Chain Jumping, 9 speed Shimano

[Rooster1]

Would a very loose hub be enough to allow the chain to jump jump jump in the middle range?

 

[mjr]

What sort of jump? Auto shift yes, skate probably not. Loose hub should be pretty easy to test, no?

 

[Rooster1]

I know the hub is loose.

 

[mjr]

So fix it and if it still jumps, then it wasn't causing this!

 

[Rooster1]

Would a very loose hub be enough to allow the chain to jump jump jump in the middle range?

 

[mjr]

Would a very loose hub be enough to allow the chain to jump jump jump in the middle range?

WHAT DO YOU MEAN BY JUMP JUMP JUMP? (sorry for shouting, but I did ask earlier)

I think it can allow autoshifting by the middle sprockets being able to wobble back and forth enough to change which one aligns with the derailleur (which they can't when using one nearer the wheel) while the chain isn't being wrapped back as far by the derailleur (unlike in the higher gears).

 

[Rooster1]

WHAT DO YOU MEAN BY JUMP JUMP JUMP? (sorry for shouting, but I did ask earlier)

I think it can allow autoshifting by the middle sprockets being able to wobble back and forth enough to change which one aligns with the derailleur (which they can't when using one nearer the wheel) while the chain isn't being wrapped back as far by the derailleur (unlike in the higher gears).

I think I have over shortened the chain, this means the gear cable tension is fighting with the chain tension, so it goes up and down the bigger cogs, I took it out at lunch and on a steep hill I came to a grinding stop. I also have a known issue with the hub so there is play. Basically I have shagged all my bikes and I need a new one.

 

[Tim Hall]

I think I have over shortened the chain, this means the gear cable tension is fighting with the chain tension, so it goes up and down the bigger cogs, I took it out at lunch and on a steep hill I came to a grinding stop. I also have a known issue with the hub so there is play. Basically I have shagged all my bikes and I need a new one.

A new bike because your chain is too short? Really? While I applaud your bike buying-fu (N+1 rules,obvs), you could fix what you have for a few quid.

 

[Rooster1]

A new bike because your chain is too short? Really? While I applaud your bike buying-fu (N+1 rules,obvs), you could fix what you have for a few quid.

I just need to fix it, just joshing. off to the Bike Show tomorrow though! Best leave the credit card at home.

 

[Rooster1]

OK, on inspecting the bike carefully, and watching the chain turning, I noticed two jumps.
The first one was a stiff link - a bit annoying considering it is a new chain.
The second one was a quicklink I installed when I shortened it - it said it was a 9 speed but it was a tiny bit wider than the other links and made the chain jump.
I never stood a chance really.
Mostly sorted, I still have a semi stiff link but am confident it will sort itself.

 

[mjr]

The first one was a stiff link - a bit annoying considering it is a new chain.

View: https://www.youtube.com/watch?v=qDFSTi6aMxQ

 

[Rooster1]

I think a workstand would really help me sort my bike out, I currently have to flip the bike over and work on it that way. You can't really set gears up without a workstand.

 

[mjr]

I think a workstand would really help me sort my bike out, I currently have to flip the bike over and work on it that way. You can't really set gears up without a workstand.

You can, but it is easier with the bike the right way up, especially if the shifters are on the bars.