I’ve been attempting to do all of my own wrenching lately, and figured replacing the chain would be easy…but of course I’ve managed to f’ it up. I removed the old chain, busted out the new and measured it up to the old…lo and behold I may have shortened the new chain one link to much, as when I shift to the smallest cog the chain jumps off and into the chainstay every time. My question is, can I simply add on one of the links that I had just removed when shortening it? How do I go about doing this? Thanks!
It isn’t jumping off because of one link. Re adjust the limiting screw on the rear derailleur.
one link is no big deal
.
If you measured your new chain to the old one; if anything your new chain would be too long. Since chains tend to stretch as they wear. So I don’t think that’s the problem.
First check to see if your wheel is correctly seated within the dropouts. If it’s not aligned properly that could make the chain jump.
Did you properly thread the chain through the rear derailleur?
Did you hit the rear derailleur? Because you could have bent the hanger somehow. Generally you only have to set the limit screws on the the rear derailleur once when you first install it.
FWIW here’s a fast and quick why to size a chain. Rap the chain around the large chain ring in the front and largest cog on the cassette without threading it through the hanger. Join one open end to the other end of the chain (outer link meets inner link). Then cut the chain one complete link longer than that. That should do the trick.
Cheers!
Trevor
I forgot …
it could be just a stiff link were you joined the chain. This is due to the press the chain tool puts on the chain while pressing the pin through the chain.
Chains don’t actually stretch - what happens is the inside pins wear down causing the measurement from pin to pin to lengthen. The overall chain stays the same length.
You’re right. Thanks.
Thanks for the responses guys. Unfortunately, no luck. However, I’m now thinking its a compatibility issue. I originally had an Ultegra 9 spd chain on with an SRAM 12-23 cassette in the rear, and it shifted like butter. I picked up an SRAM PC-991 9 spd chain today from the LBS (all shimano and whipperman chains were out of stock) as well as an Ultegra 12-23 cassette, and now have the problem. Is it possible that the two won’t go together?
Just for the hell of it I threw the old (3300 miles) SRAM 12-23 cassette on with the new SRAM chain and it shifts beautifully. I’m very confused now and thinking a trip to the LBS is in my near future.
“Chains don’t actually stretch - what happens is the inside pins wear down causing the measurement from pin to pin to lengthen. The overall chain stays the same length.”
What? If the measurement from pin to pin lengthen then the overall chain will be longer.
jaretj
It sounds like the two cassettes are not installed to the same offset relative to the centerline of the wheel plane. This would cause your chain to run off the last sprocket on the cassette. Remove your chain and advance your derailleur to the position under the smallest sprocket and look at the position of the jockey pulley on the derailleur relative to the sprocket. It should be directly under the sprocket. Now pull your wheel and change to the Ultegra Cassette. Do the same thing. I am willing to bet the pulley will not align, it will be slightly outboard from the sprocket. If this is the case it is not a big deal unless the cassette is not fully seated, I will tell you how to adjust it.
With the chain still off you are going to adjust the limit screw on the rear derailleur. This is the screw that will limit how far the derailleur will go. There is a screw for the upper limit to keep you from jumping off the top onto your spokes and one to limit the bottom. As you look at the derailleur from the rear you will see two screws one above the other on the arm controlling the cage. It is the top screw that you will adjust for the smallest cog.
First use your shifter and shift to the 2nd to the smallest cog. Now turn the top screw clockwise ¼ turn at a time. After each adjustment shift to the smallest cog and check your alignment looking at it from the rear. If you have to adjust the screw more move back up one gear before turning the screw or you will be lifting the derailleur with the limit screw. This is hard to do and usually causes you to strip the screwdriver slot. Repeat this until the jockey pulley on the derailleur lines up directly under the sprocket at the lowest shift.
Now a quick tip, you don’t have to use the shift levers to shift back and forth during your test, just find the cable where it runs outside the housing and just pull on it like a bowstring to cause the derailleur to move up the cassette. Hold the tension while adjusting your screw then release it to see how far the derailleur can move outboard Remember just turn clockwise ¼ turn at a time. Continue to move the screw ¼ turn at a time until you think it lines up.
If you used the shortcut tip, use your shifter and verify the alignment after you think it is aligned. Pay attention to how far it fully advances before you release the shift lever, you may have to back off if it goes too far. This is normally a problem only at the top, but verify it nonetheless. There is potential for you to cause it to jump off while shifting, even if it lines up ”perfectly” under the sprocket after you have released the shift lever.
Before you replace your chain verify that the jockey pulley lines up with the largest sprocket as well. If it doesn’t, use the bottom screw to adjust the limit. If you are having problems at the small sprocket because of cassette alignment you may also have a problem at the top. I would suspect it barely engages or has trouble getting on the large sprocket.
If this is the case you need to relax the bottom limit screw by turning it counter-clockwise. You can use the same trick with the cable here. Shift to the 2nd largest gear and then pull and hold the cable to make it advance up. For the large cog do your screwdriver adjustments without pulling on the cable and in the 2nd to largest cog.
Verify that it aligns by pulling on the cable. This is the gear that can over shift while you have pressure on the shift lever. If you are satisfied, verify it doesn’t travel beyond the top sprocket while you are holding the pressure on the lever. The limit screw will stop your travel.
Now replace your chain and shift up and down through the gears. Use my quick tip for shifting by grabbing and releasing the cable again to verify it won’t jump off the smallest sprocket. Shift to the smallest sprocket, pull the cable, which will cause it to shift up then release it quickly. The chain shouldn’t attempt to climb outboard of the small cog. If it takes a second to settle in, you need to check the alignment again. First tighten the screw (clockwise) to make sure you are not over-traveling the center of the sprocket. Now, if it gets worse you need to go back counter-clockwise on the top screw to allow it to settle quickly into the sprocket. Remember ¼ turn at a time and make your adjustments in the second cog from the smallest.
Now do the same at the top. Shift to the 2nd largest sprocket and pull on the cable this will cause it to climb up to the largest cog. If it shows what I described above, then first tighten the **bottom **screw and try it again. If it gets worse then go counterclockwise, this will allow it to move in closer to the spokes. Always be careful here because you can jump off the large sprocket into the spokes. It not only scars them but you can jam the chain between the cassette and spokes. I am always conservative here and make sure the jockey pulley actually starts a little bit outboard of being perfectly aligned under the large cog before I start adjusting. Be sure to try holding the lever fully engaged for a few seconds while pedaling to make sure the full engagement before releasing the lever doesn’t carry you beyond the center of the cog.
I hope this helps rather than confuses you. If you have further problems you can post here and I will try to answer.
Regards