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-   -   Chain skipping gone weird (https://www.bikeforums.net/classic-vintage/284027-chain-skipping-gone-weird.html)

el twe 04-04-07 03:17 PM

Quite. As far as my eyes can tell, they're in great shape.

intron 04-04-07 03:21 PM

how many miles on the chain, and how many miles on the freewheel the chain was being used with?

el twe 04-04-07 03:31 PM

Chain is brand new.

repechage 04-04-07 03:44 PM


Originally Posted by el twe
Just added two more links to the chain (anymore and it'll be way too loose in the small ring), didn't get any better.

While there is parallax playing havoc with checking alignment, get the derailluer hanger checked and inspect the Nuovo Record for twist and or the parallogram is tweaked, it don't look great.

The cheap way could be to have the hanger adjusted and if you still do not see or want to bother checking it fully, replace the rear mech. with another "proven" unit. If that does the trick to fix its your NR unit, even the best can get tweaked.

el twe 04-04-07 03:47 PM

The hanger is perfectly aligned and only the cage seams tweaked, which leads me to believe that the problem is in either the cage itself or that particular spring.

cyclotoine 04-04-07 03:49 PM

I had problems with a shimano dura-ace chain mating with a suntour freewheel. I know you all are thinking "of course you did" but that was the setup I got on a bike I bought to I transferred it thinking it would be cool. It wasn't. I eventually put together a Regina Chain and Regina freewheel and no more problems though it is a little noisy.

McDave 04-04-07 03:50 PM


Originally Posted by el twe

Let me know if you'd like any more pictures.

It may just be an optical illusion, but that bottom dr cog looks bent to the right about half the width of the chain, particularly in photo #2.

cyclotoine 04-04-07 03:52 PM

I would remove both cage plates and put them on a flat surface. Then correct by hand. I have done this before and found I could get them flat to the eye which was good enough to make the drive train run smooth.

el twe 04-04-07 03:54 PM

Yeah, I'm afraid that that's the problem. Trouble is, I can't get it straight. Anyone wanna walk me through some sort of method for doing so (if there is one)?

I've used both an 8-speed Sram chain and a 7-speed Shimano IG chain with the same results.

EDIT: Thanks for the advice, cyclotoine. I'll give that a shot.

intron 04-04-07 03:55 PM

if the chain is jumping around than i would guess it could be the derailer, but if it is skipping, or sliding in the same gear i would say it is the freewheel.

maybe get someone to try and pedal the bike while holding it still in the suspect gears and see if the derailer is doing anything weird, or just skipping over on top of the cog.

el twe 04-04-07 04:19 PM

But this is the second freewheel it's done this on. And straightening the cage plates didn't help.

Snordalisk 04-04-07 05:13 PM

Could be as simple as worn out pivots in the derailleur. Shift so that the cage is more or less vertical, and give the cage a wiggle laterally at the bottom pulley. If it moves a whole lot that could be the problem.

Edit: just realized you said it stays on the same gear. I've only seen that happen from a new chain on worn out cogs. Guess that's no help, sorry.

el twe 04-04-07 05:45 PM

It does have some play, but I'm not sure how significant it is.

USAZorro 04-04-07 07:17 PM

Any chance to get a side-on picture of the derailleur position when it's in the gear that skips?

I'm thinking the problem is either chain wrap, or you're just getting derailleur/chain combinations that don't work well. Just last night I got to the chapter in the book that cudak888 recommended, and there aren't many chains that play well with Regina freewheels. Even fewer that would play well with one that isn't geared for racing.

el twe 04-04-07 07:25 PM

Interesting about the Regina freewheel. What book is that?

But I think I've actually ruled out chain/freewheel compatibility. I went ahead and cut a chain short and ran the bike single speed in both of the "trouble cogs." No skipping.

USAZorro 04-04-07 07:58 PM

Might just be the position the derailleur is in (how much chain wrap it's managing) when it's in the problem gears. Does it make a difference if you're on the large ring or the small ring?

The book is: The Complete Guide to Upgrading Your Bike - by Frank Berto

cyclotoine 04-04-07 08:03 PM

Is the chain skipping or slipping? I can imagine a problem of getting chain float where it rides up off the teeth and sort of slips over them...

el twe 04-04-07 09:03 PM

I guess you'd call it slipping. Chain wrap isn't great, but it's the best it can be without filing part of the der stop on the hanger.

cudak888 04-04-07 10:48 PM

Slipping? As in not engaging when shifted onto that cog?

or

Skipping, as in the chain jumping over the freewheel one tooth distance?


In the case of the former, modern chain sometimes gives this trouble on older cogs - Atom 5-speeds come to mind. Use some of that extra-wide TAYA 3/32nd chain (a black w/silver pin variant of the old Dura Ace UG chain) that Wal-Mart sells - should fix the problem.

In the case of the latter, I'll bet that 9 out of 10, the problem is the freewheel. You're just having a bad run of luck. Try replacing the freewheel with an NOS Shimano 600 UG/Dura-Ace UG from the late '80s - the first Shimano FWs with the Uniglide tooth pattern. Have had very good luck with new and used variants of those freewheels with new chains, they seem to have some pretty strong cogs. Reginas seem to be quite prone to pop up with extensive wear - enough to cause skipping. Same for Suntour. Not to say you can't find a Shimano with chainwear, but I've religated at least 4 or 5 Suntour freewheels and about 3 Reginas to the pegboard (for re-use of their upper cogs and FW bodies) due to worn cogs. Sometimes the wear is percevable by eye, in some cases, it isn't. Wrapping the chain over it rarely indicates a worn freewheel...unless the freewheel has already been worn considerably.

-Kurt

el twe 04-05-07 11:39 AM

The chain does not shift up or down when it skips, it just jumps over the cog and then re-engages. But it only does this when the derailleur is in use. I left the der on and just ran the bike singlespeed, leaving it mounted but unused (the chain completely bypassed it), and had no skipping on either of the problem cogs.

Hopefully I'll put a SR der on it and see if that solves the problem.

McDave 04-05-07 02:22 PM


Originally Posted by el twe
The chain does not shift up or down when it skips, it just jumps over the cog and then re-engages. But it only does this when the derailleur is in use. I left the der on and just ran the bike singlespeed, leaving it mounted but unused (the chain completely bypassed it), and had no skipping on either of the problem cogs.

Hopefully I'll put a SR der on it and see if that solves the problem.

I think before you put the new dr on it I should ride the bike for several miles in each of the offending cogs (while they're not skipping) to give the gears and chain a chance to mesh and break-in to each other. I've seen several posts like this where the problem goes away after a short while.

Then when you mount the new dr make sure you don't have too many links in the chain (don't think I've seen that possibility mentioned). Good luck!

el twe 04-05-07 02:31 PM

Chain length is fine. Thanks for the suggestion, I've been looking for something to do today, and that's the perfect thing.

EDIT: Except the chain on right now (for SS) isn't the one I'll use with gears, and that Sram chain is a ***** with stiff links.


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