaning off the old gunk, every time they ride. While doing tech support on some big charity rides I've worked on some chains that were so gunky I didn't want to touch them with my pliers. What did the rider want? - More chain lube.
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