Bicycle Mechanics - A bike sale and a rear derailluer question......
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02-09-12, 06:04 PM
First, Westside Cycling in Denver, Co is going out of business and will close their doors Feb. 14th or 15th. If your interested its located near Wadsworth and Colfax across from Walmart. They have a few whole bikes on sale and all accessories are half off. They have a lot of stems, front and rear derailleurs(new and used), gloves, some tools, shifters, and other items. I picked up a chain whip and a used rear derailleur today.
Second, the question. The rear derailluer I bought was purchased for parts. The part I Needed was the lower Pulley/cog as mine broke. Now replacing it is straightforward it just has one screw that you pull out. But my question is this, do these pulley/cogs break frequently or its it unusual And to add to this can you purchase these pulley/cogs by themselves?
02-09-12, 06:11 PM
I am pretty sure that the pulleys on rear derailleurs tend to wear fast depending on usage. They start to look like points while wearing down. They all seem to be replaceable because they are a rather high wear item.
02-09-12, 06:57 PM
derailer's pulley can be purchase by themselves .between 10 - 15 a pair .
02-09-12, 07:13 PM
Cool I didn't know these could be bought by themselves. Mine didn't actually wear to a point an entire tooth broke off leaving a gap when it rotated.
02-09-12, 07:32 PM
Replacing the lower pulley is easy as you just remove the bolt and slide out the old, slide in the new and replace and snug the bolt.
Pulleys on off-road used MTBs or on road bikes ridden in gritty and wet conditions and/or with a poorly maintained chain can wear fairly fast. If they are kept clean and dry, a life of 20,000 miles or more is quite possible. I have a 105 9-speed rd with 25,000 miles and the pulleys, while a bit worn, are still in usable condition and the bike still shifts well.
02-09-12, 08:13 PM
I need to check this out!!!!
02-10-12, 12:52 PM
I get pulley sets with just regular bushings for mid-grade Shimano RDs for about $4 - $5 a pair. (At least that was last year). The $10+ set of pulleys or for just the upper pulley is for a special ceramic-bush centeron unit or other fancy name pulley. But if you just want to repair/replace a mid-grade derailleur to get it back to shifting well, a non-ceramic steel-bushing centeron G pulley works fine. I fixed a vintage 600EX RD6207 with just a $3 centeron G pulley and it shifts great with 7-spd brifters. That RD came off originally, a late 1980's Bridgestone 700 with over 6000 miles on it, then went on a street commuter for another 5000 miles until the ridges on the lower pulley were almost gone. And it still shifted then, but the cracked ceramic bushing in the upper pulley were making a funny rapid "click-buzz" noise. I do clean my chain regularly and I think it makes a difference in longevity. But otherwise, I don't replace pulleys that often. If you do replace them, however, think about using some loctite on the axle bolt threads when you retighten the pulley. The RD pulley undergoes lots of vibrations, and the 3mm allen holes are often soft and will strip if over-tightened. A little loctite prevents sudden loss of pulley out in the middle of nowhere with parts strewn down the street - hopefully without a street gutter in the pathway for a critical part to drop into.
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