shortening chain causes problems

[goodmojo]

I had a 3 ring setup 24/32/42 I replaced the 42 with a bash. I just replaced the rear derailleur with a GS (medium) shadow plus (had an SGS - long cage). Bike rode fine around on the street, didnt take it on the trail yet. I was reading and realized I probably needed to shorten the chain. So I shortened it, but not quite enough - I had 4 links of overlap. I simply could not get everything adjusted. Specifically the front derailleur would not shift from the big to the small ring if the rear derailleur was on the highest 4-5 gears (smallest cogs). If I rode the bike it actually shifted, but on the stand it would not.

I bit the bullet and shortened the chain by two links so there are only two links of overlap and the bike instantly shifted properly.

To sum:
chain way too long - shifted fine
Chain 4 links overlapped - could not get it setup properly
chain 2 links overlapped - worked fine

Can anyone explain what was happening here?

Also now that the chain is shorter, when I am on the largest cog and the large ring, the bottom pulley is forward of the top pulley. I seem to recall reading that the farthest it should go is straight below the top pulley. Is my setup bad? I can take a picture if necessary.

[Slash5]

Not sure about your shifting problem, doesn't make sense to me.
If you have a hardtail, I'd say your chain is still too long. In your big-big gear combination, the rear derailleur should be stretched out, not horizontal but getting that way. You need some flex but not much. Take a look on the Park site, they have info on it - or Google it, lots of advise on it.

[Bone Saw]

The proper way to get the correct chain length is to route the chain OUTSIDE of the derailleur and on the largest chain ring on the crank and the largest cog in the rear. Have the chain stretched as tight as possible and then add two links to that. When routed through the derailleur, it will definitely pull the lower pulley in front of the upper one, but still have enough slack to move properly. Your set up is OK and you might even be able to shorten the chain by another link as long as there is enough chain length so as to get around that longest chain length gearing and still have a little bit of slack so that it doesn't bind.
The only caveat to this is that on certain suspension designs, you may need to cycle the rear suspension through it's stroke to find the spot where the chain length is the longest. Let all of the air out of your rear shock and move the rear wheel through it's travel and see if you still have enough chain length all the way through.

[goodmojo]

The proper way to get the correct chain length is to route the chain OUTSIDE of the derailleur and on the largest chain ring on the crank and the largest cog in the rear. Have the chain stretched as tight as possible and then add two links to that. When routed through the derailleur, it will definitely pull the lower pulley in front of the upper one, but still have enough slack to move properly. Your set up is OK and you might even be able to shorten the chain by another link as long as there is enough chain length so as to get around that longest chain length gearing and still have a little bit of slack so that it doesn't bind.
The only caveat to this is that on certain suspension designs, you may need to cycle the rear suspension through it's stroke to find the spot where the chain length is the longest. Let all of the air out of your rear shock and move the rear wheel through it's travel and see if you still have enough chain length all the way through.

I did determine the chain length by running the chain over the two largest cog/ring and then did 2 links of overlap. When I had 4 links over overlap I could not get the bike to shift properly. When I had like 8 links of overlap it shifted fine. I did not bottom out the suspension and I guess Ill need to do that too.

thanks!

[goodmojo]

Not sure about your shifting problem, doesn't make sense to me.
If you have a hardtail, I'd say your chain is still too long. In your big-big gear combination, the rear derailleur should be stretched out, not horizontal but getting that way. You need some flex but not much. Take a look on the Park site, they have info on it - or Google it, lots of advise on it.

when I am on the big cog/big ring it looks like this (bottom pulley slightly in front):



but it seems

like I could go almost this far:



(That is too far, but close to it would be ok).

So given that I did the chain length properly, do I want to shorten it even more so that when I am on the big cog/ring combo the rear derailleur is more horizontal? Is there any advantage to shortening it or should I just leave it?

I suspect that I dont even need to test with the suspension because I have plenty of slack left in the derailleur. Is that true?

[ryguy135]

That looks to me like too short of a chain. Definitely add a link.

[goodmojo]

That looks to me like too short of a chain. Definitely add a link.

those pictures are from pink bike, the top picture looks like how mine looks on the big cog/ring

The second picture shows a more horizontal derailleur that is not setup right. My question is if it is slightly less horizontal is that ok?

[Bone Saw]

Yes to your last question. I would add one more link to the pictured chain. Somewhat horizontal is just fine, but having the derailleur totally stretched out is a bit too tight.

[goodmojo]

Yes to your last question. I would add one more link to the pictured chain. Somewhat horizontal is just fine, but having the derailleur totally stretched out is a bit too tight.

is it all right if on the big/big combo, my derailleur looks like the first picture where the bottom pulley is vertical to the top pulley or should I remove a lot of links?

[jeffscott]

is it all right if on the big/big combo, my derailleur looks like the first picture where the bottom pulley is vertical to the top pulley or should I remove a lot of links?

Ta picture of the bike with the big/big and little/little combos

They both should be working.

[kapusta]

is it all right if on the big/big combo, my derailleur looks like the first picture where the bottom pulley is vertical to the top pulley or should I remove a lot of links?

You certainly CAN remove a link. Don't know that you NEED to. Biggest thing is that the shorter the chain, the less it slaps and flops around in rough terrain, so less likely to drop the chain.

I have a 2x9 setup, and in the big/big combo, my RD is somewhere between the two positions shown in those pictures.

[goodmojo]

You certainly CAN remove a link. Don't know that you NEED to. Biggest thing is that the shorter the chain, the less it slaps and flops around in rough terrain, so less likely to drop the chain.

I have a 2x9 setup, and in the big/big combo, my RD is somewhere between the two positions shown in those pictures.

Thanks, appreciate the advice. I looked at it again tonight and it is more at a 45 degree angle, so about halfway between. Im going to leave it.