How much difference do new jockey wheels make to gear changes as mine are pretty worn?

not sure ray but ive just changed mine as they were worn away to nothing, i brought the bbb 8 speed ones for my 9spd set up and they work fine? so why is it you can buy 8 or 9?? got them fairly cheap from wiggle i think and iv replaced the lower with one and the other one ive used on lower again on other mech, wonder why they are marked as guide pulley and tension pulley, i see no difference...maybe someone can answer this

Standard Shimano caused my road bike to chatter loads, changed to Mt Zoom aluminium with ceramic bearings and much better shifting, use them on my Spearfish and KCNC aluminium on my Ala Carte.

Yetiman wrote:wonder why they are marked as guide pulley and tension pulley, i see no difference...maybe someone can answer this

I think one has more float than the other but i could be wrong.
Only ever changed jockey wheels once many years ago and to be honest i didn't notice any difference then but i didn't buy better quality ones either.

Agree with Ray, depending on top or bottom one has more lateral "float". Can't imagine fancy ones make much difference in the grand scheme but HYOH ;-)

After switching from squirt dry lube to muc-off wet ( as I thought this weekend would be a wash out) and collecting 2 days of bone dry dust(!) the Fargo (with deore 9spd) needed a thorough clean. I noticed the jockey wheels teeth were fine but there was loads of lateral play. Far worse than the 10 yr old xt mech on my Sunn. Are they supposed to move a good few mm side to side?