Different tooth patterns on Shimano 11T Jockey wheels?

[PpPete]

Older Shimano 11 speed road grousets had teeth on their tension and guide pulleys that appear of identical height.

But newer editions of the 11 speed groupsets seem to have teeth that are "taller" on the guide pulley than on the tension pulley - and the instructions are that it is important to get them the right way around.

And then on 12 speed, we are back to (apparently) identical heights for both

Anyone know what's going here?

 

[raleighnut]

It is important to get them the right way round as the guide pulley has a degree of side to side 'Float' (About 1mm) that is how Shimano got indexing to work quietly. As for the bigger teeth .....................dunno,sorry

 

[wafter]

Can't comment on the tooth profile, however comparing the top two pictured there are more differences:

The top jockey wheels come on lower-end RDs, run on solid bushes and as @raleighnut has already pointed out have an amount of lateral float; presumably to allow an amount of alignment tolerance on indexed systems.

The wheels pictured below come on higher-end RDs, run ball races and have no lateral float. Presumably there is a reduced need to accommodate lateral inconsistencies as the tolerances are better on higher-end groupsets...?

I fitted some of the ball-raced examples in place of the bushed jobs in the M592 RD on my Fuji....

 

[PpPete]

Interesting, I'd not considered the difference in the amount of lateral float...

I should perhaps include at this point the background behind the OP question.

1st: I'm running 11 speed mechanical 105 (7000 series) which has bushed jockey wheels with some lateral float, the guide pulley having the taller teeth. No particular shifting issues, but I've upped my mileage significantly, so in advance of these pulleys wearing out, I bought (from AliExpress) a pair of cheap pulleys which had bearings, and "claimed" compatibility with Shimano 11 speed systems. Turns out the two pulleys were identical and both had that shallow tooth profile of OEM tension pulleys.
Not got around to fitting them yet, so was wondering if the tooth profile would affect the shifting quality, and now you've got me thinking about how presence of, or lack of, float would affect things too.

2nd: I have a little bodged contraption of three old jockey wheels screwed to a board, and to break-in newly waxed chains I run the chain over one, under the next, and over the third. Works very well, except that the chain sometimes skips off the shallow toothed jockey wheels as I move it backwards & forwards, and when I realised that there was such a thing as taller teeth, I thought that might be an improvement.

Bottom line is that even if shifting performance is negatively affected by any experimentation with non-OEM parts, I will have another use for the cheapo stuff.

 

[raleighnut]

Can't comment on the tooth profile, however comparing the top two pictured there are more differences:

The top jockey wheels come on lower-end RDs, run on solid bushes and as @raleighnut has already pointed out have an amount of lateral float; presumably to allow an amount of alignment tolerance on indexed systems.

The wheels pictured below come on higher-end RDs, run ball races and have no lateral float. Presumably there is a reduced need to accommodate lateral inconsistencies as the tolerances are better on higher-end groupsets...?

I fitted some of the ball-raced examples in place of the bushed jobs in the M592 RD on my Fuji....

My Carlton originally had a Simplex rear mech and every now and then (after a gearchange) the chain sideplates would run on the top of the teeth leading to a 'no-drive' situation..........not nice when honking up a hill.