Bicycle Mechanics - Strange Problem with Connex Link

The chain bounced on the cassette (didn't engage the teeth) when the link was passing over it. Couldn't figure out why, so took to LBS. He switched the link around, saying it was on backwards. Worked fine for about 20 miles. Then it started happening again, to the point where on my ride today I switched it around again. Worked great for 15 miles, no problem, smooth as silk, and then it started again. On every pass over the cassette the link wouldn't engage. This is getting really frustrating. Any idea what could be going on here? It clearly is a function of the Connex link not engaging in the cog properly when passing over it, but why? Oh, it's a Shimano Ultegra chain and the proper link.

There ain't no forwards or backwards. How much did you pay for this servce? Whatcha got is a "stiff link", it's binding up.

There ain't no forwards or backwards. How much did you pay for this servce? Whatcha got is a "stiff link", it's binding up.
OK, but it's the second Connex I've tried (I had a spare and when this first happened the first thing I did was replace the Connex with a new one). I have these on two other bikes and they work flawlessly. I wonder if I should reconnect the chain with a regular pin and stick the Connex on another part of the chain(?)
(Oh, and he didn't charge me anything.)

You got the link upside down

I should have been clearer the top and bottom of the link are different. I can't remember what side is up but look closely at the link and put the bottom on top.

There ain't no forwards or backwards.
NOT true. Wipperman Connex fits only one way without skipping.

http://www.velimpex.com/wippermann_howto.php

http://www.velimpex.com/images/connex-link.gif

The cogs and/or chain may be worn. When's the last time you checked chain wear?

NOT true. Wipperman Connex fits only one way without skipping.

http://www.velimpex.com/wippermann_howto.php

http://www.velimpex.com/images/connex-link.gif

The cogs and/or chain may be worn. When's the last time you checked chain wear?
IMHO the first part of this statement is not always true. I have used them (CONNEX) for over 15,000 miles on a Campy Record 10 speed and the only thing that happens on MY bike is that there is a slight clicking noise if it is on upside down. Shifts just as well either way.

My experience with Connex links is the same as RockyMtnMerlin's. Agreeing with capwater, I refer you to Sheldon Brown's essay on "stiff links" in his "derailer" article (http://www.sheldonbrown.com/derailer-adjustment.html):

"If you have a regular, repeating skip or hitch every 3 or 4 turns of the pedals, you may have a stiff chain link. This is commonly the link where the chain was joined when it was installed. When the chain tool presses the pin through the chain, the head of the pin tends to pull the uppermost chain plate along with it, so that the two outer plates are squeezing together against the inner plates.

"The easiest way to fix this is to bend the problem area of the chain into a "Z" shape, with the bad joint on the diagonal part, then flex the chain back and forth. This will slightly spread the tight plates, and free up the link.

"If your chain has a link that has been bent in a chain-jamming incident, it can cause similar symptoms. Generally, the bent link (or the whole chain) will need to be replaced.

"The easiest way to spot stiff/damaged links is to shift the bike into the small/small gear (the gear you should never actually ride in.) This gear has the chain at its slackest, and flexes it farther than any other gear, as it goes around the small rear sprocket and the derailer pulleys. Slowly backpedal while watching the chain as it feeds through the rear derailer, and you will usually be able to see the bad link jump."

The cogs and/or chain may be worn. When's the last time you checked chain wear?
It's a new chain and cassette (couple hundred miles), so that can't be the problem.

"The easiest way to fix this is to bend the problem area of the chain into a "Z" shape, with the bad joint on the diagonal part, then flex the chain back and forth. This will slightly spread the tight plates, and free up the link."
I'll give this a shot, but the Connex doesn't press in like a regular chain pin so hard to imagine it's causing the kind of pressure that results in stiff links.

This is a really strange problem in that you have determined the problem is with the Connex link but it only happens after 15-20 miles of use and then when turned over works fine for another 15-20 miles then it skips again. If it wasn't for the mileage thing, I would think they may have given you the wrong link when you bought it. What could change in 15-20 miles that would all the sudden cause the skippping and then go away when the link is turned over then happen again after 15-20 miles? I think you are going to have to find a really knowlegdeable mech to look at the chain and the cassette and isolate the problem.

I'll give this a shot, but the Connex doesn't press in like a regular chain pin so hard to imagine it's causing the kind of pressure that results in stiff links.
Are you sure that you have the right size link for the chain? There are four or five Connex sizes. Do you know what your chain size and Connex sizes are?

Are you sure that you have the right size link for the chain? There are four or five Connex sizes. Do you know what your chain size and Connex sizes are?
The box says it's for Shimano 10 speed chains.

OK, the problem is definitely the fact that the link "stiffens". Question is why. I bent it back and forth slightly as suggested above, and put some grease on the link, and it seems to work OK for now. Question now is whether it will last. Seems like it works fine for a while and then stiffens up over time.

IMHO, it sounds like you may be on the edge of a misadjusted RD cable. It may be happening over time because of the flexing of the frame while riding.

Try tweaking the barrel adjuster.

IMHO, it sounds like you may be on the edge of a misadjusted RD cable. It may be happening over time because of the flexing of the frame while riding.

Try tweaking the barrel adjuster.
Thanks. Aside using sight to make sure the top RD pulley is directly underneath the cogs, any other way to check if the RD cable is properly adjusted? Also, if the frame is flexing will this help?

Thanks. Aside using sight to make sure the top RD pulley is directly underneath the cogs, any other way to check if the RD cable is properly adjusted? Also, if the frame is flexing will this help?

What I do is put my bike in my trainer, then spin through the gears while in the big chain ring to check how smoothly they change. If it seems that it takes too long to go up a cog or down a cog during any of the gear changes, I'll turn the barrel adjuster, a little bit, in the appropriate direction, then check the correction. My goal is to make the gear changes just as smooth in either direction.

What I do is put my bike in my trainer, then spin through the gears while in the big chain ring to check how smoothly they change. If it seems that it takes too long to go up a cog or down a cog during any of the gear changes, I'll turn the barrel adjuster, a little bit, in the appropriate direction, then check the correction. My goal is to make the gear changes just as smooth in either direction.
OK, thanks, I'll give that a try (though no trainer--just a bike work stand).