New chain being throw of Jockey Wheel

[jase_31]

HI,

Ive replaced the chain on my Subway 1. The new chain (shimano) is being throw off the bottom jockey wheel, and runs off the wheel. I cant see that anything is bent, and have cleaned the wheel and bushing. The new chain runs OK on the cassette and front chainring.

When I put the old chain (KMC) back on then it runs fine on the Jockey? Anyone seen this before? Jockeys dont seem to wear out (usually) and I cant see anything worn on the Jockey to cause a problem, or anything bent (which also seems to be discounted as it runs back on the old chain)

 

[raleighnut]

HI,

Ive replaced the chain on my Subway 1. The new chain (shimano) is being throw off the bottom jockey wheel, and runs off the wheel. I cant see that anything is bent, and have cleaned the wheel and bushing. The new chain runs OK on the cassette and front chainring.

When I put the old chain (KMC) back on then it runs fine on the Jockey? Anyone seen this before? Jockeys dont seem to wear out (usually) and I cant see anything worn on the Jockey to cause a problem, or anything bent (which also seems to be discounted as it runs back on the old chain)

Are the chains the same length ?

 

[fossyant]

Also check routing of the chain through the rear mech cage. A couple of photos and one from the rear of the bike of the rear mech at axel level.

 

[I like Skol]

Got to be chain length?

 

[Ajax Bay]

Picture from the side in small/small, please.

 

[Deleted member 26715]

Are the chains the same length ?

Got to be chain length?

Can you explain the significance of this please?

 

[jase_31]

Are the chains the same length ?

Should be same number of links, although the old chain is a bit longer as it is stretched. I have tried the new chain with an extra link in, which didnt help.

 

[raleighnut]

Should be same number of links, although the old chain is a bit longer as it is stretched. I have tried the new chain with an extra link in, which didnt help.

A shorter chain may be needed as long as Large-Large is OK

Picture from the side in small/small, please.

Likewise in Large/large.

 

[raleighnut]

Can you explain the significance of this please?

If the chain is too long the mech won't be able to maintain sufficient tension leading to it bouncing off the bottom pulley when at extreme (Cross Chained) angles

 

[Darius_Jedburgh]

Can you explain the significance of this please?

Is that a serious question?

 

[Deleted member 26715]

Is that a serious question?

Yes, is this a serious answer as it wasn't very helpful?

 

[jase_31]

Got to be chain length?

If I go back and calculate (https://www.bergfreunde.eu/chain-length-calculator/) it suggests a chain length of 110 links (139cm), so doesnt seem to be chain length. Should this be compensated by the gear in any case, depending on the gear ratio.

Runs fine with smooth changing now I am back on the old chain.

 

[Deleted member 26715]

If the chain is too long the mech won't be able to maintain sufficient tension leading to it bouncing off the bottom pulley when at extreme (Cross Chained) angles

Agreed but this is not going to happen on an extra 1 or 2 links is it?

 

[raleighnut]

Agreed but this is not going to happen on an extra 1 or 2 links is it?

Well summats causing it,

If I go back and calculate (https://www.bergfreunde.eu/chain-length-calculator/) it suggests a chain length of 110 links (139cm), so doesnt seem to be chain length. Should this be compensated by the gear in any case, depending on the gear ratio.

Runs fine with smooth changing now I am back on the old chain.

I wouldn't use a calculator, wrap big/big not through the mech and add a pair of links is my method.

There isn't a tight/stiff link in the new chain is there?

 

[raleighnut]

View: https://youtu.be/OBv97hqqd0o