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Old 02-12-10, 03:13 PM   #1
ClarkinHawaii
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Derail. pulley contacts new larger gear ring??

Hi, Experts--

My everyday beater bike is a 1994 Specialized Hardrock that's pretty much stock.

The original crankset is 28-38-48.

The original cassette is 12-28 (7-speed Shimano HG)

The original rear derailleur (still installed) is Shimano Alivio.

I recently replaced the 12-28 with 12-32 (7-speed) SRAM cassette.

The capacity of the present-day Alivio rear derail is 34 teeth. I'm hoping it was the same back in '94 when this was new.

If upper pulley contacts gear wheel, tighten down on the "B" screw until proper gap.

My problem: I've tightened down all the way on the B screw and there's still contact/vibration/noise when I'm in the small chainring/largest gearring combination.

Interestingly, there is no such contact when I am in the middle or large chainring.

I installed a new chain when I installed the new cassette. I sized the chain according to Sheldonbrown; but the only thing I can think of is that the chain is too loose. When I am in the small cr/largest gr combo, if I pull on the chain (same affect as a shorter chain), the pulley separates from the gear ring. So it's obvious that the derail has the capacity for this 32-tooth gear ring. Could the spring (s) have lost their zing over the years?

I'm stumped.

Last edited by ClarkinHawaii; 02-13-10 at 12:47 AM.
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Old 02-12-10, 03:17 PM   #2
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http://www.parktool.com/repair/readhowto.asp?id=64
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Old 02-12-10, 10:44 PM   #3
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Finished stating my situation in post #1 above--HELP!! (please)

My problem is not solved by the info in the Park Tool link above.

Last edited by ClarkinHawaii; 02-12-10 at 11:34 PM.
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Old 02-12-10, 11:36 PM   #4
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Finished stating my situation in post #1 above--HELP!! (please)
Capacity is not max cog spec. Capacity is the ability of the derailleur to take up slack over a large gear range combo. That has nothing to do with how big a rear cog it handles. Your alivio was most likely spec'ed for about a 27/28 max cog. Throwing a 34t is sure to blow that limit.

So in short, you need a new rear derailleur that handles the 34. For example a deore M571-gs will handle a 34t rear cog (shimano spec), with a capacity of 33t. The sgs version of that derailleur also handles 34 max cog, but with a 45t capacity. You will find many pages that describe what the two terms mean exactly. Do some research.
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Old 02-12-10, 11:36 PM   #5
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Read before posting useless replies.
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Old 02-12-10, 11:39 PM   #6
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Read before posting useless replies.
Perhaps you should have read it before he edited it.
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Old 02-12-10, 11:42 PM   #7
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If you have an extra new longer chain around, I'll try that first before resorting to a new rear derailleur. Rear derailleur specs are generally quite conservative (e.g., Campagnolo's short cage derailleurs are rated to 26T max, but one can use their 13-29T without issue) so you may still be clear.
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Old 02-12-10, 11:42 PM   #8
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Perhaps you should have read it before he edited it.
And my post is 100% relevant to his "edited post". Thanks for the useless contribution.
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Old 02-12-10, 11:45 PM   #9
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If you have an extra new longer chain around, I'll try that first before resorting to a new rear derailleur. Rear derailleur specs are generally quite conservative (e.g., Campagnolo's short cage derailleurs are rated to 26T max, but one can use their 13-29T without issue) so you may still be clear.
His current setup requires a 40t capacity derailleur. Not to mention the max cog size is most likely not even close to a 32.
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Old 02-13-10, 12:55 AM   #10
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Thanks, Guys--I neglected to research this, not suspecting that an mtb couldn't handle a 32-tooth cog.

Also, please excuse the confusion over that original post--my fault, for sure.
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Old 02-13-10, 01:01 AM   #11
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Thanks, Guys--I neglected to research this, not suspecting that an mtb couldn't handle a 32-tooth cog.

Also, please excuse the confusion over that original post--my fault, for sure.
MTB has nothing to do with the derailleur. You could put on a short cage 'road' derailleur that would take 27t as a official listed spec - max cog. Or one that will take 34t.

If you are in error and believe that you only need a slight b-tension increase to gain the correct clearance, then you can reverse the screw in it's slot - the b-tension screw head will provide more clearance in the reverse slot. Note this is a hack solution but it will work.
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Old 02-13-10, 02:30 AM   #12
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Your chain is too long, that is why it is rubbing in the Small ring/larger cog, but not in the mid ring/large cog. But will the derailleur be long enough to handle the large/large combo?
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Old 02-13-10, 11:22 AM   #13
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And my post is 100% relevant to his "edited post". Thanks for the useless contribution.
Your response to repilezs was what I was referring to, as the OP hadn't completed his post when he posted it (OP had to go run to the bathroom or something urgent apparently). Reptilezs answer was valid at the time, making yours the useless contribution in that regard. Have a nice day.
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Old 02-13-10, 12:09 PM   #14
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Your response to repilezs was what I was referring to, as the OP hadn't completed his post when he posted it (OP had to go run to the bathroom or something urgent apparently). Reptilezs answer was valid at the time, making yours the useless contribution in that regard. Have a nice day.
My apologies in that case.

My answer was only written in response to the edited post #1. I would've said the same thing post reptilezs said without the bolded edited.
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Old 02-13-10, 12:22 PM   #15
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This states that the Alivio 410 will take a 34tooth cog, unless I read it wrong.
http://techdocs.shimano.com/media/te...9830612587.pdf
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Old 02-13-10, 01:13 PM   #16
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This states that the Alivio 410 will take a 34tooth cog, unless I read it wrong.
http://techdocs.shimano.com/media/te...9830612587.pdf
OK, these are the specs I had looked at before my initial post; and that is why I was stumped.

The Alivio RD-M410 should handle my situation with no problems since my 32-tooth biggest cog is less than the 34 it will handle; and the capacity (43) is more than my situation (40).

My Alivio unfortunately is not handling it. Note that my Alivio is a RD-M010. Either they have changed the capacity of the Alivio in the intervening 16 years OR
I've got the wrong screw (too short) in my B adjustment hole, or some other malfunction of the derailleur (which is why I asked if springs lose their zing or whatever)

In any case, i don't want to buy a new rear derailleur for a bike that has to be kept outdoors in the weather. You'd think there would be lots of used low-end long-reach derails around, but I don't know where to find them.

So at this time my options appear to be:
1. Put back my 12-28 that was working just fine until I decided to improve things. OR
2. Keep the new 12-32 cassette on but readjust the chain length for the biggest cog and the MIDDLE ring instead of the biggest cog and the biggest ring. This should work OK as long as I remember not to shift into the biggest rear cogs when I am in the big chainring.

Since I already know what it's like with my original configuration, I think I'll shorten the chain and try that out.

What do You all think? Thanks
WAIT--there's another option--try to find a longer screw to replace my seemingly too short B screw. I don't know whether this is a good idea to exceed the design parameters of the derail in this way????
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Old 02-13-10, 10:12 PM   #17
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My apologies in that case.

My answer was only written in response to the edited post #1. I would've said the same thing post reptilezs said without the bolded edited.
No worries, not to beat a dead horse but for clarity the OP's post was originally more like this:

My everyday beater bike is a 1994 Specialized Hardrock that's pretty much stock.

The original crankset is 28-38-48.

The original cassette is 12-28 (7-speed Shimano HG)

The original rear derailleur (still installed) is Shimano Alivio.

I recently replaced the 12-28 with 12-32 (7-speed) SRAM cassette.

Then a comment like oh I have to go now so I'll just post this half baked post and be back later...OP apparently is fond of the edit thing (and the bold thing).
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Old 02-14-10, 07:02 AM   #18
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Go ahead and shorten the chain I would start by just taking one link out not re-sizing to middle big..if that doesn't work take another link out..as long as the jockey wheels and not parallel with the ground when your in big big it will be fine you shouldn't be in big big anyway..
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Old 02-14-10, 08:44 AM   #19
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Go ahead and shorten the chain I would start by just taking one link out not re-sizing to middle big..if that doesn't work take another link out..as long as the jockey wheels and not parallel with the ground when your in big big it will be fine you shouldn't be in big big anyway..
+1. I'd possibly even go as far as to order a Half Link so I could do an in-between step. KMC makes one for 7 and 8 speed chain.
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Old 02-14-10, 11:12 AM   #20
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Thanks, Guys--

It turns out that not having an appropriate derailleur on there is really bugging me. I can get another Alivio (of proper capacity) for $29. It's kind of a mediocre performer from what I read in the reviews, however.
http://www.jensonusa.com/store/produ...erailleur.aspx

There's also this one, which looks real good since it's half price!
http://www.jensonusa.com/store/produ...erailleur.aspx

I don't have any experience with "Rapid-rise", although the concept sounds great from what I read. Any compatibility issues with my old grip shifters?

I can possibly beat these prices if I shop around. Let's forget price and, just comparing the two, there's the run-of-the-mill, plodding Alivio that I know will work ok and give middling performance for a long time. And then there's the much higher quality but unfamiliar (to me) technology of the LX with possible compatibility issues.

Which would you get?
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Old 02-14-10, 11:14 AM   #21
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I did shorten the chain

and it does work ok, but I don't like it as a long-term solution--it's like sending your child to school with one shoe or something . . .
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Old 02-14-10, 11:23 AM   #22
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Originally Posted by ClarkinHawaii View Post
Thanks, Guys--

It turns out that not having an appropriate derailleur on there is really bugging me. I can get another Alivio (of proper capacity) for $29. It's kind of a mediocre performer from what I read in the reviews, however.
http://www.jensonusa.com/store/produ...erailleur.aspx

There's also this one, which looks real good since it's half price!
http://www.jensonusa.com/store/produ...erailleur.aspx

I don't have any experience with "Rapid-rise", although the concept sounds great from what I read. Any compatibility issues with my old grip shifters?

I can possibly beat these prices if I shop around. Let's forget price and, just comparing the two, there's the run-of-the-mill, plodding Alivio that I know will work ok and give middling performance for a long time. And then there's the much higher quality but unfamiliar (to me) technology of the LX with possible compatibility issues.

Which would you get?
either derailleur will be fine. i personally do not like rapid rise. grip shifts will work with rapid rise
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Old 02-14-10, 08:45 PM   #23
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either derailleur will be fine. i personally do not like rapid rise. grip shifts will work with rapid rise
Thanks!
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Old 02-14-10, 08:49 PM   #24
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Thanks!
Don't kid yourself. The alivio is a perfectly fine derailleur. It will shift and it will **** as well as an LX when new. If I was you and I could afford an LX i'd buy that - quality stuff lasts.
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Old 02-25-10, 10:39 AM   #25
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After-action report

Ok, received the new long-cage Alivio rd from Jenson. Went on smooth and easy and now it shifts like a new bike. For others who may want to do this in the future, I offer these suggestions for your consideration:

Your old shifting cable inner wire is going to have to be fed through the hole in the new derail. This means that you have to remove the crimped-on cable end. This is not reusable, so you will have to have a new one ready to put on after the installation.

After removing the crimped-on cable end, your old wire may be frayed and not fit through the hole in the new rd--would not hurt to have a spare wire handy, just in case.

If you put on a new shifter cable wire, it will probably have to be cut to length. This is easier said than done unless you have quality cable cutters.

The bolt that attaches the rd to the bike frame is spring-fit, which means that you feel a good bit of resistance just turning the bolt in the derail, even without attaching it. So you have to hold the new rd at just the proper angle to the bike frame and be VERY careful not to strip the threads in the frame or derail hanger. This is important because I usually fiddle a bolt around until it threads easily, and determine that it is feeding into the threads properly by the lack of resistance; but you can't do that here, because you will always have that built-in resistance.

I recommend thoroughly cleaning out the bolt-hole in the frame and putting some grease on the threads (which you should anyway, to resist corrosion fusing.
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