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I can only use the highest 5 gears on my 8spd rear cog

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bianchi29er Offline
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Post: #1
I can only use the highest 5 gears on my 8spd rear cog
hi guys, i have an early 90's bianchi 29er, that used to have a rusty busted old derailleur. i removed the front derailleur and extra chainring and shifter, and recently replaced the RD with a brand new shimano deore LX, new 8 spd cassette, and new chain. i also replaced the mtn drops with a pair of flat bars that came with my husband's jake the snake. the flat bars already had shimano STX RC shifters on them, of which i kept the right(rear) one.
all that said, i know how to adjust H/L screws and cable tension, but i can't for the life of me get the shift right. no matter what i do, i can't get the chain to run up past the 5th gear, rendering the lowest 3 gears unreachable. i've read sheldon brown's guide and there is nothing in there that i haven't already done. i'm getting really frustrated, and i need to ride my bike to work tomorrow. please help!
Aug 5, 2013 04:59 PM
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nfmisso Offline
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San Jose, CA
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Post: #2
RE: I can only use the highest 5 gears on my 8spd rear cog
Questions:

Did you confirm that the RD will move the full stroke with the cable not connected?

And when the cable is not connected to the RD, that the shifter pulls it as you downshift?

If those two check out; I am at a loss too.....

Nigel
Aug 5, 2013 05:14 PM
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bianchi29er Offline
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Post: #3
RE: I can only use the highest 5 gears on my 8spd rear cog
It will move the full width unconnected. I was able to get it working once, and then it quit going all the way up to the larger rings. The shifter quits at 5, and won't click anymore. It's one of the ones with the little window that says which gear, and that is also stopping at 5. It just absolutely won't go any farther. I wondered if it was a shifter/derailleur compatibility issue?
Aug 5, 2013 05:18 PM
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painkiller Offline
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Peoria, IL. USA
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Post: #4
RE: I can only use the highest 5 gears on my 8spd rear cog
is your bike in the project series of models? post some pics of what you have. you cannot even run the gears by moving the derailluer by hand with the cable detached? so in other words you cannot set the "low limit screw" either? What is the model number of your new Lx derailluer? you may not have had your shifter clicked down before you attached the cable therefore only clicking the remaining gears. ( to many beers may cause this). check these two things freehand and you may solve this.


There are two kinds of people in the world, "Those who help themselves to people, and those who help people!"
Aug 5, 2013 05:37 PM
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bianchi29er Offline
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Post: #5
RE: I can only use the highest 5 gears on my 8spd rear cog
(Aug 5, 2013 05:37 PM)painkiller Wrote:  is your bike in the project series of models? post some pics of what you have. you cannot even run the gears by moving the derailluer by hand with the cable detached? so in other words you cannot set the "low limit screw" either? What is the model number of your new Lx derailluer? you may not have had your shifter clicked down before you attached the cable therefore only clicking the remaining gears. ( to many beers may cause this). check these two things freehand and you may solve this.

it is! i believe it is a project 5. super cool fun ride, at least until i tried to put new shiny parts on it. i followed the park tool guide to adjust, and everything went to hell(not their fault, i'm sure. it's a well written guide). the derailleur is not at fault. i don't know the model number. are there bad batches or something? it does move without the cable attached to both extremes of the cassette.
i'll try both of your suggestions first thing in the morning; your beer warning has me scared.
Aug 5, 2013 09:17 PM
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mysteriousem Offline
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Post: #6
RE: I can only use the highest 5 gears on my 8spd rear cog
I am having almost this exact same problem. Sad With a Shimano Deore derailleur, too.

I have a Trek Navigator, and after a few years of hard riding, the derailleur and shifter had pretty much worn out. I wasn't too concerned about it... I knew it would happen eventually, so I was all prepared to replace the cheap components it came with.

Unfortunately, it now shifts /worse/ with my brand new Deore derailleur than it did before!

The shifter, derailleur, and cables and housing have all been replaced with brand new shiny stuff. I've very carefully checked the housing and cable routing to make sure that I didn't make a mistake. I can shift "manually" by pushing the derailleur. I can change /which/ four gears I can get by manually pushing in the derailleur and tightening the cable there... But I can't for the life of me get the index shifter to shift outside of a four gear range! Sad

Upon inspection, it /appears/ that when I click a single gear change on the shifter, the derailleur only moves about half a gear. So if I click another gear up, it goes ahead and shifts (resulting in me getting about half my available gears, which in this case is 3 or 4, depending upon how much I've fiddled with it).

It's a very frustrating situation, since this was supposed to be a splurge to make my commute more pleasurable, and now it's actually worse than the sloppy worn out derailleur and shifter were. :/ Even more frustrating that my LBS is just as stumped as I am...

Anyway, if anyone figures out the solution to this problem, I would be super happy. Tongue

EDIT: I thought I should note that I had the same symptoms whether I was using the old grip shift or the new new "trigger" shifter, so I don't think the problem is the shifter...
Aug 6, 2013 07:53 PM
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nfmisso Offline
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San Jose, CA
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Post: #7
RE: I can only use the highest 5 gears on my 8spd rear cog
Are either of you near San Jose? I would be happy to take a look.

Nigel
Aug 6, 2013 08:17 PM
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mysteriousem Offline
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RE: I can only use the highest 5 gears on my 8spd rear cog
I am not, alas. I'm in Lubbock, Tx. Tongue
Aug 6, 2013 08:40 PM
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1FJEF Offline
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Post: #9
RE: I can only use the highest 5 gears on my 8spd rear cog
(Aug 6, 2013 07:53 PM)mysteriousem Wrote:  I am having almost this exact same problem. Sad With a Shimano Deore derailleur, too.
I have a Trek Navigator,
I can shift "manually" by pushing the derailleur. I can change /which/ four gears I can get by manually pushing in the derailleur and tightening the cable there... But I can't for the life of me get the index shifter to shift outside of a four gear range!
My Trek Navigator came with a SRAM Rear derailleur & shifter, with a 1:1 actuation ratio. which is not compatible with Shimano. It sounds like your new Shimano Deore Rear Derailleur is being operated by SRAM shifters. SRAM shifters move the cable half as much! You can get special SRAM Shimano compatible shifters, the twist shifts are MRX models.
For example, this WON'T WORK. Neither will this.
Try a new SHIMANO brand shifter, with the appropriate number of speeds and you should be good.
Aug 7, 2013 09:53 PM
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mysteriousem Offline
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Post: #10
RE: I can only use the highest 5 gears on my 8spd rear cog
(Aug 7, 2013 09:53 PM)1FJEF Wrote:  
(Aug 6, 2013 07:53 PM)mysteriousem Wrote:  I am having almost this exact same problem. Sad With a Shimano Deore derailleur, too.
I have a Trek Navigator,
I can shift "manually" by pushing the derailleur. I can change /which/ four gears I can get by manually pushing in the derailleur and tightening the cable there... But I can't for the life of me get the index shifter to shift outside of a four gear range!
My Trek Navigator came with a SRAM Rear derailleur & shifter, with a 1:1 actuation ratio. which is not compatible with Shimano. It sounds like your new Shimano Deore Rear Derailleur is being operated by SRAM shifters. SRAM shifters move the cable half as much! You can get special SRAM Shimano compatible shifters, the twist shifts are MRX models.
For example, this WON'T WORK. Neither will this.
Try a new SHIMANO brand shifter, with the appropriate number of speeds and you should be good.

Actually, I have a brand new Shimano shifter, and the problem is worse than it was with my old grip shift.

That being said, my original derailleur was a Shimano Tourney, and the shifter was an SRAM (which /really/ confused me since it always worked fine, until I looked up online and found out this type of shifter is actually made to be compatible with Shimano).

Could there be a compatibility issue with my cassette? I don't see how. From everything I'm reading online, if the Tourney worked with it, the Deore /should/ work... The cassette is not really at the end of its life, so I'd prefer not to replace it, if I don't have to.

Could I have misrouted a cable? It's not hanging on anything. I've double and triple checked and there is no extra friction happening in the cable... But I don't see how I could have misrouted, since there doesn't seem to be any other routing option!

Still completely stumped here. Sad

EDIT: This seems unlikely, given the symptoms I'm seeing, but could it be because the Deore is a 9-speed derailleur? The stuff I read online seemed to suggest that it should work fine with my 7 speeds... But I'm willing to entertain the idea that my research was wrong, if anyone knows anything more about it. Tongue
Aug 7, 2013 11:41 PM
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1FJEF Offline
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Post: #11
RE: I can only use the highest 5 gears on my 8spd rear cog
Somethings not right.
You wrote:
"I can shift "manually" by pushing the derailleur. I can change /which/ four gears I can get by manually pushing in the derailleur and tightening the cable there... But I can't for the life of me get the index shifter to shift outside of a four gear range!"
WILL THE RD will move all the way from 1st (the biggest) to 7th (the smallest) gear when moved by hand. If so it is not the limit screws on the RD.
You say that two different shimano 7 speed shifters will not move the RD across from 7th to 1st. So it is not the shifters.
Aug 8, 2013 06:28 PM
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mysteriousem Offline
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RE: I can only use the highest 5 gears on my 8spd rear cog
(Aug 8, 2013 06:28 PM)1FJEF Wrote:  Somethings not right.
You say the RD will move all the way from 1st (the biggest) to 7th (the smallest) gear when moved by hand. So it is not the limit screws on the RD.
You say that two different shimano 7 speed shifters will not move the RD across from 7th to 1st. So it is not the shifters.

I think I figured it out. The person who informed me that a 9-speed derailleur could be used on a 7-speed cassette was talking out of their butt. The 9-speed and 7-speeds have different spacing.

So I guess I'm stuck with it as-is until the next time I have money to upgrade parts. Tongue
Aug 8, 2013 06:31 PM
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1FJEF Offline
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Post: #13
RE: I can only use the highest 5 gears on my 8spd rear cog
You are not stuck yet. Please confirm that THE RD will move all the way from 1st (the biggest) to 7th (the smallest) gear when moved by hand, not just across the four cogs.
A 9speed RD wouildn't act the way yours is. If anything, it would have a wider range of movement.
Dude, I think you need to adjust the two side by side little philips screws on the RD. One limits how far out the RD can go, the other, how far in. It stops the RD from sending the chain into the spokes or onto the frame. Most new RD will have a little "L" & "H" by the screws.
Aug 8, 2013 06:36 PM
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mysteriousem Offline
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RE: I can only use the highest 5 gears on my 8spd rear cog
(Aug 8, 2013 06:36 PM)1FJEF Wrote:  Please confirm that THE RD will move all the way from 1st (the biggest) to 7th (the smallest) gear when moved by hand, not just across the four cogs.

As mentioned, I /can/ move all the way from the 1st to the 7th gear when moved by hand. The problem is clearly in the indexing.

I'm now 99.9% sure that this is a compatibility issue between the RD and the cassette. Guess that's what I get for trusting the 'experts'. Tongue
Aug 8, 2013 06:42 PM
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1FJEF Offline
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Post: #15
RE: I can only use the highest 5 gears on my 8spd rear cog
Let me check with a guy who's done it.
Aug 8, 2013 06:44 PM
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mysteriousem Offline
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RE: I can only use the highest 5 gears on my 8spd rear cog
(Aug 8, 2013 06:44 PM)1FJEF Wrote:  Let me check with a guy who's done it.

Okay. I would be more comfortable before messing with it if I was 100% confident this is the real problem.

I think the thing is that the person I asked knew that a 9-speed could also be used on an 8-speed, so they assumed it would also be fine on a 7-speed. In reality, there's just too big of a difference between the 9-speed and 7-speed spacing. (I stumbled on this info today on Sheldon Brown's website, btw... Can't believe I didn't see it there before! Guess I was focusing too much on derailleurs and trusting my knowledgeable friend and LBS to steer me right.)
Aug 8, 2013 06:48 PM
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mysteriousem Offline
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Post: #17
RE: I can only use the highest 5 gears on my 8spd rear cog
Well, darn. I think I was reading it wrong... Which means I'm back to having no clue why it's misbehaving. With a 7-speed Shimano cassette and a 7-speed Shimano shifter, it /should/ work perfectly. It just...doesn't...

Blah.
Aug 8, 2013 07:18 PM
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painkiller Offline
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Peoria, IL. USA
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Post: #18
RE: I can only use the highest 5 gears on my 8spd rear cog
I would think if you made sure your shifter was relaxed before connecting the cable, (pulling the cable by hand and clicking the shifter as if it were in the smallest cog ) and then attaching the cable. it would run the full spread. I am not saying it will shift good simply because of the way you may have your limit screws set and barrel adjusters turned and things like that. there may be a difference in chain width that would affect things. your chain may be to wide for the 9 speed derailluer. dunno what you have. Who is doing the work ?you or the shop that is stumped. did you make the call on the derailluer or the shop?. I have never used a mega9 on a 7 speed. I have used 8 speeds on 7 and six speeds on 7 before. but none the less. yours should still run the gamut. I think you are not setting the shifter properly before attaching the cable. I would think if anything it would be a problem having enough screw to set the high low limits.. I sold the last 9 speed a couple months ago so I cannot confirm pulley or chain width. but there are tech doc specs that are out there. some claim a chain is a chain but I would more say, 5,6,7,8,...9,10 speed chains. bottom line is wrong derailluer for the job, but it should still run the cogset if your shifter is not broken. But at this point I think there is a communication breakdown some where. If you have a video camera. start over and video your self and explain what you are doing each step and maybe we can watch and tip you off where you are going wrong


There are two kinds of people in the world, "Those who help themselves to people, and those who help people!"
Aug 8, 2013 08:03 PM
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nfmisso Offline
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Post: #19
RE: I can only use the highest 5 gears on my 8spd rear cog
(Aug 8, 2013 08:03 PM)painkiller Wrote:  ....... some claim a chain is a chain but I would more say, 5,6,7,8,...9,10 speed chains......

The chain MUST match the derailleur - if 9 speed derailleur for example, the chain must be 9 speed or higher - at least for Shimano. The chain must also be similar match for the cassette/freewheel. For example; 7 speed cassette with a 9 speed derailleur needs a 9 speed or higher chain. 2nd example - 7 speed cassette with an 8 speed RD - chain must be 8 speed or higher. At least for Shimano.

The indexing is in the shifter, not in the derailleur.

Now, please share the video as PK requested.

Nigel
Aug 8, 2013 08:37 PM
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1FJEF Offline
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RE: I can only use the highest 5 gears on my 8spd rear cog
(Aug 8, 2013 08:37 PM)nfmisso Wrote:  The chain MUST match the derailleur - if 9 speed derailleur for example, the chain must be 9 speed or higher - at least for Shimano. The chain must also be similar match for the cassette/freewheel. For example; 7 speed cassette with a 9 speed derailleur needs a 9 speed or higher chain. 2nd example - 7 speed cassette with an 8 speed RD - chain must be 8 speed or higher. At least for Shimano.

The indexing is in the shifter, not in the derailleur.
That is a good explanation. Also:
I didn't know that a 9 speed chain (1/2" x 11/128") would work on a 7 speed cassette!
I didn't know that there was a difference between 7 & 8 speed chains.
That may explain why my old Specialized Expedition Elite (7spd cassette) bike is so "growly" with the original Acera RD & KMC x8.99 chain (7.3mm). KMC shows that 8 & 7 speed chains (7.3 & 7.1mm pin length) are interchangeable, but perhaps they are not allowing for the RD being particular.
Aug 9, 2013 01:01 AM
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