Derailleur pullys.

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compo

Veteran
Location
Harlow
Is the tension pulley the lower one in a derailleur cage. If so then the guide pulley can only be the top one. I have replacements and am not 100% sure which are which and the worn out ones have no markings other than Shimano. Thanks.
 

KneesUp

Guru
I've never noticed a difference between them, but then I'm not very observant.
 
OP
OP
compo

compo

Veteran
Location
Harlow
I've never noticed a difference between them, but then I'm not very observant.

I haven't either. The new pulleys are marked guide and tension. The tension pulley has shaped edges on the edges of the "teeth" and a rotation direction arrow on it.
 

sittingbull

Veteran
Location
South Liverpool
When assembled the upper pulley should have noticeably more lateral play (assuming the bushings have not been swapped between pullies).

I believe this applies to Shimano pullies (possibly others?) and is the case with several I've stripped and greased recently.
 
OP
OP
compo

compo

Veteran
Location
Harlow
Thanks for the comments. I have put the new ones on. Once I stopped and looked at them closely it was pretty obvious which went where.
 
Location
Loch side.
Some puleys are also directional. This is not because the bearings/bushes have to turn in one direction only, but due to offset in the wheel's centerline. Get the offset wrong and the tension pulley wants to climb off the rails when the chain is on the largest cassette sprocket. Your clues are arrows on the black wheel.
 
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