Originally Posted by
fietsbob
My thought . because of the molded single piece, flanges & toothed pulley design, the chain oil dirt combined solids, packed in, have no place to go..
Wondering if a few holes thru the flanges .. a part of some of the CNC after market pulleys . gives some of that inevitable accumulation a way to sluff off and out..
3 speed , its no issue , backing disc gets a bit grimy , but it does not rotate in unison with the lower pulley
The side holes are there but indeed the flanges and plastic, rather than metal, likely contribute to the grime accumulation. When I looked at the aftermarket of pulleys and tensioners for Brompton, it seemed that you needed to pay a lot of money for a dubious gain. However, I may have another look.