so i may have made a mistake. so can get the chain to the correct cogs with a derailleur that you have to reach down between your legs to shift. but you have to use your right to shift two seperate systems. you can not simitaneously double shift like you can with handlebar end derailleur controld,to do this. the shifting will be slow & that why i said half step will not work with this. in 1970 i had a campagnolo record front with a 36-47-52 teeth rings. there was no derailleur that would shift well over a crossover triple until the simplex slj 523 front derailleur can out in 1979. in boston that cost $20-$30, which was a fair price. i recently saw it on a internet site for $115, which is pricey. i have 2 or 3 of these derailleurs because when these came no one was really sure what were for & i am glad that i picked a few. a road front derailleur is what you want to use for half step plus granny. i may have to reshape the cage on my simplexes, i plan to use them on my 44-57-67 crankset on my tricycle.people stated they big chainrings i bought these from highpath engineerimg in wales. the 67 was about $165. a 68 tooth ring to 110 ( the maximum) is $500 (egad!). they do nice work.