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Old 10-28-12, 03:56 PM   #1
lanab
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Use cogs from Dura-Ace Freewheel on Freehub?

Can i remove the sprockets on a Dura Ace 6-speed MF-7400 and put the sprockets on a Dura Ace 6-speed Hub?
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Old 10-28-12, 04:02 PM   #2
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My guess is no. But I really don't know, so wait for someone else to respond.
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Old 10-28-12, 04:02 PM   #3
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No, absolutely not. The spline diameter and pattern are completely different.

FWIW: many years ago at Euro-Asia Imports my job included customizing freewheels and cassettes for customers. I probably did hundreds:

http://www.euroasiaimports.com/produ...-1102p3429.htm
http://www.euroasiaimports.com/produ...-1140p5149.htm



I know this isn't a Dura-Ace:
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Old 10-28-12, 04:21 PM   #4
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Hi Jeff,

Thanks, could you guide me what to do with another strange problem i have, my groupset is Dura Ace EX with 6-speed Uniglide cassette.

I installed a new chain SRAM PC890 and i have huge problems figuring out why the chain won't mesh with the smallest cog when i am running it on the largest chainring, i don't know how the old chain behaved as i binned it which i regret now.

I tried everything, i have lubed the cable to the DR and checked it moves freely which it does, i have adjusted the triming screw on DR, i can make the chain mesh with smallest cog if i move the adjustment screw very far out, but then it will jump out of the sprocket under load as it's already too far out.

After reading forums they say this chain should work great with Uniglide 6-speed.

I don't have any problems when chain is on smallest chainring and moving to smallest cog at the back, only when on largest chainring.

The derailleur hanger seems straight as well.

If you can give me any advice i would be happy, this is driving me nuts right now....
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Old 10-28-12, 04:27 PM   #5
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OK, start over from the beginning, and check all of the adjustments in sequence: http://www.parktool.com/blog/repair-...nts-derailleur

"Seems straight" isn't good enough. Have the derailleur hanger checked with a proper gauge.

If the rear derailleur is old and worn, it might create shifting issues, too.

Also, a new chain on an old cog might not match due to wear on the cog. That doesn't sound like the case here (since it works OK on the small chainring), but it's hard to tell without seeing the bike in person.
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Old 10-28-12, 04:32 PM   #6
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Also it seems that the limit settings i do with the bike in stand changes when i start to ride the bike and put load on to it, could there be fatigue in the metal somewhere at DR or axle or hub?

There is some small wooble in the hub as well, but very small, maybe it's normal?
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Old 10-28-12, 05:23 PM   #7
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"could there be fatigue in the metal somewhere at DR or axle or hub?"
I'd pull the wheel and check for a bent or broken axle, it only takes a minute.
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Old 10-28-12, 08:55 PM   #8
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Also it seems that the limit settings i do with the bike in stand changes when i start to ride the bike and put load on to it, could there be fatigue in the metal somewhere at DR or axle or hub?

There is some small wooble in the hub as well, but very small, maybe it's normal?
Wobble where? Is there play in the rear wheel bearings, or do the cogs wiggle when the wheel is turning but the cogs are not? The bearings can be adjusted, while "cog wiggle" is a consequence of the construction of the hub and not an issue.

Back to your original problem: as I said, go back to the Park Tools page and recheck all of the adjustments, in proper sequence. You keep talking about adjusting the limit screw- you only need to do this once, and never touch it again. After that, you adjust the indexing with the adjusting barrel on the cable.
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Old 10-28-12, 10:46 PM   #9
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Ummmm... isn't the SRAM PC890 for seven, eight and nine-speed cassettes? Isn't it being used on a six-speed cassette, and that cassette is the Uniglide cassette with the twisted teeth design?
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Old 10-28-12, 11:16 PM   #10
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Hi Jeff,

Thanks, could you guide me what to do with another strange problem i have, my groupset is Dura Ace EX with 6-speed Uniglide cassette.

I installed a new chain SRAM PC890 and i have huge problems figuring out why the chain won't mesh with the smallest cog when i am running it on the largest chainring, i don't know how the old chain behaved as i binned it which i regret now.
I had this problem. It was related to having an old Simplex derailleur in which the parallelogram pivots were worn out. The deralleur cage was so sloppy that it would not get down to the smallest cog. Like you, this problem only showed up when in the big ring, probably because the extra tension on the chain twisted the derailleur so that it could generate the force to drop into the smallest cog at the back.

You likely have another problem related to your old Dura-Ace cassette hub. The high cog profile of these old cassettes made it more challenging for the chain to jump between cogs. Especially to the smallest cog. Plus, the old non-slant parallelogram derailleurs (such as your Dura-Ace EX) could not maintain a constant chain gap between the derailleur jockey wheel and the the small cogs. All told, the hub and the derailleur you now have was never that good at shifting, even when new. A modern derailleur, a new rear wheel with a modern cassette or freewheel, and a modern chain will be far superior to what you have now.
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Old 10-31-12, 11:18 AM   #11
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I bought a cheap new chain CN-HG40 which is 7.4mm wide just to try out and the problem is now gone in bench.

Problem is now back when riding the bike under force, i am fed up with this now as i don't know what part is faulty, for sure it's not the chain.

What could be affecting the changes when riding the bike?

Last edited by lanab; 10-31-12 at 11:49 AM.
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Old 10-31-12, 02:02 PM   #12
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Thanks, could you guide me what to do with another strange problem i have, my groupset is Dura Ace EX with 6-speed Uniglide cassette.

I installed a new chain SRAM PC890 and i have huge problems figuring out why the chain won't mesh with the smallest cog when i am running it on the largest chainring, i don't know how the old chain behaved as i binned it which i regret now.

If you can give me any advice i would be happy, this is driving me nuts right now....
The smallest cog is the one with the most wear. Also the smallest cog is the one with the fewest number of teeth gripping the chain. The wear on the old chain matches the cogs, that's why it doesn't slip when torque is applied. When a new chain is used, it will skip. That is why we always recomend customers use new cogs with new chains.

Since you can't change new cogs, just tune it so it doesn't go down to the smallest cog. Let the chain wear down till they match up. It could take a few months of riding, then adjust it down to the smallest cog.
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Old 10-31-12, 03:02 PM   #13
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Since you can't change new cogs, just tune it so it doesn't go down to the smallest cog. Let the chain wear down till they match up. It could take a few months of riding, then adjust it down to the smallest cog.
The chain doesn't skip under load, hard to explain when not riding the bike...

Yes but it works perfect on the smaller chainring, the problem is when chain is on the large chainring, the chain needs to come down at a deep angle when on large chainring and that means the limit screw being way out on rear derailleur, problem then is that the pulleys in the hanger will rattle when i paddle backwards as they are way too far out but that is the only setting that make the chain goto the smallest cog when being on the large chainring.

This is so odd as i don't know where to look anymore, i have checked the derailleur for fatigue in the pivots and the spring seems well, this is a well taken care of bike history.

But i guess i will wait and see how the chain adjust to the sprockets or i try find a new cassette or replace the smallest cog if i can find one.

Would you say it's ok to replace with Dura Ace AX sprockets instead of EX, are they smoother when shifting than EX?

Last edited by lanab; 10-31-12 at 03:05 PM.
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Old 10-31-12, 09:22 PM   #14
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Would you say it's OK to replace with Dura Ace AX sprockets instead of EX, are they smoother when shifting than EX?
As far as I can remember, Dura-Ace EX and Dura-Ace AX Uniglide cogs are identical.
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Old 10-31-12, 10:28 PM   #15
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The chain doesn't skip under load, hard to explain when not riding the bike...

Yes but it works perfect on the smaller chainring, the problem is when chain is on the large chainring, the chain needs to come down at a deep angle when on large chainring and that means the limit screw being way out on rear derailleur, problem then is that the pulleys in the hanger will rattle when i paddle backwards as they are way too far out but that is the only setting that make the chain goto the smallest cog when being on the large chainring.

This is so odd as i don't know where to look anymore, i have checked the derailleur for fatigue in the pivots and the spring seems well, this is a well taken care of bike history.

But i guess i will wait and see how the chain adjust to the sprockets or i try find a new cassette or replace the smallest cog if i can find one.

Would you say it's ok to replace with Dura Ace AX sprockets instead of EX, are they smoother when shifting than EX?
What are you using the join the chains?
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Old 11-01-12, 12:33 PM   #16
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Using SRAMs own quick link.
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Old 11-01-12, 01:45 PM   #17
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IProblem is now back when riding the bike under force
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The chain doesn't skip under load
I'm guessing the cog is worn out. Dura Ace high gear cogs are Dura Ace specific due to their smaller diameter opening. Good luck.
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Old 11-03-12, 11:45 AM   #18
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Ok i replaced the cassette with a NOS one and the problem persist, i have now checked the RD if the pivots are worn and they are to some degree, it's the DA EX RD-7200.

What do you suggest i do now? i want to keep it as original as i can and a new RD-7200 i can't find right now, could i buy the RD-7402 which is said to be for 8-speed? could i make it work for 6-speed just by adjusting the limits like my old one or will it not work?
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Old 11-03-12, 01:32 PM   #19
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As long as you don't have index shifters, you can use any rear derailleur in the Known Universe.
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Old 11-03-12, 02:43 PM   #20
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Ok i replaced the cassette with a NOS one and the problem persist, i have now checked the RD if the pivots are worn and they are to some degree, it's the DA EX RD-7200.

What do you suggest i do now? i want to keep it as original as i can and a new RD-7200 i can't find right now, could i buy the RD-7402 which is said to be for 8-speed? could i make it work for 6-speed just by adjusting the limits like my old one or will it not work?
Yes, the 7400 has a superior design than the 7200 and will shift better than the 7200 ever will. Make sure you adjust the limit screws to avoid the derailleur going up into the spokes.

The 7400 is designed to take a 26 tooth rear cog max, maybe a 28. No bigger.

Your shifting will be even better if you replace your rear hub and get rid of the Uniglide cogs.. Uniglide shifting performance is better than what came before it, but it is still slow and clunky. Hyperglide cogs shift much crisper.
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Old 11-03-12, 03:05 PM   #21
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Yes, the 7400 has a superior design than the 7200 and will shift better than the 7200 ever will. Make sure you adjust the limit screws to avoid the derailleur going up into the spokes.

The 7400 is designed to take a 26 tooth rear cog max, maybe a 28. No bigger.

Your shifting will be even better if you replace your rear hub and get rid of the Uniglide cogs.. Uniglide shifting performance is better than what came before it, but it is still slow and clunky. Hyperglide cogs shift much crisper.
The 7400 is available in several models, the 7400 for 6-speed and 7401 for 7-speed and the 7402 for 7-8 speeds right? so you are sure i can use the 7402 with my current setup or shall I buy the 7400 instead? if i buy 7402 today i could also upgrade the hub later for 8-speed HG which is good.

Just want to be sure the 7402 will work with my current setup as i don't have SIS today.

Last edited by lanab; 11-03-12 at 03:55 PM.
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Old 11-03-12, 05:16 PM   #22
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The 7400 is available in several models, the 7400 for 6-speed and 7401 for 7-speed and the 7402 for 7-8 speeds right? so you are sure i can use the 7402 with my current setup or shall I buy the 7400 instead? if i buy 7402 today i could also upgrade the hub later for 8-speed HG which is good.

Just want to be sure the 7402 will work with my current setup as i don't have SIS today.
As I said before- if you don't have SIS indexed shifters, you can use any rear derailleur.
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Old 11-05-12, 07:57 AM   #23
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Thanks.

Update to my problems!

I have now got it to work better after i disassembled the DR and removed the springs and put some new grease in, also tightened the hanger spring inside the DR a little more, at least now it actually goes to the smallest cog when riding the bike, albeit a few seconds slow better than never

Now i was thinking about the other spring in the DR which is for B-tension, how important is that to gear changes or can i let it be? this spring decides how close or far the pulley is from the cogs....
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